Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Global Heat Uptake by Inland Waters
    Vanderkelen, I. ; Lipzig, N.P.M. van; Lawrence, D.M. ; Droppers, B. ; Golub, M. ; Gosling, S.N. ; Janssen, A.B.G. ; Marcé, R. ; Müller Schmied, H. ; Perroud, M. ; Pierson, D. ; Pokhrel, Y. ; Satoh, Y. ; Schewe, J. ; Seneviratne, S.I. ; Stepanenko, V.M. ; Tan, Z. ; Woolway, R.I. ; Thiery, W. - \ 2020
    Geophysical Research Letters 47 (2020)12. - ISSN 0094-8276
    heat uptake - inland waters - lakes - reservoirs - rivers

    Heat uptake is a key variable for understanding the Earth system response to greenhouse gas forcing. Despite the importance of this heat budget, heat uptake by inland waters has so far not been quantified. Here we use a unique combination of global-scale lake models, global hydrological models and Earth system models to quantify global heat uptake by natural lakes, reservoirs, and rivers. The total net heat uptake by inland waters amounts to 2.6 ± 3.2 ×1020 J over the period 1900–2020, corresponding to 3.6% of the energy stored on land. The overall uptake is dominated by natural lakes (111.7%), followed by reservoir warming (2.3%). Rivers contribute negatively (-14%) due to a decreasing water volume. The thermal energy of water stored in artificial reservoirs exceeds inland water heat uptake by a factor ∼10.4. This first quantification underlines that the heat uptake by inland waters is relatively small, but non-negligible.

    Resilience of River Deltas in the Anthropocene
    Hoitink, A.J.F. ; Nittrouer, J.A. ; Passalacqua, P. ; Shaw, J.B. ; Langendoen, E.J. ; Huismans, Y. ; Maren, D.S. van - \ 2020
    Journal of Geophysical Research: Earth Surface 125 (2020)3. - ISSN 2169-9003
    deltas - morphodynamics - resilience - rivers - sea level rise - sediment transport

    At a global scale, delta morphologies are subject to rapid change as a result of direct and indirect effects of human activity. This jeopardizes the ecosystem services of deltas, including protection against flood hazards, facilitation of navigation, and biodiversity. Direct manifestations of delta morphological instability include river bank failure, which may lead to avulsion, persistent channel incision or aggregation, and a change of the sedimentary regime to hyperturbid conditions. Notwithstanding the in-depth knowledge developed over the past decades about those topics, existing understanding is fragmented, and the predictive capacity of morphodynamic models is limited. The advancement of potential resilience analysis tools may proceed from improved models, continuous observations, and the application of novel analysis techniques. Progress will benefit from synergy between approaches. Empirical and numerical models are built using field observations, and, in turn, model simulations can inform observationists about where to measure. Information theory offers a systematic approach to test the realism of alternative model concepts. Once the key mechanism responsible for a morphodynamic instability phenomenon is understood, concepts from dynamic system theory can be employed to develop early warning indicators. In the development of reliable tools to design resilient deltas, one of the first challenges is to close the sediment balance at multiple scales, such that morphodynamic model predictions match with fully independent measurements. Such a high ambition level is rarely adopted and is urgently needed to address the ongoing global changes causing sea level rise and reduced sediment input by reservoir building.

    Bringing in the floods : a comparative study on controlled flooding in the Dutch, Bangladesh and Vietnamese deltas
    Staveren, Martijn F. van - \ 2017
    Wageningen University. Promotor(en): J.P.M. Tatenhove, co-promotor(en): J.F. Warner; P. Wester. - Wageningen : Wageningen University - ISBN 9789463437035 - 174
    water management - flooding - deltas - hydraulic engineering - rivers - environmental management - environmental policy - environmental control - netherlands - vietnam - bangladesh - waterbeheer - inundatie - delta's - waterbouwkunde - rivieren - milieubeheer - milieubeleid - milieubeheersing - nederland - vietnam - bangladesh

    This thesis investigates contested initiatives to restore controlled flooding in the deltas of the Dutch, Bangladesh and Vietnamese (Mekong) deltas. Restoring controlled flooding is a seemingly contradictory measure in densely populated delta areas, where approaches based on full flood prevention has been typically dominant for decades. This has instigated the question how the emergence of restored controlled flooding initiatives can be explained. Related, this study reflects on how controlled flooding could contribute to long-term flood risk management and sustainable development in deltas, which are simultaneously attractive and vulnerable places for humans to live in. In order to answer this question, a case study approach has been used to investigate social, environmental and technological factors that have shaped controlled flooding initiatives. Cases have been identified that materialized under different conditions: from very dynamic delta environments to relatively stable ones, and from interventions driven by “top-down” policies to “bottom-up” action to modify or remove embankments. This thesis has an article-based structure, which means that individual chapters (2-5) have been designed for publication with peer reviewed academic journals. Chapter 1 provides the general background information, problem definition, and objectives. Chapter 6 ties together the findings of the individual case study chapters and presents the conclusions.

    Chapter 2 conceptualizes deltas as interacting social-ecological-technological systems. It argues that a better understanding of how hydraulic infrastructure influences social processes and environmental dynamics in deltas is critical to understand how deltas evolve over time. By means of the delta trajectories concept, the chapter presents a way to understand this interaction. It also presents a way to understand the sustainability of a delta trajectory, and discusses how new flood management concepts might contribute to “realigning” the development trajectory towards more sustainable system states.

    In Chapter 3, the first controlled flooding case is investigated. The Noordwaard is an agricultural polder, located at the junction of tides and riverine discharge in the Netherlands. As part of the Room for the River programme, the northern embankments were lowered which enables the inflow of water during high water levels in the river Merwede. This reduces peak water levels in the river, supports the adjacent freshwater Biesbosch wetland by means of restored water dynamics, but also affects the possibilities for agricultural production. The chapter highlights that a strong coupling can be observed between the domains of water safety and nature development objectives, and that a top-down decision concluded a long stakeholder negotiation processes. From the perspective of “subsiding polder lands,” controlled flooding is not regarded for its strategic importance, as excessive sedimentation would hamper the intended design discharge of the area.

    Chapter 4 explores the Tidal River Management concept. In the coastal zone of Bangladesh, community-enforced embankment breaches have opened up some of the polders or low-lying areas called “beels,” and exposed them to tidal influence again. Besides stimulating agricultural production and providing safer places to live in, the extensive network of polder embankments also caused increased sedimentation in the region’s rivers, and water logging in enclosed areas due to insufficient drainage possibilities. The chapter highlights that policy debates in Bangladesh have revolved around adopting “open” or “closed” approaches, where TRM represents a hybrid form. The case showed that TRM involves water management and sediment management, and that it represented a “social opening up” for local communities and NGOs to get involved with water projects and embankment removal.

    Plans to restore seasonal flooding in the Mekong delta are center stage in Chapter 5. The Mekong delta system is very dynamic and dealing with the delta’s water resources, in connection with intensive rice production, have been heavily debated by Vietnamese and international policy makers. This chapter investigates a number of older and more recent long-term development plans for the Mekong delta. This analysis highlights how ideas about controlled flooding and flood control have gradually evolved over time. The most recent delta management plan suggests to restore seasonal flooding in some parts of the delta, as a way to safeguard downstream urban areas from peak flows, and as a way to improve the conditions for agricultural production.

    Chapter 6 summarizes the findings of the case study chapters one by one, and concisely answers the research questions. It highlights key similarities and differences when it comes to social, environmental and technological dimensions, and discusses these findings with the literature on flood risk management policy, complex adaptive systems research, and delta studies. The findings demonstrate that environmental dynamics have been critical to emphasize the potential of restoring controlled flooding, but that social and technological factors have been important enablers or constrainers for controlled flooding initiatives to take shape. In itself, controlled flooding reconciles ecosystem-based ideas about flood management with more mainstream policies based on flood control. For this reason controlled flooding can be seen as a “niche-development” with limited influence on how flood management policies, and environmental delta systems, evolve. At the same time, controlled flooding has been acknowledged for its strategic opportunities, for example when it comes to diverting peak water discharges, land heightening by means of capturing suspended sediment, and by providing nutrient for agricultural. This offers opportunities for further thinking about and conceptual development of controlled flooding.

    Quantifying the impact of socioeconomic development and climate change on Escherichia coli concentrations in the Pakistani Kabul River
    Iqbal, Shahid - \ 2017
    Wageningen University. Promotor(en): Rik Leemans, co-promotor(en): Nynke Hofstra. - Wageningen : Wageningen University - ISBN 9789463434478 - 183
    escherichia coli - rivers - climatic change - socioeconomics - water quality - regression analysis - water pollution - health - escherichia coli - rivieren - klimaatverandering - sociale economie - waterkwaliteit - regressieanalyse - waterverontreiniging - gezondheid

    Clean water is indispensable for the sustenance of life and maintenance of health. However, water quality is threatened by changes in socio-economic developments (population growth, urbanisation, livestock increase and sanitation) and climate (surface air temperature and precipitation patterns). Major water quality contaminants include microorganisms, such as fecal coliforms, Escherichia Coli (E.coli) and pathogens. Microbial contamination poses serious health risks in developing countries like Pakistan, where people do not have access to clean water due to lack of waste water treatment and thorough manure management. Therefore, to reduce the present and future health risk, it is important to understand the impacts of socio-economic development and climate-change on microbial fate and transport in surface water resources in the Kabul River Basin in Pakistan.

    The objective of this study is quantifying the impact of socio-economic development and climate change on E.coli concentrations in the Pakistani Kabul River. To reach the objective, I sampled E.coli concentrations at several locations in Kabul River, applied statistical and process based modelling, developed future global change scenarios and analysed the impact of these scenarios on E.coli concentrations. I focus on E.coli rather than pathogens, because sampling of pathogens and its chemical analysis are expensive. Kabul River Basin is a tributary of the Indus river and is located in the Hindukush-Karakoram-Himalayas (HKH) and suffers from floods every year. The population suffers from a high risk of waterborne diseases. The water is contaminated by direct sewage inputs from large cities, like Peshawar, direct manure inputs from animal sheds along the river and indirect manure inputs from the land.

    Kabul River Basin is subjected to hazardous levels of microbiological pollution. The concentration of micro-organisms is influenced by hydro-climatic variables, such as water and surface air temperature, precipitation and discharge. However, the net effect of these variables remains thus far unclear. High concentrations of E.coli were found in the main stream and its tributaries (Chapter 2). Samples were collected along the Kabul river and drinking water samples from the city of Nowshera (April 2013 to July 2015) and all surface water samples violate the bathing water criteria and all drinking water samples violate the drinking water criteria. The correlation between hydro-climatic variables and E.coli concentration was analysed. Water temperature and surface air temperature were positively correlated, most likely because high temperatures coincide with high precipitation and discharge. Precipitation and river discharge data were also positively correlated with E.coli concentrations. This shows that precipitation, which increases the surface runoff, transports E.coli and other waterborne pathogens to the river nearby (correlation with precipitation) and further upstream (correlation with discharge). A regression model was also applied that explained 61% of the E.coli variability in surface water and 55% of E.coli variability in drinking water resources, even when other factors, such as location and land-use variables are ignored (Chapter 2).

    To better understand the hydrology in the basin, the current and future flows of Kabul river were modelled using the Soil and Water Assessment Tool (SWAT), which serves as a basis for the process-based E.coli model. Flash floods occur every year in the basin as a result of increased discharge due to snow and glacier melt together with monsoon precipitation. The Kabul River Basin is one of the most vulnerable regional basin to climate change. The hydrological model was calibrated and validated for the full Kabul River Basin and performed well (NSE equals 0.77 and 0.72 respectively). Flood frequency and expected return period were analysed for a contemporary period (1981-2000) and two future periods (i.e. 2031-2050 and 2081-2100) using the Representative Concentration Pathway (RCP) 4.5 and RCP8.5 scenarios based on four bias-corrected downscaled climate models (Chapter 3). The flood frequency analysis shows that the present day’s one-in-a-fifty year event could occur between once in every 3 year (EC-EARTH and MIROC climate-models) and once in every 24 years (IPSL climate-model). This study presents climate-change impact assessment in the Kabul River Basin. The selected approach is in general well accepted in the scientific community and the results can be useful in flood management in the region. Outcomes of this study can be helpful for regions that have similar hydro-climatological conditions.

    To better understand the fate and transport of bacteria from land to water resources and to assess source contribution, the SWAT model was calibrated and validated for E.coli. Our study is the first bacterial modelling study for the Kabul River Basin (Chapter 4). The simulated concentrations have slightly lower variability than the observed concentrations. The model performance could be improved further by using more input E.coli data, but the current model results agree well enough with our measured E.coli concentrations (NSE equals 0.69 and 0.66 for calibration and validation respectively). Based on the pathogen source estimations, point (direct) sources are identified to be the most important microbial pollution sources. Pollution from upstream areas is also important, while non-point (diffuse) sources play a role mostly during the periods with high discharge. Our study underlines the importance of wastewater treatment and manure management both in and upstream of the study area. Studies like ours were lacking in developing countries like Pakistan and can be used for scenario analyses in the region (Chapter 4). The model can be useful in microbial water quality assessments in other watersheds and for pathogenic microorganisms, such as Cryptosporidium and Rotavirus.

    The calibrated and validated SWAT bacterial model (Chapter 4) was used to assess E.coli concentrations in a comprehensive scenario analysis (Chapter 5). We developed two future scenarios based on state-of-the-art approaches, using the Shared Socio-economic Pathways (SSPs), RCPs and own assumptions in line with the SSP storylines. We took the modelled E.coli concentrations from Chapter 4 as baseline scenarios and defines two future scenarios as Scenario_1 (sustainability scenario) and Scenario_2 (uncontrolled scenario). These scenarios represent different socio-economic development and climate change. The two scenarios were developed by combining SSP1, a sustainable, equitable and environmentally focussed world with RCP4.5 (limed climate change) in Scenario_1, and SSP3 (a divided world, with no interest in the environment) with RCP8.5 (strong climate change) in Scenario_2. Currently, no wastewater treatment plant exists in the basin, because the 2010 floods destroyed the available plants. We assumed excellent and poor wastewater and manure treatment for 2050s and 2100s for Scenario_1 and Scenario_2 respectively, in line with the storylines. Scenario_2 resulted in higher E.coli concentrations compared to the baseline scenarios due to high population growth, poor wastewater and manure treatment and land-use changes. However, microbial water quality was found to improve under Scenario_1. This was achieved by implementing improved and technologically advanced wastewater treatment and manure management. Future concentrations were found to be between 0.6% and 7% of the baseline concentrations depending on the treatment technology used (Chapter 5). This study highlights the need for substantial improvements in wastewater and manure treatment systems in the Kabul River Basin to assure future E.coli concentrations in water sources will be within the limits of WHO and US-EPA regulations for drinking and bathing water quality. The primary treatment facility that is currently installed is a good start, but insufficient to strongly reduce concentrations. Hence major investments are required to install technologically advanced wastewater treatment and manure treatment plants to cut-down the current contamination level of Kabul river.

    My PhD thesis provides a base for devising optimal coping strategies that are essential for the sustainability of hydrological resources under socio-economic developments and climate-change impacts. The results of our research are helpful to further assess alternative water quality management options. The outcomes of this study also increase the knowledge in the field of microbial fate and transport in water resources in a developing country like Pakistan, where such studies are lacking. A limited number of previous studies on global change impacts on microbial contamination of surface water in other areas of the world focused only on the climate-change impacts on microbial water quality. This is the first study to evaluate the influence of combined socio-economic and climate-change impacts on E.coli concentrations in the Kabul River Basin. The developed SWAT model and scenario analysis can be used for other contaminants, such as nutrients, pesticides and heavy metals. Our study can be a first step to improve water quality of the Kabul River Basin by providing tools for water managers and health specialists to improve the water quality and reduce the risks related to the use of contaminated water resources. This study will be useful not only in this region, but also for other regions of the world with similar microbial water contamination issues.

    Assessing the impact of socio-economic development and climate change on faecal indicator bacteria in the Betna River, Bangladesh
    Islam, Majedul - \ 2017
    Wageningen University. Promotor(en): R. Leemans, co-promotor(en): N. Hofstra. - Wageningen : Wageningen University - ISBN 9789463436304 - 137
    climatic change - environmental impact - water quality - rivers - contamination - bacteria - coliform bacteria - faecal coliforms - bangladesh - south asia - klimaatverandering - milieueffect - waterkwaliteit - rivieren - besmetting - bacteriën - coliformbacteriën - fecale coliformen - bangladesh - zuid-azië

    Consumption of water that is contaminated with pathogens still causes high numbers of death and disease. Understanding the factors that influence the dynamic distribution of waterborne pathogens is important, as this will help understanding improvements and possible solutions. Such understanding is particularly important in a developing country like Bangladesh, where large proportions of the population often have little or no access to clean water. Despite the high relevance for public health, few studies currently exists on the fate and transport of pathogens and the so-called Faecal Indicator Bacteria (FIB, e.g. E. coli, enterococci) in (sub)tropical systems. FIB are susceptible to shifts in water flow and quality. The predicted increases in rainfall and floods due to climate change will exacerbate the faecal contamination scenarios. This could be further compounded by the rapid change in socio-economic conditions (population growth, urbanization, sanitation and agricultural management) in the developing countries. Therefore, to reduce future health risks, understanding the influence of changes in socio-economic conditions and climate on microbial dynamics is important.

    Very few studies have quantified the relationship between the waterborne pathogens/FIB concentrations and climate and socio-economic changes. In this study a process-based model was developed and a scenario analysis was performed based on the new combined climate and socio-economic changes scenarios, to assess the present and future river hydrodynamics, FIB sources, die-off processes and concentrations. We used FIB, because measuring FIB are cheaper than pathogens. FIB are usually not pathogenic but their presence indicates the likely presence of waterborne pathogens. These pathogens are expected to respond to climate change in a comparable way to FIB. The present study is based on the Betna River basin in southwestern Bangladesh, where faecal contamination is not monitored and very little knowledge exists on the distribution of contaminants.

    First of all, FIB concentrations of the river water were measured to identify the river’s faecal contamination levels that can be used to validate the water-quality model. In the study area, wastewater is not treated and this untreated wastewater is discharged directly into the river. This is evident from the measured FIB data. In 88% of the E. coli and all enterococci samples, the USEPA bathing water quality standards were violated (Chapter 2). Such violation indicates potential health risks associated with the use of the river water for domestic, bathing and irrigation purposes. The correlation between environmental variables (water temperature, precipitation and salinity) and FIB concentrations was also determined. A positive correlation was found with water temperature and precipitation, and a negative correlation with salinity. The positive correlation with temperature is due to the co-occurrence of high summer temperature with abundant monsoon rainfall. The positive correlation with precipitation can be explained by the increased runoff from agricultural lands and urban areas. This runoff contains many bacteria. In the study area, during the rainy season (July to September) precipitation increases and as a result water salinity decreases. The observed negative correlation with salinity is more likely due to the typical weather patterns during the rainy season when low salinity coincides with increased precipitation and high temperature, than to salinity dependent die-off of bacteria. A regression model was applied that explained almost half of E. coli and enterococci variability in river water. This, however, only considers water temperature and precipitation (Chapter 2).

    Then, the present and future hydrodynamics of the river were simulated using a two dimensional hydrodynamic model (MIKE 21 FM). Although the main goal of this thesis is to assess the river’s present and future FIB concentrations, the reasons for this hydrodynamic modelling are twofold. Firstly, outputs of the hydrodynamic model are used as input into the water-quality model (Chapter 4). Secondly, hydrodynamics (i.e. water level and discharge) are simulated because increased water level and discharge together with sea level rise stimulate floods in the river basin. These floods are related to outbreaks of waterborne diseases. The modelled results corresponded very well with the measured water levels and discharges. The model was applied to simulate baseline and future water levels and discharge for Representative Concentration Pathway RCP4.5 and RCP8.5 scenarios using bias-corrected downscaled data from two climate models (IPSL-CM5A and MPI-ESM). The model results showed an expected increase in water level up to 16% by the 2040s and 23% by the 2090s (Chapter 3). The monsoon daily maximum discharge was expected to increase up to 13% by the 2040s and 21% by the 2090s. These model results also showed that the duration of the water level above the danger level and extreme discharge periods can increase by half a month by the 2040s and over a month by the 2090s. The coincidence of the water danger level with extreme discharge may cause disastrous floods in the study area.

    Next, the hydrodynamic model was coupled with a water-quality module (ECOLab). The fate and transport of FIB was simulated, the influence of different processes tested and the contribution from different sources to the total contamination quantified (Chapter 4). The model outputs corresponded very well with the measured FIB data. The present river microbial water quality based on measured and simulated results indicated, once again, noncompliance with bathing water standards. Primary and secondary levels of wastewater treatment were not sufficient to reach the standards most of the time, and discharges from sewer drains and incoming concentrations from the upstream boundary were found to be a major cause of water contamination. Tide, wind and diffuse sources (urban and agricultural runoff) contributed little. The high FIB inputs from the upstream open boundary come from untreated point source discharges from upstream urban areas and accumulation of diffuse contaminants from the large upstream areas. Therefore, this study underlines the need for establishment of wastewater treatment plants both in the studied basin and upstream urban areas. This study provides insight into bacterial fate and transport mechanisms, contribution of different sources to the faecal contamination and applicability of wastewater treatment in a river of a subtropical developing country where this type of study is lacking. Uncertainties are related to the lack of high temporal resolution measured FIB data and the lack of available data for contaminant loads from septic tank leakages, open defecation and sediment resuspension. However, the model well captured the measured FIB variability, suggesting that it can be applied for microbial water quality assessments in other watersheds of the world with similar characteristics.

    The developed model could be an ideal tool to forecast future impacts of climate and socioeconomic changes on FIB fate, transport and dynamics. Finally, future FIB concentrations were simulated using the coupled hydrodynamic and microbial model (MIKE 21 FM-ECOLab) and scenario analysis (Chapter 5). Scenarios have been developed building on the most recent Shared Socio-economic Pathways (SSPs) and Representative Concentration Pathways (RCPs) scenarios from the Intergovernmental Panel on Climate Change (IPCC). We developed a baseline scenario (October 2014–September 2015) reflecting the current conditions and two future scenarios, S1 (sustainability scenario) and S2 (uncontrolled scenario) mimicking different future developments of socio-economic (population, urbanization, sanitation, wastewater treatment development, land use) and climate-change factors (temperature, precipitation and sea-level rise). In S1 RCP4.5 was combined with socio-economic scenarios SSP1, and for S2 RCP8.5 was combined with SSP3 (S2). Assumptions on sanitation, waste water treatment and agricultural management in line with the storylines were made to quantify future changes in FIB concentrations and consequent health risk. Different future scenarios were found to have substantial impact on FIB concentrations in the river. By the 2090s, FIB concentrations are expected to decrease by 98% or increase by 75% for the sustainability scenario and uncontrolled scenario respectively. An uncontrolled future resulted in a deterioration of microbial water quality due to socio-economic developments, such as higher population growth, land-use change and increased sewage discharges and changes in rainfall patterns. Microbial water quality strongly improved under a sustainable climate and improved sewage treatment. FIB concentrations were much more sensitive to changes in socio-economic factors than to changes in climatic factors. This underlines the importance of socio-economic factors in assessing and improving microbial water quality.

    The results show the importance of improvements in sanitation and wastewater treatment in the Bangladeshi Betna River basin to ensure that future FIB concentrations in the river comply with the US-EPA bathing water quality standards. Major investments to construct wastewater treatment plants are necessary to compensate for the population growth and increased the volume of wastewater treatment. Although the current level of contamination is already too high, without wastewater treatment the water quality will further deteriorate.

    The thesis assesses the present and future FIB dynamics in the Betna River through sampling, statistical and process-based modelling, and scenario analysis. The results contribute to increase the knowledge base on the dynamic distributions of the FIB in surface water in a developing country and in a subtropical system, where this type of study is lacking. It also reduces the knowledge gaps regarding future flooding scenarios at the local scale. While some earlier studies focused on only assessing climate-change impacts on microbial water quality, this study for the first time assessed the influence of combined climate and socio-economic scenarios (using scenarios based on the new SSP-RCP scenario matrix) on river FIB concentrations. This combined modelling and scenario approach enables the assessment of faecal contamination sources and dynamics at present and in the future. The developed model and scenario analysis approach provides a basis for the water managers to reduce the widespread faecal contamination and the risks of waterborne disease outbreaks, which are still a leading cause of deaths in developing countries.

    Role of reservoir operation in sustainable water supply to Subak irrigation schemes in Yeh Ho River Basin
    Yekti, Mawiti Infantri - \ 2017
    Wageningen University. Promotor(en): E. Schulz, co-promotor(en): I. Nyoman Norken; László Hayde. - Leiden : CRC Press/Balkema - ISBN 9781138065437 - 250
    irrigation systems - irrigation - water supply - sustainability - basin irrigation - indonesia - rivers - irrigatiesystemen - irrigatie - watervoorziening - duurzaamheid (sustainability) - kombevloeiing - indonesië - rivieren

    A Subak irrigation scheme, primarily in Bali, Indonesia concerns an irrigation system of which the construction, operation and management are based on agreed principles of technology, management of agriculture and religious community. Subak systems have been well known since the 9th Century. As a manifestation of the Cultural Landscape of Bali Province the Subak schemes are since June, 2012 included in the World Heritage List of UNESCO. These systems are managed by a Subak Association based on the Tri Hita Karana philosophy - harmony between human beings and God, harmony between people and nature, and harmony between people and people.

    The problem of insufficient water in the dry season developed in the Yeh Ho River Basin. Because of this the main objective of this study was to develop an optimal reservoir operation strategy in relation to the water supply of the Subak irrigation schemes, capable to support agricultural productivity at upstream, midstream and downstream level. Based on a Generic Algorithm the RIBASIM model was applied using the dependable 80% of discharge and shifting the start of land preparation. The results provide evidence that the cropping pattern of the fifth scenario results in an overall optimal agriculture production of the Subak schemes. The recoverable flow considered in the river basin scheme model plays an important role in the optimisation. Nevertheless, if a normal hydro-climate occurs, the other scenarios, especially the first scenario, can be applied as well. This reflects the applicability of the Tri Hita Karana philosophy on harmony among people and harmony among people and nature.

    From harmful to useful algae
    Blaas, Harry - \ 2017
    Wageningen University. Promotor(en): Carolien Kroeze. - Wageningen : Wageningen University - ISBN 9789463430357 - 117
    algae - algae culture - adverse effects - nitrogen - phosphorus - rivers - eutrophication - waste water treatment - europe - algen - algenteelt - nadelige gevolgen - stikstof - fosfor - rivieren - eutrofiëring - afvalwaterbehandeling - europa

    Eutrophication of coastal waters is a worldwide phenomenon. This study focuses on eutrophication in the coastal waters of Europe. Eutrophication is mainly a result of the increased transport of nutrients from watersheds by rivers to the coastal waters. Nutrient losses from watersheds are generally from agriculture, sewage, atmospheric deposition and from natural sources. In case of an overload of nutrients in the coastal waters, algal blooms may develop which increase the risk of hypoxia, fish mortality, and loss of biodiversity.

    Algae can also be useful. They are increasingly considered an interesting product. For instance, micro-algae can be grow on land to produce proteins, lipids and fatty acids. Some studies indicate that micro-algae can be an important feedstock in the future for, for instance, the production of biodiesel. Moreover, macro-algae can be produced in seawater in sea farms. Macro-algae can be edible, or be used as a feedstock. By yielding macro-algae, nutrients are removed from the water, reducing coastal eutrophication.

    The objective of this study is to analyse past and future trends in nutrient export by rivers to European seas with a focus on the role of algae. Three types of algae will be distinguished: (1) harmful algal blooms in coastal seas, (2) cultivation of micro-algae on land for the production of proteins, lipids and fatty acids, and (3) cultivation of multi cellular algae in seaweed farms for human consumption or other products.

    To meet the objective the following research questions are addressed:

    RQ1 To what extent do N and P loads exceed levels that minimize the risk of harmful algal blooms, and what are the relative shares of sources of N and P in rivers of the European Union?

    RQ2 What are the potential consequences of large-scale land-based production of biodiesel from cultivated micro-algae in Europe for coastal eutrophication?

    RQ3 Would it possible to cultivate and process micro-algae in a factory, and what is the environmental performance?

    RQ4 To what extent can seaweed farming in combination with nutrient management in agriculture and waste water treatment reduce the potential for coastal eutrophication?

    These questions are answered through model analyses. The Global NEWS (Nutrient Export from WaterSheds) model simulates river export of nutrients as function of human activities on land. It includes more than 6000 rivers worldwide. It can be used to quantify nutrient flows from land to sea for the years 1970, 2000, 2030 and 2050. For future years four scenarios have been implemented. One of these scenarios is named Global Orchestration and mostly used as a reference in this thesis. This scenario assumes a globalised world, with a reactive approach towards environmental problems. The model was released in 2010, has been validated for the years 1970 and 2000. The nutrients considered in the model are nitrogen (N) and phosphorus (P). In this thesis Global NEWS is used to calculate transport of nutrients to the coastal waters of Europe. The model uses ICEP (Indicator for Coastal Eutrophication Potential) values at the river mouths as an indicator for potentially harmful effects of nutrient enrichment. These ICEP values reflect the ratio of nitrogen and phosphorus to silica in coastal seas. A positive ICEP value indicates that nitrogen or phosphorus levels are too high, favouring conditions for potentially harmful algae to bloom.

    In chapter 2 Global NEWS is used to calculate the transport of nutrients and ICEP values for 48 European rivers for the years 2000 and 2050. The model calculates a positive ICEP for 38 rivers in the year 2000, and for 34 rivers in the year 2050. This indicates that current policies are not so effective in reducing the river transport of nutrients. For polluted rivers the anthropogenic sources of the nutrients are investigated. For most rivers the dominant polluting sources are agriculture or sewage. The results indicate that a basin-specific policy is needed to reduce the risks of coastal eutrophication.

    In chapter 3 the focus is on useful algae: micro-algae cultivation on land for, for instance, biodiesel production. The consequences of large-scale production of biodiesel on nutrient export by rivers to the European coastal waters are investigated. A scenario is developed assuming that a production of 0.4 billion m3 diesel from cultivated micro-algae. The cultivation is assumed to be in the open air, for instance in ponds or in closed tube systems. Such production levels would need a land surface area as large as Portugal. The Global NEWS model is used to calculate the amount of waste water from micro-algae production that will be transported to the coastal waters in this scenario. The results indicate that large-scale cultivation of micro-algae on land can become a source of nutrient pollution in rivers. In the scenario with large-scale micro-algae cultivation the future transport of nitrogen and phosphorus is considerably higher than in the reference scenario. To ensure sustainable production of biodiesel from micro-algae it is important to develop cultivation systems with low nutrient losses to the environment.

    Chapter 4 presents a design of a factory for the cultivation and processing of micro-algae in an environmentally sound way. The factory does not use fossil fuels and applies maximum recycling of water and nutrients. In this factory it is possible to produce lipids, carbohydrates, proteins and minerals. The factory can be built on any piece of land, so there is no need to use arable land. The factory is independent of weather and climate. Energy can be delivered by wind mills. In this chapter an example of producing diesel in the factory is shown. In the 12 stories factory with a cultivation area of 1 hectare, 810 ton micro-algae can be cultivated per year. This is enough for the production of 386 ton diesel per year.

    Chapter 5 focuses on mitigation of eutrophication in European coastal waters. A scenario is presented assuming different types of measures. The scenario first assumes that nutrient use efficiencies in agriculture are higher than today, and that waste water treatment in sewage systems is improved. In addition, it assumes that all excess N and P in coastal waters is harvested in seaweed farms producing edible macro-algae. In our scenario for 2050 there is seaweed farming in the coastal waters of 34 rivers mouths in Europe .NEWS The areas needed to ensure that ICEP values remain below 0 (low potential for coastal eutrophication) range between 0 and 952 km2 per river mouth.

    This thesis shows that algae can be both harmful and useful. River export of nutrients can lead to coastal eutrophication increasing the risks of harmful algal blooms. On the other hand, micro-algae can be produced without environmental harm on land, and macro-algae can be useful in reducing pollution levels in coastal seas. This thesis could serve as a basis for environmental policies to stimulate the production of these useful algae. The methods to mitigate algal blooms and to use algae in a sustainable way in this thesis are also useful for other parts of the world.

    River export of nutrients to the coastal waters of China: the MARINA model to assess sources, effects and solutions
    Strokal, Maryna - \ 2016
    Wageningen University. Promotor(en): Carolien Kroeze, co-promotor(en): S. Luan; Lin Ma. - Wageningen : Wageningen University - ISBN 9789462579729 - 226
    cum laude - nutrients - rivers - coastal water - models - eutrophication - coastal areas - water pollution - china - voedingsstoffen - rivieren - kustwateren - modellen - eutrofiëring - kustgebieden - waterverontreiniging - china

    Rivers export increasing amounts of nitrogen (N) and phosphorus (P) to the coastal waters of China. This causes eutrophication problems that can damage living organisms when oxygen levels drop and threaten human health through toxic algae. We know that these problems result from human activities on land such as agriculture and urbanization. However, the relative importance of these human activities for river export of nutrients to Chinese seas is not well studied. There are two important issues that need further investigation: the relative importance of upstream pollution on downstream impacts and the relative importance of typical sources of nutrients in Chinese rivers that are often ignored in existing modeling studies.

    My PhD thesis, therefore, aims to better understand trends in river export of nutrients to the coastal waters of China by source from sub-basins, and the associated coastal eutrophication. To this end, I developed the MARINA model: Model to Assess River Inputs of Nutrients to seAs. For this, I used the existing Global NEWS-2 model (Nutrient Export from WaterSheds) as a starting point.

    I formulated five sub-objectives to achieve the main objective:

    To analyze the original Global NEWS-2 model for river export of nutrients and the associated coastal eutrophication (Chapter 2);

    To develop a sub-basin scale modeling approach to account for impacts of upstream human activities on downstream water pollution, taking the Pearl River as an example (Chapter 3);

    To quantify the relative share of manure point sources to nutrient inputs to rivers at the sub-basin scale (Chapter 4);

    To quantify the relative share of sources to river export of nutrients at the sub-basin scale (Chapter 5);

    To explore optimistic futures to reduce river export of nutrients and coastal eutrophication in China (Chapter 6).

    The study area includes rivers draining roughly 40% of China. This includes the most densely populated areas, and areas with intensive economic activities. The rivers include the Yangtze (Changjiang), Yellow (Huanghe), Pearl, Huai, Hai and Liao. In the MARINA model, the drainage areas of the large Yangtze, Yellow and Pearl rivers are divided into up-, middle- and downstream sub-basins. The principle of the sub-basin approach of MARINA is that nutrients from human activities are transported by tributaries to outlets of sub-basins and then to the river mouth (coastal waters) through the main channel. The model takes into account nutrients that are partly lost or retained during transport towards the river mouth. The model quantifies river export of nutrients by source from sub-basins for 1970, 2000 and 2050.

    The main six findings of the MARINA results for China are:

    Finding 1: Dissolved N and P export by Chinese rivers increased by a factor of 2-8 between 1970 and 2000;

    Finding 2: The potential for coastal eutrophication was low in 1970 and high in 2000 in China;

    Finding 3: Most dissolved N and P in Chinese seas is from middlestream and downstream human activities;

    Finding 4: Manure point sources are responsible for 20-80% of dissolved N and P in Chinese rivers;

    Finding 5: In the future, river export of nutrients may increase in the Global Orchestration (GO) scenario of the Millennium Ecosystem Assessment. Current policy plans (CP scenario) may not sufficient to avoid this increase;

    Finding 6: In optimistic scenarios (OPT-1 and OPT-2), the potential for coastal eutrophication is low in 2050, mainly as a result of assumed full implementation of: (1) high recycling rates of animal manure (OPT-1 and OPT-2), and (2) high efficiencies of nutrient removal in sewage systems (OPT-2, see Figure 1).

    Figure 1. Illustration of future scenarios for coastal water quality in China. GO is Global Orchestration of the Millennium Ecosystem Assessment and assumes environmental actions that are either absent or ineffective in reducing water pollution. CP is based on GO, but incorporates the “Zero Growth in Synthetic Fertilizers after 2020” policy. OPT-1 and OP-2 are optimistic scenarios that assume high nutrient use efficiencies in agriculture (OPT-1, OPT-2) and sewage (OPT-2).

    My PhD thesis reveals novel insights for effective environmental policies in China. It shows the importance of manure point sources in water pollution by nutrients. Clearly, managing this source will likely reduce coastal eutrophication in the future. Furthermore, the implementation of advanced technologies is essential when dealing with urban pollution. My PhD thesis may also be useful for other world regions with similar environmental problems as in China. The new, sub-basin scale MARINA model is rather transparent and thus can be applied to other large, data-poor basins that may benefit from the allocation of effective management options. With this I hope to contribute to future availability of sufficiently clean water for next generations, not only in China, but also in other world regions.

    Legitimatie van de nevengeul voor de Waal langs Varik : constructies van risico’s uit onzekerheden die redenen geven voor voorzorg : publieksrapport
    During, R. ; Pleijte, M. ; Vreke, J. - \ 2016
    Wageningen : Wageningen UR, Wetenschapswinkel (Rapport / Wetenschapswinkel Wageningen UR 324a) - ISBN 9789462578180 - 39
    klimaatverandering - rivieren - waal - hoogwaterbeheersing - afvoer - burgers - waterbeheer - rivierregulering - climatic change - rivers - river waal - flood control - discharge - citizens - water management - river regulation
    “Wat is de legitimatie van de geprojecteerde nevengeul van de Waal bij Varik en Heesselt?” In het onderzoek dat heeft plaatsgevonden is specifiek gekeken naar de onderbouwing van de maatgevende afvoer van 18.000 m3/s bij Lobith eind 21e eeuw en naar de wijze waarop er in de planvorming met de onzekerheden rondom de maatgevende afvoer is omgegaan. Daarbij is in eerste instantie gekeken naar de onderbouwing die door de provincie en door het stafbureau van de Deltacommissaris is aangeleverd aan de bewoners. In tweede instantie moest er veel ruimer gezocht worden naar onderbouwende publicaties, want die onderbouwing had het karakter van “work in progress”.
    Legitimatie van de nevengeul voor de Waal langs Varik : constructies van risico’s uit onzekerheden die redenen geven voor voorzorg : achtergrondrapport
    During, R. ; Pleijte, M. ; Vreke, J. - \ 2016
    Wageningen : Wageningen UR, Wetenschapswinkel (Rapport / Wetenschapswinkel Wageningen UR 324b) - ISBN 9789462573895 - 141
    klimaatverandering - rivieren - waal - hoogwaterbeheersing - afvoer - burgers - waterbeheer - rivierregulering - climatic change - rivers - river waal - flood control - discharge - citizens - water management - river regulation
    “Wat is de legitimatie van de geprojecteerde nevengeul van de Waal bij Varik en Heesselt?” In het onderzoek dat heeft plaatsgevonden is specifiek gekeken naar de onderbouwing van de maatgevende afvoer van 18.000 m3/s bij Lobith eind 21e eeuw en naar de wijze waarop er in de planvorming met de onzekerheden rondom de maatgevende afvoer is omgegaan. Daarbij is in eerste instantie gekeken naar de onderbouwing die door de provincie en door het stafbureau van de Deltacommissaris is aangeleverd aan de bewoners. In tweede instantie moest er veel ruimer gezocht worden naar onderbouwende publicaties, want die onderbouwing had het karakter van “work in progress”.
    Alarming nutrient pollution of Chinese rivers as a result of agricultural transitions
    Strokal, Maryna ; Ma, Lin ; Bai, Zhaohai ; Luan, Shengji ; Kroeze, Carolien ; Oenema, Oene ; Velthof, Gerard ; Zhang, Fusuo - \ 2016
    Environmental Research Letters 11 (2016)2. - ISSN 1748-9326
    agricultural transitions - China - integrated modeling - nutrient pollution - rivers

    Transitions in Chinese agriculture resulted in industrial animal production systems, disconnected from crop production. We analyzed side-effects of these transitions on total dissolved nitrogen (TDN) and phosphorus (TDP) inputs to rivers. In 2000, when transitions were ongoing, 30%-70% of the manure was directly discharged to rivers (range for sub-basins). Before the transition (1970) this was only 5%. Meanwhile, animal numbers more than doubled. As a result, TDN and TDP inputs to rivers increased 2- to 45-fold (range for sub-basins) during 1970-2000. Direct manure discharge accounts for over two-thirds of nutrients in the northern rivers and for 20%-95% of nutrients in the central and southern rivers. Environmental concern is growing in China. However, in the future, direct manure inputs may increase. Animal production is the largest cause of aquatic eutrophication. Our study is a warning signal and an urgent call for action to recycle animal manure in arable farming.

    Wild geese of the Yangtze River : their ecology and conservation
    Zhang, Y. - \ 2016
    Wageningen University. Promotor(en): Herbert Prins; Fred de Boer; L. Cao. - Wageningen : Wageningen University - ISBN 9789462576049 - 147
    geese - anatidae - anser - animal ecology - wildlife management - nature conservation - hydrology - habitat selection - rivers - china - ganzen - anatidae - anser - dierecologie - wildbeheer - natuurbescherming - hydrologie - habitatselectie - rivieren - china

    Habitat selection is a process in which organisms decide to choose a suitable site for nesting, roosting or foraging. The question where the organisms are, and when they will leave are two of the fundamental questions frequently asked by ecologists. Habitat selection is affected by various abiotic and biotic determinants, varying over different spatial and temporal scales. In addition, an animal’s body size, determining its daily demands and its digestion capacity, plays an important role in foraging and habitat selection. This is because forage quality often decreases with increasing forage quantity. Therefore, herbivores often face a trade-off between forage quality and quantity. Although studies on habitat selection have offered substantial insights into the effect of various ecological factors, myriad effects of habitat and its’ surrounding are still not clearly understood, as former studies concerning this topic normally focus on a single species or a single spatial scale.

    Migrating goose species are herbivorous with more or less similar habitat requirements and hence often mix in the field. Studying habitat selection of different goose species is attractive as they are from the same guild but differ in body size. In this thesis, I study the effects of various variables on habitat selection of different Anatidae species over different spatial scales, answering the question how ecological and anthropogenic variables affect Anatidae species habitat selection and population sizes and if these effects vary over different spatial scales.

    First, I studied the habitat selection of Anatidae species under the condition with and without interference competition using an experimental approach in Chapter 2. To do this, I offered geese and ducks foraging patches with various swards heights. My results showed that all three species acquired the highest nitrogen intake at relatively tall swards (on 6 or 9 cm, but not on 3 cm) when foraging in single species flocks in the functional response experiment. When they were offered foraging patches differing in sward height with and without competitors, their mean percentage of feeding time did not change, whereas all species increased their percentage of time being vigilant except for the dominant swan goose. All species utilized strategies that increased their peck rate on patches across different sward heights when foraging together with other species, resulting in the same instantaneous and nitrogen intake rate than when foraging in a single species flocks. My results suggest that variation in peck rate over different swards height permits Anatidae herbivores to increase nitrogen intake under competition to compensate for the loss of intake, illustrating the importance of behavioural plasticity in heterogeneous environments when competing with other species for resources.

    In Chapter 3, using a correlative field study, I analysed the habitat selection of two differently sized grazing goose species at site level. I found that both species selected lower lying area where the swards became recently exposed, due to receding water levels. However, the smaller species was more sensitive to this elevation gradient. Moreover, sward height negatively affected both species habitat selection with a stronger effect on the smaller species. This result highlighted the importance of body size on facilitating species coexistence and habitat segregation. Not in agreement with the results from most experimental studies, I found that nitrogen content did not influence habitat selection of both species. This conflicting result suggests that additional factors should be carefully considered when applying outcomes from experimental studies to field situations.

    In Chapter 4, I studied habitat selection of the two goose species at a lake level by analysing the effect of ecological and anthropogenic variables. My results supported the individual-area relationship as only patch area had a significant effect on both species habitat selection, and other variables that were related to food availability and disturbance, were not significant. In addition, a facilitation effect of grazing livestock on geese habitat selection was detected, indicating that larger grazing herbivores can facilitate geese foraging by removing the taller and lower quality food from the top. As patch area size in wetlands is directly linked to water levels fluctuations, this result demonstrated that modifying hydrological regimes can enlarge the capacity of wetlands for migratory birds.

    In Chapter 5, I further expanded my study area to the flood plain level of the Yangtze, testing for the effect of various abiotic and biotic variables on several Anatidae species habitat selection and population trends. I showed that slope and climate factors were the most important ones affecting habitat selection and distribution of Anatidae species. Furthermore, I demonstrated that the current protection policies may not stop the declining population trends but might buffer to some extent against a rapid decline in numbers in wetlands with a higher level protection status. This result points out that the conservation effectiveness is still low and larger conservation efforts are urgently needed to maintain the Anatidae populations, especially in wetlands with a lower level protection status. I recommend several protection measures to stop the decline of Anatidae species in wetlands of the Yangtze River flood plain and I called for more research efforts in this area in particularly, but also at a larger scale, the entire East Asian-Australasian Flyway.

    In Chapter 6, I synthesized these results and draw conclusions from the preceding chapters, and highlighted the importance of spatial scales when studying the effect of abiotic and biotic variables on animals’ habitat selection. I also propose to modify hydrological regimes, aimed at creating enhanced habitat and improved forage accessibility conditions over the entire wintering period for herbivorous birds species in the Yangtze River flood plain. In summary, this thesis offers a framework for the effects of various variables on habitat selection and population sizes of herbivorous Anatidae species over different spatial scales, and a scientific basis for policy-makers and managers to enhance the efficiency of conservation actions in wetlands along the Yangtze River flood plain and also for similar ecological systems.

    Een evaluatie van de maatlatten R6 en R7 voor de Kader Richtlijn Water
    Griffioen, A.B. ; Vries, I. de - \ 2016
    IMARES (Rapport / IMARES C087/15) - 28
    rivieren - kaderrichtlijn water - waterbeheer - classificatie - waterkwaliteit - aquatische ecologie - monitoring - rivers - water framework directive - water management - classification - water quality - aquatic ecology - monitoring
    De watertypes R6 en R7 in de Kader Richtlijn Water (KRW) classificering verschillen qua grootte van het waterlichaam en structuur. Het watertype R7 staat voor de grote rivieren met een hoofdstroom en nevengeulen. Rivieren als de Rijn, Waal en IJssel zijn hier voorbeelden van. Het watertype R6 staat voor langzaam stromende kleinere rivieren. In de praktijk kunnen beide riviertypen in elkaar overgaan en is het goed mogelijk dat het visbestand een grote overlap kent, maar volgens verschillende maatlatten worden beoordeeld. Dit onderzoek heeft tot doel het inzichtelijk maken van de indeling in beide watertypes. Ook wordt er gekeken naar de verschillen tussen de watertypen R6 en R7.
    Toestand vis en visserij in de zoete Rijkswateren 2015 Deel III: Data
    Keeken, O.A. van; Hoppe, M. van; Boois, I.J. de; Graaf, M. de; Griffioen, A.B. ; Lohman, M. ; Os-Koomen, E. van; Westerink, H.J. ; Wiegerinck, J.A.M. ; Overzee, H.M.J. van - \ 2016
    IJmuiden : Wageningen Marine Research (Rapport / Wageningen Marine Research C116/16) - 543 p.
    zoet water - aquatische ecologie - vissen - monitoring - ijsselmeer - randmeren - rivieren - inventarisaties - fresh water - aquatic ecology - fishes - monitoring - lake ijssel - randmeren - rivers - inventories
    Piekberging en voorraadberging in Rivierenland : een inventarisatie van geschikte gebieden voor piekberging en voorraadberging in het beheergebied van Waterschap Rivierenland
    Massop, H.Th.L. ; Jansen, P.C. ; Hattum, T. van; Kwakernaak, C. - \ 2015
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2685) - 49
    wateropslag - waterbeheer - watervoorraden - nederlandse wateren - rivieren - waterverzadiging - gelderland - water storage - water management - water resources - dutch waters - rivers - waterlogging - gelderland
    Alterra Wageningen UR heeft, als een van de partijen in het project RichWaterWorld (RWW), onderzoek gedaan naar piekberging en voorraadberging in Het Waterrijk, een gebied dat onderdeel is van Park Lingezegen dat tussen Arnhem en Nijmegen wordt aangelegd. Omdat door klimaatverandering de kansen op wateroverlast en watertekorten toenemen, is ook elders in Nederland een toenemende behoefte aan bergingsgebieden die kunnen worden ingezet voor piekberging en voorraadberging. Voor Rivierenland is met GIS-bewerkingen geïnventariseerd waar geschikte gebieden voor beide vormen van waterberging liggen.
    Dioxines en PCB's in Chinese wolhandkrab; invloed van grootte en variatie door het seizoen
    Kotterman, M.J.J. ; Vries, P. de; Leeuwen, S.P.J. van; Hoogenboom, L.A.P. - \ 2015
    IMARES Wageningen UR (Rapport / IMARES ) - 43
    krabben (schaaldieren) - decapoda - schaaldieren - dioxinen - polychloorbifenylen - rivieren - meren - nederland - crabs - decapoda - shellfish - dioxins - polychlorinated biphenyls - rivers - lakes - netherlands
    De monitoringsstudies naar de vervuilingsgraad van Chinese Wolhandkrab (WHK) die vanaf 2010 in Nederlandse wateren worden uitgevoerd tonen aan dat de WHK sterk vervuild kan zijn met polychloordibenzo-p-dioxines en -furanen (PCDD/F's, verderop aangeduid als 'dioxines'), met dioxine-achtige polychloorbifenylen (dl-PCB's) en met niet-dioxine achtige PCB’s (ndl-PCB’s). Deze contaminanten bevinden zich vooral in het vlees met hoge vetgehalten, de hepatopancreas (= middendarmklier) en gonaden (= geslachtsklier), vaak aangeduid met het 'bruine vlees' uit het lijf. Het witte spiervlees, uit poten, scharen en ook uit het lichaam, is vetarm en de concentraties dioxines en PCB’s zijn laag. Uit de voorgaande onderzoeken blijkt dat er een sterk geografische invloed is op de concentraties contaminanten in WHK; bijvoorbeeld WHK gevangen in de grote rivieren zijn sterker vervuild dan WHK uit het IJsselmeer. Over een eventuele tijdsafhankelijke variatie waardoor bijvoorbeeld gedurende het trekseizoen de concentraties contaminanten in de WHK sterk wisselen op een bepaalde locatie, is nog niets bekend. Er is wel reden om dat aan te nemen. WHK leggen in het trekseizoen grote afstanden af. De kans is daarom reëel dat de WHK die in een bepaald gebied worden gevangen van verschillende locaties afkomstig zijn, waardoor de concentraties contaminanten tussen individuele WHK kunnen verschillen.
    Toestand vis en visserij in de Zoete Rijkswateren: 2014 Deel I: Trends van de visbestanden, vangsten en ecologische kwaliteit ratio's
    Graaf, M. de; Boois, I.J. de; Griffioen, A.B. ; Overzee, H.M.J. van; Tien, N.S.H. ; Tulp, I.Y.M. ; Vries, P. de; Deerenberg, C.M. - \ 2015
    IMARES (Rapport / IMARES C199/15) - 102
    zoet water - aquatische ecologie - vissen - monitoring - rivieren - inventarisaties - visserij - visvangsten - vistuig - ijsselmeer - visstand - fresh water - aquatic ecology - fishes - monitoring - rivers - inventories - fisheries - fish catches - fishing gear - lake ijssel - fish stocks
    Het rapport “Toestand Vis en Visserij in de Zoete Rijkswateren” bestaat uit drie verschillende delen: “Trends”, “Methoden” en “Data”. In dit rapport (Deel I) worden (i) de trends in commercieel benutte vissoorten per VBC gebied, (ii) de trends in Habitatrichtlijnsoorten en (iii) de ecologische kwaliteitsratio’s vis gerapporteerd. Hiervoor is gebruik gemaakt van de gegevens die binnen de verschillende vismonitoringsprogramma’s op de Zoete Rijkswateren worden verzameld. In de rapportage zijn trendanalyses voor de verschillende commercieel benutte vissoorten en Habitatrichtlijn vissoorten gemaakt aan de hand van de beschikbare monitoringsgegevens. De gegevens van deze monitoringsprogramma’s worden gebruikt als indicatoren voor de ontwikkeling van de bestanden van de geanalyseerde soorten over verschillende tijdsperioden.
    Natuurrealisatie in het programma Ruimte voor de Rivier : Wat zijn de leerpunten van het programma Ruimte voor de Rivier voor combineren vanwater- en natuuropgaven?
    Hartgers, E.M. ; Buuren, M. van; Fontein, R.J. ; Hattum, T. van; Lange, H.J. de; Maas, G.J. - \ 2015
    Alterra, Wageningen-UR (Alterra-rapport 2687) - 75
    rivieren - natuurbescherming - natuurbeheer - natuurontwikkeling - hoogwaterbeheersing - nederland - rivers - nature conservation - nature management - nature development - flood control - netherlands
    In het Ruimte voor de Rivier-programma is ruime ervaring opgedaan in het combineren van hoogwaterveiligheidsopgaven met andere doelen, waaronder natuur. Het is een succesvol programma, dat grotendeels op tijd en binnen budget is uitgevoerd, met veel belangstelling vanuit het buitenland. Dit uitvoeringsprogramma is gebruikt om acht sleutelfactoren te identificeren die van belang zijn bij het realiseren van natuur in uitvoeringsprojecten. De acht sleutelfactoren zijn verdeeld over de categorieën Ambitie, Voldoen aan de wet en Daadkracht. Deze sleutelfactoren bevatten diverse aanbevelingen om natuur in toekomstige water gerelateerde uitvoeringsprojecten mee te nemen. Voor toekomstige uitvoeringsprojecten is het van cruciaal belang om in een vroege fase van een project kansen voor win-winsituaties voor natuur en water in beeld te krijgen. Daarbij is het cruciaal dat in het project de ‘dubbeldoelstelling’ natuurrealisatie en waterveiligheid expliciet benoemd wordt. Gezien de tijdsgeest en de insteek van het Deltaprogramma, dat meer dan het Ruimte voor de Rivierprogramma een sectorale insteek kent, is dit een toekomstige uitdaging.
    Toestand vis en visserij in de zoete Rijkswateren : Deel II: Methoden
    Sluis, M.T. van der; Tien, N.S.H. ; Griffioen, A.B. ; Keeken, O.A. van; Os-Koomen, E. van; Rippen, A.D. ; Wolfshaar, K.E. van de - \ 2015
    IJmuiden : IMARES (Rapport / IMARES C193/15) - 88
    zoet water - aquatische ecologie - vissen - monitoring - rivieren - inventarisaties - ijsselmeer - visvangsten - visserij - vistuig - fresh water - aquatic ecology - fishes - monitoring - rivers - inventories - lake ijssel - fish catches - fisheries - fishing gear
    Het rapport “Toestand Vis en Visserij in de Zoete Rijkswateren” bestaat uit drie delen. Dit rapport (Deel II) is een achtergronddocument waarin de gebruikte monitoringsmethodieken in de verschillende vis-monitoringen in de zoete Rijkswateren in detail worden beschreven. Meer informatie over trends en vangsten is te vinden in rapportages Deel I: Trends visbestanden, vangsten en ecologische kwaliteit ratio’s en Deel III: Data).
    Toestand vis en visserij in de zoete Rijkswateren: 2014 : Deel III: Data
    Boois, I.J. de; Hoek, R. ; Graaf, M. de; Griffioen, A.B. ; Keeken, O.A. van; Lohman, M. ; Os-Koomen, E. van; Westerink, H.J. ; Wiegerinck, J.A.M. - \ 2015
    IJmuiden : IMARES (Rapport / IMARES C194/15) - 511
    zoet water - aquatische ecologie - vissen - monitoring - rivieren - inventarisaties - ijsselmeer - visvangsten - visserij - vistuig - fresh water - aquatic ecology - fishes - monitoring - rivers - inventories - lake ijssel - fish catches - fisheries - fishing gear
    Dit rapport bevat een overzicht van de gegevens verzameld tijdens de vismonitoringen in de zoete rijkswateren. Het omvat de volgende bemonsteringen: - Open water vismonitoring IJssel- en Markermeer met actieve vistuigen - Oever vismonitoring IJssel- en Markermeer met actieve vistuigen - Vismonitoring in IJssel- en Markermeer met kieuwnetten - Diadrome vis Kornwerderzand Waddenzee op basis van fuikregistraties - Vismonitoring grote rivieren met actieve vistuigen - Vismonitoring zoete rijkswateren op basis van vangstregistratie aalvissers - Diadrome vismonitoring zoete rijkswateren op basis van fuikregistraties (sinds najaar 2012) - Vismonitoring grote rivieren op basis van zalmsteekregistraties - Vismonitoring randmeren met actieve vistuigen - Monitoring glasaal op intreklocaties.
    Bruinvis volgt spiering naar westerschelde
    Ramaker, R. ; Leopold, M.F. - \ 2015
    Resource: weekblad voor Wageningen UR 10 (2015)8. - ISSN 1874-3625 - p. 9 - 9.
    phocoenidae - milieubeleid - westerschelde - habitats - habitatgeschiktheid - osmerus - rivieren - wilde dieren - populatie-ecologie - phocoenidae - environmental policy - western scheldt - habitats - habitat suitability - osmerus - rivers - wild animals - population ecology
    In de Westerschelde zwemmen voor het eerst in decennia weer bruinvissen. De dieren jagen op de eveneens teruggekeerde trekvis spiering. Het is een succesverhaal van het Nederlands milieubeleid, zegt Mardik Leopold, onderzoeker van Imares Wageningen UR, die vandaag promoveert op onderzoek naar het eetgedrag van bruinvissen.
    Reguleringsmechanismen in het kustecosysteem van de Voordelta
    Kooten, T. van; Jansen, H.M. - \ 2015
    IJmuiden : IMARES (Rapport / IMARES C095/15) - 66
    aquatische ecosystemen - benthos - voordelta - kustwateren - zuidwest-nederland - aquatische gemeenschappen - visserij - bodemfauna - rivieren - aquatic ecosystems - benthos - voordelta - coastal water - south-west netherlands - aquatic communities - fisheries - soil fauna - rivers
    Wordt het benthos in het Voordelta kustecosysteem gereguleerd door bottom-up of top-down gerelateerde processen, en hoe zal dit systeem reageren op de maatregelen om de bodemberoerende visserij uit te sluiten in het Bodembeschermingsgebied.
    Perspectieven voor ecosysteemdiensten en natuur van een hoogwatergeul bij Varik Heesselt : een studie voor de NKN-casus Waterveiligheid Deltaprogramma
    Bos, M. ; Hartgers, E.M. ; Goossen, C.M. ; Groot, W.J.M. de; Kwakernaak, C. ; Maas, G.J. ; Levelt, O. ; Schasfoort, F. ; Nienhuis, A. - \ 2015
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2652) - 121
    ecosysteemdiensten - rivieren - hoogwaterbeheersing - waal - regionale planning - betuwe - ecosystem services - rivers - flood control - river waal - regional planning - betuwe
    Doel van dit project is om aan de hand van twee pilots te bepalen wat de mogelijke economische en ecologische meerwaarde is van natuur-inclusieve oplossingen voor waterveiligheidsopgaven uit het Deltaprogramma en wat de meerwaarde van de TEEB-aanpak is in het planvormings- en besluitvormingsproces over deze maatregelen. Dit rapport handelt over de pilot “hoogwatergeul Varik-Heesselt”. De pilot was gericht op toepassing en evaluatie van de TEEB-methode. Het project is in nauw contact met de projectleider van de provincie Gelderland van het lopende planproces uitgevoerd.
    Macroinvertebrate survival during cessation of flow and streambed drying in a lowland stream
    Verdonschot, R.C.M. ; Oosten-Siedlecka, A.M. van; Braak, C.J.F. ter; Verdonschot, P.F.M. - \ 2015
    Freshwater Biology 60 (2015)2. - ISSN 0046-5070 - p. 282 - 296.
    invertebrate communities - prairie stream - desert stream - drought - intermittent - assemblages - responses - rivers - recolonization - resilience
    1.The number of perennial low-order lowland streams likely to experience intermittent flow is predicted to increase in north-western Europe. To understand the effects of such a change on macroinvertebrates, a field experiment was carried out in a currently perennial sandy lowland stream. 2.Using a before–after control–impact design, the flow regime was manipulated to yield two distinct treatments: stagnation (although with little water loss) and drying of the stream (although artificial remnant pools remained in the bed). There was also an unmanipulated control reach. The two treatments were applied simultaneously in separate, consecutive reaches, resulting in 29 days of stagnation and 25 days of streambed drying with surface water only present in the remnant pools. Changes in macroinvertebrate richness, abundance and community composition were recorded, and we assessed whether these changes could be explained by ecological preferences for flow of the various taxa. 3.Stagnation resulted in only minor changes in community composition. A small number of rheophilic taxa disappeared, while taxa preferring standing waters complemented those already present, increasing total biodiversity. In remnant pools in the otherwise dry reach, richness and abundance peaked after they became isolated, indicating a concentration of invertebrates. A subsequent steep decline in richness coincided with hypoxia and increasing conductivity. Culex pipiens/torrentium colonised the pools and was then dominant. Only a small subset of the assemblage successfully used the dry streambed as a refuge. 4.The effect of a shift from perennial to intermittent flow evidently depends on the degree of habitat change. Environmental conditions after cessation of flow are crucial in determining lowland stream macroinvertebrate persistence during water drawdown.
    Dynamics in organic matter processing, ecosystem metabolism and trophic sources for consumers in the Mara River, Kenya
    Masese, F.O. - \ 2015
    Wageningen University. Promotor(en): K.A. Irvine, co-promotor(en): M.E. McClain; G.M. Gettel. - Leiden : CRC Press/Balkema - ISBN 9781138028159 - 195
    organische stof - ecosystemen - landgebruik - ecosysteemdiensten - rivieren - meren - koolstof - stikstof - visserij - aquatische ecologie - organic matter - ecosystems - land use - ecosystem services - rivers - lakes - carbon - nitrogen - fisheries - aquatic ecology

    To properly conserve, restore and manage riverine ecosystems and the services they provide, it is pertinent to understand their functional dynamics. However, there is still a major knowledge gap concerning the functioning of tropical rivers in terms of energy sources supporting riverine fisheries. I reviewed the anthropogenic influences on organic matter processes, energy sources and attributes of riverine food webs in the Lake Victoria basin, but also expanded the review to incorporate recent research findings from the tropics. Contrasting findings have been presented on the diversity of shredders and their role in organic matter processing in tropical streams. Recent tropical research has also highlighted the importance of autochthonous carbon, even in small forested streams. However similar studies are very limited in Afrotropical streams making it difficult to determine their place in emerging patterns of carbon flow in the tropics.

    This study was conducted in the Mara River, which is an important transboundary river with its headwaters in the Mau Forest Complex in Kenya and draining to Lake Victoria through Tanzania. In its headwaters, the basin is drained by two main tributaries, the Amala and Nyangores Rivers which merge in the middle reaches to form the Mara River mainstem. The overall objective of this dissertation was to better understand the functioning of the Mara River by assessing the spatio-temporal dynamics of organic matter sources and supply under different land-use and flow conditions and the influence of these dynamics on energy flow for consumers in the river. I collected benthic macroinvertebrates from open- and closed-canopy streams and classified them into functional feeding groups (FFGs) using gut content analysis. In total, I identified 43 predators, 26 collectors, 19 scrapers and 19 shredders. Species richness was higher in closed-canopy forested streams where shredders were also the dominant group in terms of biomass. Seven shredder taxa occurred only in closed-canopy forested streams highlighting the importance of maintaining water and habitat quality, including the input of leaf litter of the right quality, in the studied streams. The findings suggest that Kenyan highland streams harbor a diverse shredder assemblage contrary to earlier findings that had identified a limited number of shredder taxa.

    I subsequently used the composition of invertebrate functional feeding groups (FFGs) and the ecosystem process of leaf breakdown as structural and functional indicators, respectively, of ecosystem health in upland Kenyan streams. Coarse- and fine-mesh litterbags were used to

    compare microbial (fine-mesh) with shredder + microbial (coarse-mesh) breakdown rates, and by extension, determine the role of shredders in litter processing of leaves of different tree species (native Croton macrostachyus and Syzygium cordatum and the exotic Eucalyptus globulus). Breakdown rates were generally higher in coarse- compared with fine-mesh litterbags for the native leaf species and the relative differences in breakdown rates among leaf species remained unaltered in both agriculture and forest streams. Shredders were relatively more important in forest compared with agriculture streams where microbial breakdown was more important. Moreover, shredder mediated leaf litter breakdown was dependent on leaf species, and was highest for C. macrostachyus and lowest for E. globulus, suggesting that replacement of indigenous riparian vegetation with poorer quality Eucalyptus species along streams has the potential to reduce nutrient cycling in streams.

    To study organic matter dynamics is these streams, I assessed the influence of land use change on the composition and concentration of dissolved organic matter (DOM) and investigated its links with whole-stream ecosystem metabolism. Optical properties of DOM indicated notable shifts in composition along a land use gradient. Forest streams were associated with higher molecular weight and terrestrially derived DOM whereas agriculture streams were associated with autochthonously produced and low molecular weight DOM and photodegradation due to the open canopy. However, aromaticity was high at all sites irrespective of catchment land use. In agricultural areas high aromaticity likely originated from farmlands where soils are mobilized during tillage and carried into streams and rivers by runoff. Gross primary production (GPP) and ecosystem respiration (ER) were generally higher in agriculture streams, because of slightly open canopy and higher nutrient concentrations. The findings of this study are important because, in addition to reinforcing the role of tropical streams and rivers in the global carbon cycle, they highlight the consequences of land use change on ecosystem functioning in a region where land use activities are poised to intensify in response to human population growth.

    Lastly, I used natural abundances of stable carbon (δ13C) and nitrogen (δ15N) isotopes to quantify spatial and temporal patterns of carbon flow in food webs in the longitudinal gradient of the Mara River. River reaches were selected that were under different levels of human and mammalian herbivore (livestock and wildlife) influences. Potential primary producers (terrestrial C3 and C4 producers and periphyton) and consumers (invertebrates and fish) were collected

    during the dry and wet seasons to represent a range of contrasting flow conditions. I used Stable Isotope Analysis in R (SIAR) Bayesian mixing model to partition terrestrial and autochthonous sources of organic carbon supporting consumer trophic groups. Overall periphyton dominated contributions to consumers during the dry season. During the wet season, however, the importance of terrestrially-derived carbon for consumers was higher with the importance of C3 producers declining with distance from the forested upper reaches as the importance of C4 producers increased in river reaches receiving livestock and hippo inputs. This study highlights the importance of large mammalian herbivores on the functioning of riverine ecosystems and the implications of their loss from savanna landscapes that currently harbour remnant populations.

    The results of this dissertation contribute data to discussions on the effects of land use change on the functioning of upland streams and food webs in savanna rivers with regard to carbon flow and the vectoring role played by large mammalian herbivores as they transfer terrestrial organic matter and nutrients into streams and rivers. This study also provides information and recommendations that will guide future research and management actions for the sustainability of the Mara River and linked ecosystems in the Lake Victoria basin.

    Future trends in urbanization and coastal water pollution in the Bay of Bengal: the lived experience
    Zinia, N.J. ; Kroeze, C. - \ 2015
    Environment, Development and Sustainability 17 (2015)3. - ISSN 1387-585X - p. 531 - 546.
    nutrient export - rivers - perspectives - management - phosphorus - nitrogen
    The Bay of Bengal includes coastal seas of several countries, including Bangladesh, India, and Myanmar. We present scenarios for future river export of eutrophying nutrients into the Bay of Bengal, and the role of urbanization therein. We used NEWS (Nutrient Export from WaterSheds) model to analyze trends over the period 1970–2050. The scenarios are based on the Millennium Ecosystem Assessment and indicate the number of people living in urban areas may increase from 22 % in 1970 to about 50 % in 2050. We show that this may considerably increase nutrient levels in rivers from sewage and other sources. For 2050, we calculate that harmful algal blooms may be a potential problem in coastal waters of about 95 % of the total drainage basin of the Bay of Bengal. In addition, we analyze Bangladeshi citizens’ expectations of future trends and how citizens with different worldviews would experience environmental changes (i.e., their lived experience). The citizens indicate that trends as envisaged in our scenarios may be a negative experience. However, some people may experience the trends as positive, because they expected worse.
    Coastal eutrophication in Europe caused by production of energy crops
    Wijnen, J. van; Ivens, W.P.M.F. ; Kroeze, C. ; Löhr, A.J. - \ 2015
    Science of the Total Environment 511 (2015). - ISSN 0048-9697 - p. 101 - 111.
    biomass production - marine ecosystems - future-trends - biofuels - land - rivers - export - agriculture - nitrogen - waters
    In Europe, the use of biodiesel may increase rapidly in the coming decades as a result of policies aiming to increase the use of renewable fuels. Therefore, the production of biofuels from energy crops is expected to increase as well as the use of fertilisers to grow these crops. Since fertilisers are an important cause of eutrophication, the use of biodiesel may have an effect on the water quality in rivers and coastal seas. In this study we explored the possible effects of increased biodiesel use on coastal eutrophication in European seas in the year 2050. To this end, we defined a number of illustrative scenarios in which the biodiesel production increases to about 10–30% of the current diesel use. The scenarios differ with respect to the assumptions on where the energy crops are cultivated: either on land that is currently used for agriculture, or on land used for other purposes. We analysed these scenarios with the Global NEWS (Nutrient Export from WaterSheds) model. We used an existing Millennium Ecosystem Assessment Scenario for 2050, Global Orchestration (GO2050), as a baseline. In this baseline scenario the amount of nitrogen (N) and phosphorus (P) exported by European rivers to coastal seas decreases between 2000 and 2050 as a result of environmental and agricultural policies. In our scenarios with increased biodiesel production the river export of N and P increases between 2000 and 2050, indicating that energy crop production may more than counterbalance this decrease. Largest increases in nutrient export were calculated for the Mediterranean Sea and the Black Sea. Differences in nutrient export among river basins are large.
    Toestand vis en visserij in de zoete Rijkswateren: 2013. Data
    Boois, I.J. de; Graaf, M. de; Griffioen, A.B. ; Keeken, O.A. van; Kuijs, E. ; Os-Koomen, B. van; Westerink, H.J. ; Wiegerinck, Hanz ; Overzee, H.M.J. van - \ 2014
    IJmuiden : IMARES Wageningen UR (Rapport / IMARES Wageningen UR C164a/14) - 468
    zoet water - aquatische ecologie - vissen - monitoring - ijsselmeer - randmeren - rivieren - inventarisaties - fresh water - aquatic ecology - fishes - monitoring - lake ijssel - randmeren - rivers - inventories
    De monitoringen in de zoete Rijkswateren zijn opgezet ten behoeve van het monitoren van de visstand en worden tegenwoordig ook uitgevoerd om de ecologische toestand van de zoete Rijkswateren in kaart te kunnen brengen.
    Multifunctionality of floodplain landscapes: relating management options to ecosystem services
    Schindler, S. ; Sebesvari, Z. ; Damm, C. ; Sluis, T. van der - \ 2014
    Landscape Ecology 29 (2014)2. - ISSN 0921-2973 - p. 229 - 244.
    biodiversity conservation - restoration - indicators - ecology - scales - assessments - knowledge - policy - rivers - reach
    The concept of green infrastructure has been recently taken up by the European Commission for ensuring the provision of ecosystem services (ESS). It aims at the supply of multiple ESS in a given landscape, however, the effects of a full suite of management options on multiple ESS and landscape multifunctionality have rarely been assessed. In this paper we use European floodplain landscapes as example to develop an expert based qualitative conceptual model for the assessment of impacts of landscape scale interventions on multifunctionality. European floodplain landscapes are particularly useful for such approach as they originally provided a high variety and quantity of ESS that has declined due to the strong human impact these landscapes have experienced. We provide an overview of the effects of floodplain management options on landscape multifunctionality by assessing the effects of 38 floodplain management interventions on 21 relevant ESS, as well as on overall ESS supply. We found that restoration and rehabilitation consistently increased the multifunctionality of the landscape by enhancing supply of provisioning, regulation/maintenance, and cultural services. In contrast, conventional technical regulation measures and interventions related to extraction, infrastructure and intensive land use cause decrease in multifunctionality and negative effects for the supply of all three aspects of ESS. The overview of the effects of interventions shall provide guidance for decision makers at multiple governance levels. The presented conceptual model could be effectively applied for other landscapes that have potential for a supply of a high diversity of ESS.
    Toestand vis en visserij in de zoete Rijkswateren. Deel II: Methoden
    Sluis, M.T. van der; Overzee, H.M.J. van; Tien, N.S.H. ; Graaf, M. de; Griffioen, A.B. ; Keeken, O.A. van; Os-Koomen, E. van; Rippen, A.D. ; Wiegerinck, J.A.M. ; Wolfshaar, K.E. van de - \ 2014
    IJmuiden : IMARES (Rapport / IMARES Wageningen UR C175/14) - 83
    zoet water - aquatische ecologie - vissen - monitoring - ijsselmeer - randmeren - rivieren - inventarisaties - fresh water - aquatic ecology - fishes - monitoring - lake ijssel - randmeren - rivers - inventories
    Sinds 2013 worden al deze monitoringprogramma’s jaarlijks in één rapportage gebundeld. Dit rapport bevat de gebruikte methodieken van de verschillende vis-monitoringsprogramma’s in de zoete Rijkswateren
    Rivers running deep : complex flow and morphology in the Mahakam River, Indonesia
    Vermeulen, B. - \ 2014
    Wageningen University. Promotor(en): Remko Uijlenhoet, co-promotor(en): Ton Hoitink. - Wageningen : Wageningen University - ISBN 9789462572065 - 150
    rivieren - morfologie - waterstroming - hydrologie - indonesië - rivers - morphology - water flow - hydrology - indonesia

    Rivers in tropical regions often challenge our geomorphological understanding of fluvial systems. Hairpin bends, natural scours, bifurcate meander bends, tie channels and embayments in the river bank are a few examples of features ubiquitous in tropical rivers. Existing observation techniques fall short to grasp the complex governing processes of flow and morphology. In this thesis new observational techniques are introduced and applied to study the Mahakam River, East Kalimantan, Indonesia. The observations reveal a new type of morphological regime, characterized by non-harmonic meanders, scour and strong variation of the cross-sectional area. The anomalous geometry induces a complex three-dimensional flow pattern causing longitudinal flow to be concentrated near the bed of the river.

    In Chapter 2 a wavelet based technique is introduced to characterize meander shape in a quantitative, objective manner. A scale space forest composed of a set of rooted trees represents the meandering planform. Based on the rooted trees, the locally dominant meander wavelengths are defined along the river. Sub-meander scale spectral density in the wavelet transform is used to determine a set of metrics quantifying bend skewness and fattening. Negative fattening parameterizes the so-called non-harmonic or hairpin bend character of meanders. The super-meander scale tree represents the embedding of meanders into larger-scale fluctuations, spanning from double-headed meander scales until the scale of the valley thalweg. The new approach is used to quantify the anomalous planform geometry of the Mahakam River in a comparison with the Red River and the Purus River.

    The geometry of the Mahakam River is analyzed into more detail in Chapter 3, where the highly curved non-harmonic meanders are related to deep scours in the river bed. A total of 35 scours is identified which exceed three times the average river depth, and four scours exceed the river depth over four times. The maximum scour depth strongly correlates with channel curvature and systematically occurs half a river width upstream of the bend apex. Most scours occur in a freely meandering zone of the river. A systematic reconnaissance of the river banks reveals a switch of erosion-deposition patterns at high curvature. Advancing banks normally observed at the inner side of a bend are mostly found at the outer side of high-curvature reaches, while eroding banks switch from the outer side for mildly curved bends to the inner side for bends with high curvature. The overall lateral migration rate of the river is low. These results indicate a switch of morphological regime at high curvatures, which requires detailed flow measurements to unravel the underlying physical processes.

    Taking flow measurements in the deep scours of the Mahakam River presents a challenge to contemporary methods in hydrography. Acoustic Doppler Current Profilers (ADCPs) are capable of profiling flow velocity over large distances from a research vessel, but the existent data processing techniques assume homogeneity of the flow between the divergent acoustic beams. This assumption fails for complex three dimensional flows as found in the scours. In Chapter 4 a new ADCP data processing technique is developed that strongly reduces the extent over which the flow needs to be assumed homogeneous. The new method is applied to flow measurements collected in a river bend with a scour exceeding 40 m depth. Results based on the new approach reveal secondary flow patterns which remain invisible adopting the conventional method.

    Chapter 5 aims to better understand flow in sharp bends, by combining analyses of the flow measurements from a deep scour with Large Eddy Simulations of the flow. The three-dimensional flow field is strongly dominated by horizontal circulations at both sides of the scour. The dramatic increase in cross-sectional area (from 2200 m2 to 7000 m2 ) plays a crucial role in the generation of the two horizontal recirculation cells. An existing formulation to predict water surface gradients in bends is extended to include the effect of cross-sectional area variations, next to the effect of curvature changes. Variation in the cross-sectional area develops adverse water surface gradients explaining the flow recirculation. The depth increase toward the scour causes a strong downward flow (up to 12 cm s − 1 ) creating a non-hydrostatic pressure distribution, steering the core of the flow toward the bed. The latter aspect is poorly reproduced by the Large Eddy Simulations, which may relate to the representation of turbulent shear stresses.

    In Chapter 6 a novel technique is introduced to better monitor turbulence properties in complex river flows from ADCP measurements, exploiting what is discarded in observations of the mean flow. It extends the so-called variance method, using two ADCPs instead of one. The availability of eight acoustic beams, four from each ADCP, changes an otherwise unsolvable set of equations with six unknowns into an overdetermined system of eight equations with six unknowns. This allows to solve for the complete Reynolds stress tensor, yielding profiles of Reynolds stresses over almost the entire water column. Widely applied assumptions on turbulence anisotropy ratios are shown to be incorrect, which reveals a knowledge gap in open channel turbulence.

    Chapter 7 uses the technique developed in Chapter 6 to investigate the degree in which bed shear stress can be monitored continuously from an ADCP mounted horizontally at the river bank (HADCP). A calibrated boundary layer model is applied to estimate time-series of cross-river bed-shear stress profiles from HADCP velocity measurements. It is concluded the HADCP measurement can represent the regional bed shear stresses, as inferred from a logarithmic velocity profile, reasonably well. These regional bed-shear stresses, in turn, poorly represent the local estimates obtained from coupled ADCP measurements, which are more directly related to processes of sediment transport and complex river morphology. Detailed observations of turbulence properties may be the key to improve our understanding of complex river flow and morphology.

    Robust, multifunctional flood defenses in the Dutch rural riverine area
    Loon-Steensma, J.M. van; Vellinga, P. - \ 2014
    Natural Hazards and Earth System Sciences 14 (2014). - ISSN 1561-8633 - p. 1085 - 1098.
    dijken - versterking - rivieren - platteland - hoogwaterbeheersing - gebiedsgericht beleid - nederland - dykes - reinforcement - rivers - rural areas - flood control - integrated spatial planning policy - netherlands - risk-management
    This paper reviews the possible functions as well as strengths, weaknesses, opportunities, and threats for robust flood defenses in the rural riverine areas of the Netherlands on the basis of the recent literature and case studies at five locations in the Netherlands where dike reinforcement is planned. For each of the case studies semi-structured interviews with experts and stakeholders were conducted. At each of the five locations, suitable robust flood defenses could be identified that would contribute to the envisaged functions and ambitions for the respective areas. Primary strengths of a robust, multifunctional dike in comparison to a traditional dike appeared to be the more efficient space use due to the combination of different functions, a longer-term focus and greater safety.
    Human impacts on tides overwhelm the effect of sea level rise on extreme water levels in the Rhine–Meuse delta
    Vellinga, N.E. ; Hoitink, A.J.F. ; Vegt, M. van der; Zhang, W. ; Hoekstra, P. - \ 2014
    Coastal Engineering 90 (2014). - ISSN 0378-3839 - p. 40 - 50.
    rivieren - waterstand - getijden - zeespiegelschommelingen - delta's - menselijke activiteit - inventarisaties - rivers - water level - tides - sea level fluctuations - deltas - human activity - inventories - river flow - netherlands - variability - subsidence - division - china
    With the aim to link tidal and subtidal water level changes to human interventions, 70 years of water level data for the Rhine–Meuse tidal river network is analysed using a variety of statistical methods. Using a novel parameterization of probability density functions, mean high and low water levels are examined, and extreme water levels are investigated by applying the combined Mann–Kendall and Pettitt tests to find trends and trend changes. Tidal water levels are studied based on harmonic analysis. Results show that the mean water levels throughout the system rise with the same pace as the mean sea level. However, high- and low water levels do not show the same increase, and the spatial variability in decadal trends in high- and low water levels is high. High water and low water extremes generally decrease. Both the extreme water level analysis and the harmonic analysis display significant trend breaks in 1970, 1981 and 1997. These breaks can be attributed to the closure of the Haringvliet estuary, the removal of sluices and the removal of a dam, respectively, which radically alter the tidal motion. These results demonstrate that the direct human influence on the tidal motion can overwhelm the effect of mean sea level rise on water level extremes.
    Ex situ treatment of sediments with granular activated carbon : a novel remediation technology
    Rakowska, M.I. - \ 2014
    Wageningen University. Promotor(en): Huub Rijnaarts, co-promotor(en): Bart Koelmans; Tim Grotenhuis. - Wageningen : Wageningen University - ISBN 9789461738981 - 240
    polycyclische aromatische koolwaterstoffen - polychloorbifenylen - gechloreerde koolwaterstofpesticiden - verontreinigde sedimenten - remediatie - actieve kool - mariene sedimenten - rivieren - polycyclic aromatic hydrocarbons - polychlorinated biphenyls - organochlorine pesticides - contaminated sediments - remediation - activated carbon - marine sediments - rivers

    Over the last decades, industrial and urban development and emisions of many hazardous organic compounds have threatened the ecological quality of marine and freshwater sediments. Sediments accumulate hydrophobic organic compounds (HOCs) such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and thus may pose serious risks to ecosystems and human health. Over the past years sediment treatment by sorbent addition such as activated carbon (AC) to achieve sequestration of HOCs in situ has been proposed as an alternative approach to traditional remediation technologies such as dredging and disposal. The present research was meant to explore ex situ extraction of sediment by granular AC (GAC) (‘active stripping’) as a novel approach in comparison to traditional in situ AC sediment remediation technologies using amendments of powdered AC (PAC) or GAC.

    Chapter2 discusses the current state of the art in AC amendment technology as a method for sediment remediation. In this chapter, major knowledge gaps are revealed on sediment-AC-HOC interactions controlling the effectiveness of HOC binding such as AC type, particle size, dosage, sediment and sorbate characteristics,and efficiency of AC to reduce bioaccumulation in benthic invertebrates.In addition, the review discusses potential negative effects of AC on aquatic life. Finally, we discuss whether the effects of AC addition can be predicted using fate and transport models.

    Chapter 3explores the potential of GAC in the context of ex situ sediment remediation technology. Since the added GAC would compete for the sorption of HOCs with natural sediment phases, its effectiveness would strongly depend on its dosage. Consequently, in this chapter we investigate the distribution coefficients for short-term sorption processes, and the optimal dosage level of GAC to be used in intensive sediment remediation. A suite of candidate GAC materials is screened for maximum efficiency in extracting PAHs from sediment with very high PAH and oil pollution levels within 24 h. The effectiveness of GAC is compared to a single-step solid phase extraction (SPE) with Tenax beads, Sorption data are interpreted in terms of aqueous phase concentration reduction ratios and distribution coefficients. Despite the considerable fouling of GAC by organic matter and oil, 50-90% of the most available PAH was extracted by the GAC during 28-d contact time, at a dose as low as 4%.

    A prerequisite for the application of active stripping with GAC in contaminatedsediment remediation is effective transport of pollutantsfrom the sediment to the GAC during the relatively short mixing stage. Therefore, in Chapter 4kinetics of PAH transfer from sediment using GAC at a relatively low dose as a solid extraction phase kinetic parameters are obtained by modeling experimental sediment-GAC exchange kinetic data following a two-stage model calibration approach. Rate constants (kGAC) for PAH uptake by GAC range from 0.44 to 0.0005 d-1, whereas GAC sorption coefficients (KGAC) range from 105.57to 108.57L kg-1. These results show that ex situ extraction with GAC is sufficiently fast and effective to reduce the risks of the most available PAHs among those studied, such as fluorene, phenanthrene and anthracene.

    It is unclear how the GAC/sediment mixing step affects desorption kinetics of HOCs for instance by changing the sediment particle size distributions, and whether these factors may influence the effectiveness of ex situ GAC extraction technology. Chapter 5 presents the results of investigations on the effect of mixing intensity on the extraction rate of PAHs from contaminated sediment. Desorption data are interpreted using a radial diffusion model. Mixing caused the 161 µm particles originally present at a stirring rate of 200 rpm to decrease in size to 9 µm at a rate of 600 rpm. Desorption rate constants decreased with increasing PAH hydrophobicity but increased with the intensity of mixing. The results demonstrate that desorption of PAHs is significantly accelerated by a reduction of particle aggregate size caused by shear forces induced by mixing.

    So far, the remediation effectiveness and ecological side effects of AC application have been studied in the short term, and mainly in laboratory studies. However, it is still not clear to what extent these reduced pore water concentrations change over longer times and how they differ for chemicals and for different AC remediation scenarios under field conditions. Chapter 6 presents (pseudo-)equilibrium as well as kinetic parameters for in situ sorption of a series of PAHs and PCBs to powdered and granular activated carbons (AC) after three different sediment treatments: sediment mixed with powdered AC (PAC), sediment mixed with granular AC (GAC), and addition of GAC followed by 2 d mixing and subsequent removal (‘sediment stripping’) in the field. Remediation efficiency is assessed by quantifying fluxes towards SPME passive samplers inserted in the sediment top layer, which shows that efficiency decrease in the order of PAC > GAC stripping > GAC addition. Sorption was very strong to PAC, with log KAC (L/kg) values up to 10.5. Log KAC values for GAC ranged from 6.3 - 7.1 and 4.8 - 6.2 for PAHs and PCBs, respectively. Log KAC values for GAC in the stripped sediment were 7.4 - 8.6 and 5.8 - 7.7 for PAH and PCB. Apparent first order adsorption rate constants for GAC (kGAC) in the stripping scenario were calculated with a first-order kinetic model and ranged from 1.6×10-2 (PHE) to 1.7×10-5 d-1 (InP). This study showed that sediment treatment with PAC is most effective and less prone to organic matter fouling and ongoing natural processes in the field. The effectiveness of GAC is higher in the 48 h sediment stripping scenario than in the GAC amendment approach.

    In Chapter 7 the effects of three different AC treatments (see above) on HOC concentrations in pore water, benthic invertebrates, zooplankton and fish (Leuciscus idus melanotus) are tested. The AC treatments result in a significant decrease in HOC concentrations in pore water, benthic invertebrates, zooplankton, macrophytes and fish. In 6 months, PAC treatment caused a reduction of accumulation of PCBs in fish by a factor of 20 bringing pollutant levels below toxic thresholds. All AC treatments supported growth of fish, but growth was inhibited in the PAC treatment, which is likely to be explained from reduced nutrient concentrations, resulting in lower zooplankton (i.e., food) densities for the fish. During the course of the field study, sediment stripping as well as sediment treatment with GAC turned out to be slower in reducing PCB bioaccumulation in biota, but the treatments were not harmful to any of the biota either.

    In the final chapter (Chapter 8), overarching answers to the main research questions (see above) are formulated and an outlook regarding the actual use of ex situ GAC is provided.

    Toestand vis en visserij in de zoete Rijkswateren. Deel III: Data
    Boois, I.J. de; Overzee, H.M.J. van; Graaf, M. de; Keeken, O.A. van; Kuijs, E.K.M. ; Os-Koomen, E. van; Westerink, H.J. ; Wiegerinck, J.A.M. - \ 2014
    IJmuiden : IMARES (Rapport / IMARES Wageningen UR C060/13) - 399
    zoet water - aquatische ecologie - vissen - monitoring - ijsselmeer - randmeren - rivieren - inventarisaties - fresh water - aquatic ecology - fishes - monitoring - lake ijssel - randmeren - rivers - inventories
    Het rapport “Toestand Vis en Visserij in de Zoete Rijkswateren” bestaat uit drie delen. Dit rapport bevat de resultaten van de vismonitoringen in de zoete Rijkswateren. Het omvat de volgende bemonsteringen: - Open water monitoring IJssel- en Markermeer - Oeverbemonstering IJssel- en Markermeer - Bemonstering zeldzame vis IJssel- en Markermeer - Bemonstering diadrome vis Kornwerderzand - Actieve monitoring grote rivieren en delta - Passieve monitoring grote rivieren en delta - Zalmsteekmonitoring grote rivieren De monitoringen in en rond het IJssel- en Markermeer worden gefinancierd door het ministerie van EZ, de monitoringen op de rivieren door Rijkswaterstaat.
    Toestand vis en visserij in de Zoete Rijkswateren: 2012 Deel I: Trends van de visbestanden, vangsten en ecologische kwaliteit ratio's
    Graaf, M. de; Overzee, H.M.J. van; Boois, I.J. de; Vries, P. de; Tien, N.S.H. ; Tulp, I. ; Griffioen, A.B. - \ 2014
    IJmuiden : IMARES (Rapport / IMARES Wageningen UR C058/13) - 52
    zoet water - aquatische ecologie - vissen - monitoring - ijsselmeer - randmeren - rivieren - inventarisaties - fresh water - aquatic ecology - fishes - monitoring - lake ijssel - randmeren - rivers - inventories
    De visstand bemonsteringen die in opdracht van RWS Waterdienst plaatsvinden maken deel uit van een uitgebreider programma: de Monitoring van de Waterstaatkundige Toestand des Lands (MWTL). In de loop der tijd is uit pragmatische overwegingen de uitvoering en financiering van de visstand bemonsteringen verdeeld over RWS en Min EZ, waarbij grofweg RWS de vismonitoring in de rivieren en delta uitvoert en Min EZ de vismonitoring in het IJsselmeer en Markermeer
    Bouwstenen voor de grensoverschrijdende Vecht : een half-natuurlijke laaglandrivier tussen Emlichheim en Hardenberg
    Maas, G.J. ; Woestenburg, M. - \ 2014
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2491) - 22
    rivieren - natuurontwikkeling - kaderrichtlijn water - waterbeheer - hoogwaterbeheersing - ecologisch herstel - overijssel - duitsland - grensgebieden - rivers - nature development - water framework directive - water management - flood control - ecological restoration - overijssel - germany - frontier areas
    De Duits-Nederlandse rivier de Vecht wordt over de volle lengte weer zoveel mogelijk teruggebracht in een natuurlijke staat. In de studie naar de Vecht tussen Emlichheim en Hardenberg is onderzocht wat de effecten zijn van de verschillende bouwstenen op de rivier, en ook welke gevolgen de maatregelen hebben voor de randvoorwaarden die gesteld zijn. Om de Vecht om te vormen tot een half-natuurlijke rivier is een integrale aanpak nodig. Herstel van de Vecht vraagt om ingrijpende maatregelen.
    Bausteine für die grenzüberschreitende Vechte : ein lebendigen Flachlandfluss zwischen Emlichheim und Hardenberg
    Maas, G.J. ; Woestenburg, M. - \ 2014
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2492) - 22
    rivieren - natuurontwikkeling - kaderrichtlijn water - waterbeheer - hoogwaterbeheersing - ecologisch herstel - grensgebieden - duitsland - overijssel - rivers - nature development - water framework directive - water management - flood control - ecological restoration - frontier areas - germany - overijssel
    De Duits-Nederlandse rivier de Vecht wordt over de volle lengte weer zoveel mogelijk teruggebracht in een natuurlijke staat. In de studie naar de Vecht tussen Emlichheim en Hardenberg is onderzocht wat de effecten zijn van de verschillende bouwstenen op de rivier, en ook welke gevolgen de maatregelen hebben voor de randvoorwaarden die gesteld zijn. Om de Vecht om te vormen tot een half-natuurlijke rivier is een integrale aanpak nodig. Herstel van de Vecht vraagt om ingrijpende maatregelen.
    Toestand vis en visserij in de zoete Rijkswateren. Deel II: Methoden
    Overzee, H.M.J. van; Boois, I.J. de; Graaf, M. de; Goudswaard, P.C. ; Keeken, O.A. van; Kuijs, E.K.M. ; Lohman, M. ; Os-Koomen, E. van; Westerink, H.J. ; Wiegerinck, J.A.M. - \ 2013
    IJmuiden : IMARES (Rapport / IMARES Wageningen UR C059/13) - 48
    zoet water - aquatische ecologie - vissen - monitoring - ijsselmeer - randmeren - rivieren - inventarisaties - fresh water - aquatic ecology - fishes - monitoring - lake ijssel - randmeren - rivers - inventories
    Het rapport “Toestand Vis en Visserij in de Zoete Rijkswateren” bestaat uit drie delen. Dit rapport (Deel II) is een achtergronddocument waarin de gebruikte monitoringsmethodieken in de verschillende vismonitoringen in de zoete Rijkswateren in detail worden beschreven. Het omvat de volgende bemonsteringen: - Open water monitoring IJssel- en Markermeer - Oeverbemonstering IJssel- en Markermeer - Bemonstering zeldzame vis IJssel- en Markermeer - Overige gegevens van vis in het IJssel-en Markermeer - Bemonstering diadrome vis Kornwerderzand - Actieve monitoring grote rivieren en delta - Passieve monitoring grote rivieren en delta - Zalmsteekmonitoring grote rivieren.
    Field experiment on alternate bar development in a straight sand-bed stream
    Eekhout, J.P.C. ; Hoitink, A.J.F. ; Mosselman, E. - \ 2013
    Water Resources Research 49 (2013). - ISSN 0043-1397 - p. 8357 - 8369.
    sediment - channels - instability - patterns - meanders - growth - rivers
    Alternate bars in rivers and streams develop as a result of differences in length scales involved in the adjustment of flow and sediment transport to irregularities of the bed. The amount of field evidence supporting theoretical insights is highly limited. Here, we present results from a large-scale field experiment in a 600 m long straight reach. Over a period of almost 3 years, the channel was allowed to evolve autogenously from initially flat bed conditions, subject to discharge variation. Alternate bars developed within 8 months from the start of the experiment. The initial stages of bar development included bar growth, both in wavelength and amplitude, and bar migration. The latter was too limited to classify the bars as being migrating bars; therefore, we classify the bars as nonmigrating bars. Toward the end of the experiment, the regular alternate bar pattern evolved into an irregular pattern and bar amplitude started to decrease. From the start of the experiment we observed a declining channel slope, from 1.8 m km-1 initially to 0.9 m km-1 halfway the experiment, after which it stabilized. We applied two bar theories to establish their predictive capacity. Both bar theories predicted the development of alternate bars under the constructed channel conditions. In response to the declining channel slope, both theories predicted a decreasing likelihood for the development of alternate bars. Our study shows that under field conditions, the applied bar theories may predict the initial stages of bed development.
    Overijsselse Vecht : Meer ambitie gevraagd
    Willems, D. ; Corporaal, A. - \ 2013
    Het Waterschap 9 (2013). - ISSN 1380-4251 - p. 29 - 29.
    rivieren - stroomgebieden - gereguleerde rivieren - herstelbeheer - deregulering - opinies - waterschappen - overijssel - rivers - watersheds - regulated rivers - restoration management - deregulation - opinions - polder boards
    De grensoverschrijdende Vecht heeft klasse. In potentie althans. Momenteel ligt ze er geknot bij: gestuwd en rechtgetrokken - een verstoord, kwetsbaar watersysteem. Hulp is onderweg: het breedgedragen programma Ruimte voor de Vecht beoogt meer veiligheid en meer recreatie in een meer natuurlijke (halfnatuurlijke) laaglandrivier. Maar is dit genoeg? De auteurs pleiten voor meer ambitie.
    The links between global carbon, water and nutrient cycles in an urbanizing world — the case of coastal eutrophication
    Kroeze, C. ; Hofstra, N. ; Ivens, W. ; Löhr, A. ; Strokal, M. ; Wijnen, J. van - \ 2013
    Current Opinion in Environmental Sustainability 5 (2013)6. - ISSN 1877-3435 - p. 566 - 572.
    climate-change - surface-water - reactive nitrogen - rivers - boundaries - planetary - impacts - system - land - consequences
    The natural cycles of carbon (C), nitrogen (N), phosphorus (P) and water have been disturbed substantially by human activities. Urbanizing coastal drainage basins and large river deltas are located at the interface of freshwater and coastal components of the larger earth system and the process of urbanization is increasingly affecting these cycles. We take coastal water pollution as an example to illustrate this. To ensure sustainable development of urban-dominated water systems, future research challenges must include studies of the effects of the urbanization process on biogeochemical cycles that firstly, account for feedbacks and tipping points at the global scale; secondly, link to the Sustainability Development Goals; and finally, link to other forms of pollution. Urban coastal systems are of particular interest when exploring human–water–nutrient cycle interactions, and effective solutions for environmental and health problems associated with these interactions.
    Cost-effective solutions for water quality improvement in the Dommel river supported by sewer-WWTP-river integrated modelling
    Benedetti, L. ; Langeveld, J. ; Nieuwenhuijzen, A.F. van; Jonge, J. de; Weijers, S. ; Klein, J.J.M. de; Nopens, I. ; Flameling, T. ; Zanten, O. van - \ 2013
    Water Science and Technology 68 (2013)5. - ISSN 0273-1223 - p. 965 - 973.
    stedelijk afvalwater - afvalwaterbehandeling - oppervlaktewaterkwaliteit - rivieren - aquatische ecologie - controle - infrastructuur - onzekerheidsanalyse - kaderrichtlijn water - noord-brabant - municipal wastewater - waste water treatment - surface water quality - rivers - aquatic ecology - control - infrastructure - uncertainty analysis - water framework directive - noord-brabant - urban drainage systems - real-time control - treatment-plant - simulation - management - pollution
    This project aims at finding cost-efficient sets of measures to meet the Water Framework Directive (WFD) derived goals for the Dommel River (The Netherlands). Within the project, both acute and long-term impacts of the urban wastewater system on the chemical and ecological quality of the river are studied with a monitoring campaign in the urban wastewater system (wastewater treatment plant and sewers) and in the receiving surface water system. An integrated model, which proved to be a powerful tool to analyse the interactions within the integrated urban wastewater system, was first used to evaluate measures in the urban wastewater system using the existing infrastructure and new real-time control strategies. As the latter resulted to be beneficial but not sufficient, this paper investigated the use of additional infrastructural measures to improve the system cost-effectively and have it meet the Directive's goals. Finally, an uncertainty analysis was conducted to investigate the impact of uncertainty in the main model assumptions and model parameters on the performance robustness of the selected set of measures. Apart from some extreme worst-case scenarios, the proposed set of measures turned out to be sufficiently robust. Due to the substantial savings obtained with the results of this project, the pay-back time of the whole monitoring and modelling work proved to be less than 5 months. This illustrates the power of mathematical modelling for decision support in the context of complex urban water systems
    Runoff, discharge and flood occurrence in a poorly gauged tropical basin : the Mahakam River, Kalimantan
    Hidayat, H. - \ 2013
    Wageningen University. Promotor(en): Remko Uijlenhoet, co-promotor(en): Ton Hoitink. - S.l. : s.n. - ISBN 9789461737434 - 114
    oppervlakkige afvoer - afvoer - overstromingen - monitoring - tropen - modellen - rivieren - cartografie - voorspelling - kalimantan - indonesië - runoff - discharge - floods - monitoring - tropics - models - rivers - mapping - prediction - kalimantan - indonesia

    Tidal rivers and lowland wetlands present a transition region where the interests of hydrologists and physical oceanographers overlap. Physical oceanographers tend to simplify river hydrology, by often assuming a constant river discharge when studying estuarine dynamics. Hydrologists, in turn, generally ignore the direct or indirect effects of tides in water level and discharge records. This thesis aims to improve methods to monitor, model and predict discharge dynamics in tidal rivers and lowland wetlands, by focussing on the central and lower reaches of the River Mahakam (East Kalimantan, Indonesia), and the surrounding lakes area. The 980-km long river drains an area of about 77100 km2 between 2°N - 1°S and 113°E - 118°E. Due to its very mild bottom slope, a significant tidal influence occurs in this river. The middle reach of the river is located in a subsiding basin, parts of which are below mean sealevel, featuring peat swamps and about thirty lakes connected to the river via tie channels.

    Upstream of the lakes area, at about 300 km from the river mouth, an acoustic Doppler current profiler (H-ADCP) has been horizontally deployed at a station near the city of Melak (Chapter 2). The H-ADCP profiles of velocity are converted to discharge adopting a new calibration methodology. The obtained time-series of discharge show the tidal signal is clearly visible during low flow conditions. Besides tidal signatures, the discharge series show influences by variable backwater effects from the lakes, tributaries and floodplain ponds. The discharge rate at the station exceeds 3250 m3s-1 with a hysteretic behaviour. For a specific river stage, the discharge range can be as high as 2000 m3s-1. Analysis of alternative types of rating curves shows this is far beyond what can be explained from kinematic wave dynamics. Apart from backwater effects, the large variation of discharge for a specified river stage can be explained by river-tide interaction, impacting discharge variation especially in the fortnightly frequency band.

    A second H-ADCP station has been setup in the lower reach of the Mahakam, near the city of Samarinda, where the tidal discharge amplitude generally exceeds the discharge related to runoff (Chapter 3). Conventional rating curve techniques are inappropriate to model river discharge at this tidally influenced station. As an alternative, an artificial neural network (ANN) model is developed to investigate the degree to which tidal river discharge at Samarinda station can be predicted from an array of level gauge measurements along the tidal river, and from tidal level predictions at sea. The ANN-based model produces a good discharge estimation, as established from a consistent performance during both the training and the validation periods, showing the discharges can be predicted from water levels only, once that a trained model is available. The ANN models perform well in predicting discharges up to two days in advance.

    Chapter 4 addresses the role of backwater effects and tidal influences on discharge time-series used to calibrate a rainfall-runoff model. The HBV rainfall-runoff model is implemented for the Mahakam sub-catchment upstream of Melak (25700 km2). In a first approach, the model is calibrated using a discharge series derived from the H-ADCP measurements from Melak station. In a second approach, discharge estimates derived from a rating curve are used to calibrate the model. Adopting the first approach, a comparatively low model efficiency is obtained, which is attributed to the backwater and tidal effects that are not captured in the model. The second approach produces a relatively higher model efficiency, since the rating curve filters the backwater effects out of the discharge series. Seasonal variation of terms in the water balance is not affected by the choice for one of the two calibration strategies, which shows that backwaters do not have a systematic seasonal effect on the river discharge.

    To allow for investigation of the causes of backwater effects, satellite radar remote sensing is employed to monitor water levels in wetlands (Chapter 5). A series of Phased Array L-band Synthetic Aperture Radar (PALSAR) images is used to observe the dynamics of the Mahakam River floodplain. To analyze radar backscatter behavior for different land cover types, several regions of interest are selected, based on land cover classes. Medium shrub, high shrub, fern/grass, and degraded forest are found to be sensitive to flooding, whereas peat forest, riverine forest and tree plantation backscatter signatures only slightly change with flood inundation. An analysis of the relationship between radar backscatter and water levels is carried out. For lakes and shrub covered peatland, for which the range of water level variation is high, a good water level-backscatter correlation is obtained. In peat forest covered peatland, subject to a small range of water level variation, water level-backscatter correlations are poor, limiting the ability to obtain a floodplain-wide water surface topography from the radar images.

    Chapter 6 continues to investigate the degree in which satellite radar remote sensing can serve to distinguish between dry areas and wetlands, which is a difficult task in densely vegetated areas such as peat domes. Flood extent and flood occurrence information are successfully extracted from a series of radar images of the middle Mahakam lowland area. A fully inundated region is easily recognized from a dark signature on radar images. Open water flood occurrence is mapped using a threshold value taken from radar backscatter of the permanently inundated areas. Radar backscatter intensity analysis of the vegetated floodplain area reveals consistently higher backscatter values, indicating flood inundation under forest canopy. Those observations are used to establish thresholds for flood occurrence mapping in the vegetated area. An all-encompassing flood occurrence map is obtained by combining the flood occurrence maps for areas with and without vegetation.

    Chapter 7 synthesizes the findings from the previous chapters. It is concluded that the backwater effects and subtle tidal influences may prevent the option to predict river discharge using rating curves, which can best be interpreted as a stage-runoff relationship. H-ADCPs offer a promising alternative to monitor river discharge. For a tidal river, an ANN model can be used as a tool for data gap filling in an H-ADCP based discharge series, or even to derive discharge estimates solely from water levels and water level predictions. Discharge can be predicted several time-steps ahead, allowing water managers to take measures based on forecasts. The stage-runoff relationship derived from a continuous series of H-ADCP based discharge estimates may be expected to be much more accurate than a similar rating curve derived from a small number of boat surveys. The flood occurrence map derived from PALSAR images can offer a detailed insight into the hydroperiod, the period in which a soil area is waterlogged, and flood extent of the lowland area, illustrating the added value of radar remote sensing to wetland hydrological studies. In future work, radar-based floodplain observations may serve to calibrate hydrodynamic models simulating the processes of flooding and emptying of the lakes area.

    Multi-scale tectonic controls on fluvial terrace formation in a glacioeustatically-dominated river system: inference from the lower Min¿o terrace record
    Viveen, W. - \ 2013
    Wageningen University. Promotor(en): Tom Veldkamp, co-promotor(en): R.T. van Balen; J.R. Vidal Romani; Jeroen Schoorl. - S.l. : s.n. - ISBN 9789461737281 - 222
    fluvial soils - terrassen - rivierterrasgronden - tektoniek - klimaatverandering - zeespiegelschommelingen - rivieren - rivierdalen - spanje - portugal - fluvial soils - terraces - river terrace soils - tectonics - climatic change - sea level fluctuations - rivers - river valleys - spain - portugal

    The general aim of this thesis is to untangle the interacting effects of climate, glacioeustacy, and regional, and local tectonics on fluvial terrace formation. The NW Iberian lower Miño River valley was chosen as a study site, because for this region, a very detailed, long-term, climate record is available. The lower Miño is situated near the Atlantic Ocean, which ensures that the influence of changing past sea levels was registered in the terrace record. Then, there is controversy about the presence or absence of tectonic activity, although a well-developed network of pre-existing faults and seismic activity in the region suggest that tectonic activity is present. Lastly, a completely preserved terrace sequence makes it possible to study the evolution of the area in detail. These, and more details, are found in Chapter 1.

    In Chapter 2, a regional assessment of recent tectonic activity is made. Studies on faulted terrace deposits and the recognition of small, fault-bounded tectonic basins indicate the presence of neo-tectonic activity. Further evidence is gathered from a tectono-geomorphic analysis, whereby deeply incised valleys, as well as asymmetrically-developed tributary catchments, and the presence of knick points in river profiles that coincide with the presence of structural lineaments, show that the eastern part of the study area experiences tectonic deformation. It is proposed that due to the non-optimal angle between the orientation of the pre-existing faults, and the current horizontal stress orientation, these older faults are re-activated, resulting in strain transfer from one fault segment to another. This results in differential block movements leading to local extension and basin subsidence. Alternatively, strike-slip activity may have caused the tectonic basins, but for this mechanism no evidence was found.

    The focus of Chapter 3 is on a local terrace staircase near the village of Vila Meã. First, the terrace staircase and associated fluvial deposits are described in detail. Then, an age model for the Vila Meã terraces is presented on basis of thermoluminescence and Cosmogenic Ray Exposure (CRE) dating. Minimum ages of up to 650 ka are calculated. On basis of these ages, and terrace surface altitudes, maximum incision rates of 0.07 to 0.09 m ka-1 are reconstructed. It is then discussed that these rates can be used as proxies for regional, vertical tectonic uplift. In the final part of the Chapter, new ideas are presented on the evolution of the lower Miño fluvial terraces. Based on observations made from the terrace deposits, and the proximity of a narrow, steep continental shelf, it is suggested that the fluvial terraces were formed during the initial period of sea level fall, and subsequently incised. Vertical uplift would then have occurred to preserve the terraces above the current river bed.

    In Chapter 4, the focus shifts from a local terrace staircase to the regional terrace record. The entire 55-km long terrace section of the lower Miño is investigated, and 4 selected terrace transects are discussed in terms of number of terraces and sedimentology. Because there is disagreement on the exact number of terraces and their correlations, a new long-distance terrace correlation scheme is presented. The new scheme is based on studies of weathered quartzite gravels in the 4 selected transects. Observed similarities in weathering rate between the transects leads to a proposed terrace correlation gradient of 1 m km-1. The often used correlation model that the terraces tread parallel to the current river bed (gradient 0 m km-1) is then rejected. The second half of the Chapter focuses on a longitudinal profile modelling experiment with the FLUVER 2 model. The evolution of the entire Miño-Sil system is modelled over a time period of 450 ka. The outcomes show that a regional uplift rate of 0.08 m ka-1 in combination with glacioeustatic movements seem to be responsible for terrace formation in the lower Miño valley, and thus confirm the earlier hypotheses in Chapter 3. Climate-induces variations in discharge intensity or timing do not have a dominant effect on terrace formation. The outcomes furthermore indicate that the CRE ages presented in Chapter 3, appear to be very close to exact timing of terrace abandonment.

    The results of the foregoing Chapters are integrated and implemented in Chapter 5, resulting in a new, detailed, fluvial terrace map of the entire 67-km reach of the lower Miño River. Both the Spanish and Portuguese part is incorporated. The map is derived from detailed mapping from a 5-m Digital Elevation Model (DEM) and over 1500 hours of fieldwork. The map shows the regional distribution of 10 terrace levels and one floodplain level, as well as 9 tectonic basins. A layer with fault elements gives a structural tectonic context to the map. Additional layers give information about more than 400 sites with mapped terrace sediment thicknesses and palaeoflow directions. Results from this mapping exercise show the highly fragmented nature of terrace and basin distribution, which is controlled by N-S, E-W and NW-SE trending faults. The map also suggests the presence of unpaired terraces along the river, which may be caused by localised differential movements of tectonic blocks.

    These localised movements are the topic of Chapter 6. Here, the interactions between regional vertical uplift, local basin subsidence, and unequal uplift on both sides of the Miño River on terrace formation are investigated by means of a forward modelling exercise with the TERRACE model. The model simulations that match best with mapped terraces and fluvial sediment thicknesses are the ones that incorporate all three effects of vertical uplift, basin subsidence, and unequal uplift. This shows that terrace preservation is the complex end result of three, interacting, tectonic processes. A regional uplift rate of 0.10 m ka-1 gave the best results, which is slightly higher than the rate of 0.08 m ka-1 presented in Chapter 3. This confirms that regional uplift increases from the coast towards the east, which is in agreement with the findings of Chapter 2. Another important result is that the interacting effect of the three aforementioned tectonic processes can lead to fill terraces one valley side, and strath terraces at the other.

    In Chapter 7, all findings of the previous Chapters are combined. The separate effects of climate change, glacioeustacy, and regional and local tectonic movements on fluvial terrace formation are discussed. This shows that in many published terrace correlation schemes for tectonically active regions, the effects of multi-scale tectonics are insufficiently incorporated or considered. The same applies for the possible effects of variable uplift pulses over middle to late Quaternary timescales. This leads for instance to the separation of fill and strath terraces in a chronological context, because they are still thought to be the resultant of climate-triggered changes in discharge and sediment load of the river. But this thesis shows that they can form at the same time due to localised tectonic movements. The Chapter concludes with a number of recommendations on how to incorporate tectono-geomorphic analysis in fluvial terrace research, which will lead to a better understanding of tectonic control on fluvial terrace formation world-wide.

    Substratum associations of benthic invertebrates in lowland and mountain streams
    Schröder, M. ; Kiesel, J. ; Schattmann, A. ; Jähnig, S.C. ; Lorenz, A.W. ; Kramm, S. ; Keizer-Vlek, H.E. ; Rolauffs, P. ; Graf, W. ; Leitner, P. ; Hering, D. - \ 2013
    Ecological Indicators 30 (2013). - ISSN 1470-160X - p. 178 - 189.
    macroinvertebrate assemblages - community structure - species assemblages - habitat type - bioassessment - rivers - reach - microdistribution - quality - sites
    The preferences of aquatic invertebrate species for specific substrata at the river bottom have been subject of many studies. Several authors classified the substratum preferences of species or higher taxonomic units. Most of these compilations, however, are based on literature analyses and expert knowledge as opposed to the analysis of original data. To enhance our knowledge of invertebrate substratum preferences, we applied a ‘Multi-level pattern’ analysis based on almost 1000 substrate-specific invertebrate samples. The samples were taken in 18 streams in Germany, the Netherlands and Austria, comprising a total of 40 sampling sites and equally covering lowland and mountain streams. The main objectives of our analysis were (I) to derive substratum preferences of taxa in lowland and mountain streams, (II) to compare the preferences with existing data and (III) to compare species substratum associations between lowland and mountain streams. Of the 290 taxa analyzed, 188 were associated significantly to specific substrata. Twenty-five taxa in lowland streams and 51 taxa in mountain streams prefer one or two substratum types (of nine substratum types considered in total). In contrast, 112 species (mountain streams n = 84, lowland streams n = 28) are associated significantly with a broader range of substrata. We compared the classifications derived from our data analysis with those provided in the freshwaterecology.info database (www.freshwaterecology.info). Our results support the existing classifications of substratum preferences in most cases (70%). For 25 species, substratum preferences for both lowland and mountain streams were derived, many of them indicating different substratum associations in the two stream groups. As substratum preferences differed between closely related species, preferences should always be given at the species level as opposed to coarser taxonomic units
    Modelling water quantity and quality using SWAT : a case study in the Limpopo River basin, South Africa
    Querner, E.P. ; Zanen, M. - \ 2013
    Alterra : Wageningen (Alterra-report 2405) - 70
    waterkwaliteit - water - waterbeheer - modelleren - modellen - rivieren - zuid-afrika - water quality - water - water management - modeling - models - rivers - south africa
    In the EAU4Food project the enormous challenges African agriculture is facing today are addressed: the agricultural productivity must increase in the coming years. At present the increase in food production cannot keep up with the population growth. In the coming years irrigation will gain importance, but at the same time the availability of fresh water and the sustainable use of soil resources is under increasing pressure. Hence, new approaches are required to increase food production in irrigated areas in Africa, while ensuring healthy and resilient environments. The need to use less water to produce crops requires innovative approaches. By using models the aim is to analyse feasible measures to improve water efficiency and to reduce negative impacts. The SWAT model has been applied in the Nsama sub-basin, which is situated within the Letaba basin in South Africa. SWAT is a conceptual, physically based hydrological model using daily time steps. In SWAT, a basin to be modelled is divided into multiple sub catchments, which are then further subdivided into Hydrologic Response Units (HRUs) that consist of a homogeneous land use, management, ground slope, and soil characteristics. Flow generation, sediment yield, and non-point-source loadings from each HRU in a sub catchment can be simulated. The purpose of this case study is to use the SWAT model to analyse the effects of changes to the hydrological system. Because of the lack of data, the model could not be calibrated, instead a sensitivity analysis was carried out. Measured discharges from the Letaba basin were scaled down to the Nsama in order to compare at that level measured and calculated discharges. As a test case two scenarios were modelled, being a change in land use and the effect of a DDT application. Based on the experience of this try-out with the SWAT model and the ArcSWAT user interface, the model will be used further for analysis of agricultural production changes and their effects on water quantity and quality.
    Discharge regimes, tides and morphometry in the Mahakam delta channel network
    Sassi, M.G. - \ 2013
    Wageningen University. Promotor(en): Remko Uijlenhoet, co-promotor(en): Ton Hoitink. - [S.l.] : s.n. - ISBN 9789461734679 - 186
    delta - afvoer - getijden - kanalen - kanalen, klein - morfometrie - sediment - rivieren - indonesië - deltas - discharge - tides - canals - channels - morphometrics - sediment - rivers - indonesia

    The Mahakam delta in Indonesia constitutes a text book example of a mixed tide and fluvial dominated delta. Understanding the factors that control the division of water and sediment discharge over channels in the delta is relevant in the contexts of geology, ecology and river engineering. In the Mahakam river and its delta, the tide interacts with the river outflow. River-tide interaction exerts an influence on the discharge regimes and on the division of water and sediment at the bifurcations in the delta. Bifurcations control the dispersal of sediments that eventually govern the shape and evolution of the delta. In this thesis, spatial and temporal aspects of delta evolution are shown to be reflected in scaling relations between the geometric properties of delta channels and the discharge conveyed by the channels, which is known as downstream hydraulic geometry (HG). Downstream HG relations as established in this research, feature a transition from the landward part to the seaward part of the delta characterized by a clear break in scaling behavior. The variation of river discharge throughout the network is largely impacted by river-tide interaction, which is captured by downstream HG relations.

    Impact of farm dams on river flows; A case study in the Limpopo River basin, Southern Africa
    Meijer, E. ; Querner, E.P. ; Boesveld, H. - \ 2013
    Wageningen : Alterra (Alterra-rapport 2394) - 62
    dammen - landbouw - rivieren - regenwateropvang - irrigatiebehoeften - zuidelijk afrika - dams - agriculture - rivers - water harvesting - irrigation requirements - southern africa
    The study analysed the impact of a farm dam on the river flow in the Limpopo River basin. Two methods are used to calculate the water inflow: one uses the runoff component from the catchment water balance; the other uses the drainage output of the SIMFLOW model. The impact on the flow in a sub-catchment with and without the presence of a farm dam, has been analysed. Different farm dam storage capacities and infiltration rates of the soil were considered. In general, the change in natural flow is decreasing when the farm dam capacity becomes higher. On the other hand, the Remaining Natural Flow is increasing when the catchment area becomes larger. The Crop Water Availability was expressed as the relative difference between the crop water requirements and the amount of water supplied by precipitation and irrigation from the farm dam. For a given storage capacity of the farm dam the change in natural flow is calculated when the farm dam covers 90% of the potential evapotranspiration of maize.
    Climate-driven fluvial development and valley abandonment at the last glacial-interglacial transition (Oude IJssel-Rhine, Germany)
    Janssens, M.M. ; Kasse, C. ; Bohncke, S.J.P. ; Greaves, H. ; Cohen, K.M. ; Wallinga, J. ; Hoek, W.Z. - \ 2012
    Netherlands journal of geosciences 91 (2012)1-2. - ISSN 0016-7746 - p. 37 - 62.
    Complex response - Fluvial geomorphology - Lateglacial lower rhine - River pattern change - Vegetation development

    In the Weichselian, the Lower Rhine in the Dutch-German border region has used three courses, dissecting ice-marginal topography inherited from the Saalian. In the Late Weichselian, the three courses functioned simultaneously, with the central one gaining importance and the outer ones abandoning. This study aims to reconstruct the fluvial development and forcings that culminated in abandonment of the northern branch 'Oude IJssel-Rhine', at the time of the Lateglacial to Holocene transition. The fluvial architecture is studied using a cored transect over the full width of the valley, detailed cross-sections over palaeochannels and geomorphological analysis using digital elevation and borehole data. Biostratigraphy, radiocarbon dating and OSL dating provide a timeframe to reconstruct the temporal fluvial development. In its phase of abandonment, the fluvial evolution of the Oude IJssel-Rhine course is controlled by the ameliorating climate and related vegetation and discharge changes, besides by intrinsic (autogenic) fluvial behaviour such as the competition for discharge with the winning central branch and the vicinity of the Lippe tributary confluence. The rapid climate warming at the start of the Late Glacial resulted in flow contraction as the initial response. Other fluvial geomorphic adjustments followed, with some delay. An aggrading braided or transitional system persisted until the start of the Altered, when channel patterns finally changed to meandering. Floodplain incision occurred at the Allerad - Younger Dryas transition and a multi-channel system developed fed by Rhine discharge. At the start of the Holocene, this system transformed into a small-scale, local meandering system, which was abandoned shortly after the start of the Holocene. The final abandonment of the Oude IJssel-Rhine and Niers-Rhine courses can be attributed to deep incision of the Central Rhine course in the earliest Holocene and is considered to be controlled by flow contraction induced by climate and related vegetation and discharge changes.

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