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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Water use in a heavily urbanized delta : scenarios and adaptation options for sectorial water use in the Pearl River Basin, China
Yao, Mingtian - \ 2017
University. Promotor(en): Pavel Kabat, co-promotor(en): Saskia Werners; Ronald Hutjes. - Wageningen : Wageningen University - ISBN 9789463438230 - 175
water use - water management - water resources - socioeconomics - salt water intrusion - water deficit - china - watergebruik - waterbeheer - watervoorraden - sociale economie - zoutwaterindringing - watertekort

Water use is increasing globally to meet the growing demand for food and industrial products, and the rising living standard. Water scarcity has been reported in many regions, questioning the long-term sustainability of water use. The objective of this thesis is to better understand sectorial water use development in an urbanizing river delta, and to explore the potential of water use management as an adaptation option to reduce water shortage. The Pearl River Basin in Southern China is taken as study area. The upstream part of the basin is one of the poorer regions of China, whereas the Pearl River Delta (PRD) is the world’s largest urban region in both population and area. This study presents the first consistent analysis of sectorial water use in the PRD. Results show that during the period of 2000-2010, the PRD managed to stabilize its annual total water use. Nevertheless, severe salt intrusion induced water shortages occur. Assessment of water use at a monthly resolution shows that water use contributes to salt intrusion by further reducing the already low dry season river discharge.

To investigate the possible future development of water use, this study proposed a method to derive region specific water use scenarios from a global assessment of water use. Scenarios based on regionalised assumptions project substantially lower water use than those based on national assumptions. Nevertheless, hydrological challenges remain for the PRD. The total water use of the PRD may still increase by up to 54% in 2030 in the regionalized scenarios. Also, water use in the upstream regions increases with socio-economic development. To address water shortage, four extreme water allocation strategies were analysed against water use and water availability scenarios under climate change. None of these strategies proved to be sufficient to fully avoid water scarcity in the Pearl River Basin.

This study obtains a better understanding of the sectorial water use development and its impact on salt intrusion induced water shortage in a heavily urbanized river delta. The water use framework and methods used to derive regional water use scenarios are transferable to other regions, provided that data is available. Water use scenarios are crucial to sustainably manage water resources in a changing world.

Bringing in the floods : a comparative study on controlled flooding in the Dutch, Bangladesh and Vietnamese deltas
Staveren, Martijn F. van - \ 2017
University. Promotor(en): Jan van Tatenhove, co-promotor(en): Jeroen Warner; Flip 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

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.

Hydrological drought and wildfire in the humid tropics
Taufik, Muh - \ 2017
University. Promotor(en): Remko Uijlenhoet, co-promotor(en): Henny van Lanen. - Wageningen : Wageningen University - ISBN 9789463436359 - 99
wildfires - drought - humid tropics - wetlands - hydrology - prediction - water management - natuurbranden - droogte - humide tropen - hydrologie - voorspelling - waterbeheer

Drought is a recurrent hazard, which has happened throughout human history, and it is anticipated to become more severe in multiple regions across the world. Drought occurs in all climate regimes from humid to dry and from hot to cold. Drought is often viewed through its impact on environment and society, including wildfire, which is the topic of this study. The nature of such impacts differs remarkably from region to region. Although drought does not directly cause wildfire, it provides favorable conditions for wildfire ignition and spread. When drought coincides with strong El Niño events in the humid tropics, e.g. Southeast Asia, the impacts worsen through uncontrolled forest fires affecting the global carbon cycle. These include reduction of the carbon stock, intensifying the haze hazard, and other severe socio-economic impacts in Southeast Asia, including areas far away from the burnt area, e.g. Singapore because of fires in Sumatra.

There still remains a serious lack of scientific understanding about the fundamental role of drought in fire-generating processes. Most research, so far, suggests that climate controls wildfire occurrence in the humid tropics. However, this climate-centered approach, which is reflected in contemporary drought-fire related indices, overlooks soil and hydrological processes beneath the surface across the humid tropics. There is also uncertainty about the relative roles of climate variability and human activities in influencing the nature and distribution of drought-related wildfires. Hence, the general objective of this PhD research is to examine how characterization of hydrological drought under natural and human-modified conditions can improve understanding of wildfires in general in the humid tropics.

Chapter 2 discusses the contribution of humans to an increase of hydrological drought severity in the tropical peatland of Southeast Asia. Climate variability induces drought in the region, however, human activities (human-modified drought) may increase its severity. Analyzing long time series of simulated historical groundwater levels from selected regions in Southeast Asia, which were validated against some years with observations, revealed that human interference (through canalization and land-use change) has amplified drought severity. The drought amplification due to human interference was at least double that of climate-induced drought. The amplification is even higher when peatland is converted into acacia plantation. Further, research findings suggest that even if the Paris Agreement target is met, drought risk of peatlands remains high unless sustainable water management receives top priority in the region.

Chapter 3 deals with how an existing, well-known drought-fire related index, i.e. the Keetch-Byram Drought Index (KBDI), is modified to improve applicability in the humid climate environment of Southeast Asia. The improvement includes: (i) adjustment of the drought factor to the local climate, and (ii) addition of the water table depth as a dynamic factor to fine-tune the drought index. The results indicate that the modified Keetch-Byram Drought Index (mKBDI) performed well in predicting fire hazard. Furthermore, the research identified a critical water table depth, which represents maximum fire hazard (0.85 m for the wetland forest of South Sumatra). Below this value hazard does not increase anymore. The mKBDI could be more widely applied, if pedotransfer functions would be developed that link easily-obtainable soil properties to the parameters of the water table factor.

Chapter 4 shows that wetland transformation (i.e. through canalization and land-use change) not only affects hydrological drought (Chapter 2), but also influences fire behaviour. In Southeast Asia, expansion of agricultural cropland and forest plantations has changed the landscape of wetlands. The findings showed that the transformation into acacia plantation has amplified the fire hazard from 4% (under natural conditions) to 17%. An even higher amplification (40% fire hazard) is expected under poor water management, that is, uncontrolled drainage. The findings derived from this observation-based modeling experiment suggest that improved water management (controlled drainage with higher dry season surface water levels) can minimize fire susceptibility.

Chapter 5 explains the importance of hydrology for fire hazard studies. Borneo is selected to investigate the added value of including hydrological variables in fire hazard prediction approaches. More than 300 statistical models were tested, and the results showed that models that include hydrological variables better predict area burnt than those solely based on climate indicators/indices. Further, modelling evidence shows amplifying wildfires and greater area burnt in response to El Niño Southern Oscillation (ENSO) strength, when hydrology is considered. These results highlight the importance of considering hydrological drought for wildfire prediction. I recommend that hydrology should be considered in future studies of the impact of projected ENSO strength, including effects on tropical ecosystems and biodiversity conservation.

The contributions of this thesis research to science are summarized and synthesized in Chapter 6. First, the research identified that fire hazard studies would benefit from adding hydrology, which is reflected in the improved model performance when hydrological variables are integrated. Next, the research revealed that humans play a substantial role in modifying groundwater drought characteristics, hence amplifying the fire hazard in Southeast Asia. Further, the chapter identified several relevant research findings, including the model choice, which should consider the simplicity and the applicability of the model. Another finding demonstrated that controlling canal water level through canal blocking is a practical water management tool to restore degraded wetland. This restored wetland would benefit some endemic species. However, the restored wetland still faces high drought severity. Hence they remain more fire-prone until the un-impacted hydrology condition is achieved. Finally, this research suggest that currently widely-used drought indices (such as FWI) require improvements in their model structure, which means integration of hydrological variables to increase their applicability for fire hazard studies in the humid tropics.

Mining water governance : everyday community-mine relationships in the Peruvian Andes
Sosa Landeo, Milagros - \ 2017
University. Promotor(en): Rutgerd Boelens, co-promotor(en): Margreet Zwarteveen. - Wageningen : Wageningen University - ISBN 9789463436762 - 200
mining - water policy - governance - water rights - water management - rural communities - local population - water resources - andes - peru - mijnbouw - waterbeleid - waterrechten - waterbeheer - plattelandsgemeenschappen - plaatselijke bevolking - watervoorraden

This thesis documents as well as questions how the presence of large mining operations in Andean regions of Peru alters social and natural landscapes. Taking conflicts over water as a useful entry-point for the analysis, it explores and unravels the dilemmas and challenges faced by the main conflicting actors: rural communities and mining companies. Through an in-depth analysis of how the actors navigate these challenges, focusing on those related to water, the thesis sets out to understand what happens with water in contexts of mineral extraction. It traces changes in how water is accessed, controlled and governed, and by whom. By making the complex character of water politics in mining contexts explicit, the thesis sheds light on how mining reconfigures water governance arrangements, while also contributing to wider debates about water governance in contexts characterized by huge power differences.

Literatuurstudie waarde halen uit groenresten in het waterbeheer
Doorn, Wim van; Kooij, Aldert van der; Dam, Jan van - \ 2017
Amersfoort : Stichting Toegepast Onderzoek Waterbeheer (Stowa rapport 2017-04) - ISBN 9789057737404 - 93
reststromen - biobased economy - waterbeheer - bioraffinage - grasmaaisel - waterplanten - composieten - residual streams - water management - biorefinery - grass clippings - aquatic plants - composite materials
Dit rapport beschrijft de resultaten van de verkennende literatuurstudie naar de mogelijkheden voor verwaarding via bioraffinage van vrijkomend maaisel en in het waterbeheer af te voeren waterplanten. Daartoe is een inventarisatie gemaakt van de vrijkomende hoeveelheden en samenstelling van maaisels bij de acht deelnemende waterschappen en is via een literatuurstudie informatie verzameld over de fysisch-chemische samenstelling van de meest voorkomende planten in de maaisels. Daarbij is een literatuurscan uitgevoerd van de wetenschappelijke literatuur naar wat bekend is over biomassa samenstelling van de meest voorkomende niet-inheemse waterplanten en de aanwezigheid van specifieke inhoudstoffen voor verwaarding. Op basis van deze informatie en inzicht in biobased conversie technieken, is een inschatting gemaakt van het potentieel voor verwaarding van deze groenresten door waterschappen. Mogelijke producten zijn eiwitten voor veevoeder of technische toepassingen, vezels voor papier/karton of diverse biocomposiet-toepassingen, en soms zijn specifieke inhoudstoffen aanwezig, zoals gelerende stoffen of antioxidantia.
Maatgevende afvoer en maaiveldafvoer in waterschap Vechtstromen : beschouwing over de bruikbaarheid van afvoernormen voor bepaling van veranderingen in de waterhuishouding en het optreden van maaiveldafvoer
Massop, H.Th.L. ; Bakel, P.J.T. ; Louw, P.G.B. de - \ 2017
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2839) - 71
drainage - waterbeheer - afvoer - oppervlakkige afvoer - klimaatverandering - nederland - water management - discharge - runoff - climatic change - netherlands
Dit rapport beschrijft (1) een evaluatie van de MA-methodiek (Maatgevende Afvoer) toegepast door harmonisatie van de legger van het waterschap Vechtstromen en brengt (2) de maaiveladafvoer voor het waterschapgebied in beeld.
Evaluating rainwater harvesting systems in arid and semi-arid regions
Ammar, Adham Ali - \ 2017
University. Promotor(en): Coen Ritsema, co-promotor(en): Michel Riksen; M. Quessar. - Wageningen : Wageningen University - ISBN 9789463431460 - 207
water harvesting - rain - water - arid zones - semiarid zones - geographical information systems - water management - climatic change - tunisia - iraq - regenwateropvang - regen - aride klimaatzones - semi-aride klimaatzones - geografische informatiesystemen - waterbeheer - klimaatverandering - tunesië - irak

Rainwater harvesting (RWH) is an ancient traditional technology practised in many parts of the world, especially in arid and semi-arid regions (ASARs). ASARs represent 40% of the earth’s land surface and are characterised by low average annual rainfall and uneven temporal and spatial distributions of that rainfall. In these regions an efficient use of the limited amount of rainfall available is important, e.g. by collecting and using surface runoff (water harvesting). Lately, access to water for agriculture and domestic use has become worse because of increasing population, higher levels of human activity and the impacts of climate change. The inhabitants of ASARs have developed several RWH techniques to increase the water availability, thus coping with water shortages. RWH is an important mitigation strategy to the impact of climate change on water availability in ASARs.

Four main methodologies of site selection were categorised, ranging from those based only on biophysical criteria to more integrated approaches that include socioeconomic criteria. Our analysis suggests that the integration of multi-criteria analysis (MCA) with a geographic information system (GIS) is the most advanced approach. It offers high potential in data-poor regions; GIS-based hydrological modelling is always recommended for data-rich regions.

The potential for RWH in wadi Horan (western desert of Iraq) was identified using a GIS-based suitability model. The method for selecting suitable sites for RWH was then further developed into an evaluation and decision support tool for assessing the overall performance of existing RWH systems by integrating engineering, biophysical and socioeconomic criteria using MCA supported by GIS. It was tested in the wadi Oum Zessar in southeastern Tunisia.

A simple but generally applicable water harvesting model (WHCatch) was developed to investigate and optimise the performance of the RWH systems under various scenarios of design and management, It was tested in wadi Oum Zessar. The advantages of simulating long-term water balances at the sub-catchment level for improving our understanding of hydrological processes in an RWH system are emphasised. Several solutions for optimising RWH performance in various scenarios are provided.

Finally, the impact of climate change on existing RWH systems in the Oum Zessar watershed under current and future scenarios of climate was investigated. The downscaled maximum and minimum temperatures clearly indicated an increasing trend in the mean monthly temperature and the generated precipitation tended to decrease in the future. It was shown that the combination of changing the flow direction and the spillway height had a large impact on the performance of the RWH systems under current and future conditions. Water management and structural design at the sub-catchment level plays a more important role than climate change in the performance of RWH.

SWAP version 4
Kroes, J.G. ; Dam, J.C. van; Bartholomeus, R.P. ; Groenendijk, P. ; Heinen, M. ; Hendriks, R.F.A. ; Mulder, H.M. ; Supit, I. ; Walsum, P.E.V. van - \ 2017
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research report 2780) - 243
agrohydrology - irrigation - drainage - surface water - soil water - water management - simulation models - salinization - agrohydrologie - irrigatie - oppervlaktewater - bodemwater - waterbeheer - simulatiemodellen - verzilting
Theory description and user manual
Safeguarding water availability for food and ecosystems under global change : modelling and assessment of the role of environmental flows
Pastor, Amandine V. - \ 2017
University. Promotor(en): Pavel Kabat, co-promotor(en): Fulco Ludwig; Hester Biemans. - Wageningen : Wageningen University - ISBN 9789463431767 - 177
water availability - water management - flow - water deficit - food security - food production - global warming - aquatic ecosystems - waterbeschikbaarheid - waterbeheer - stroming - watertekort - voedselzekerheid - voedselproductie - opwarming van de aarde - aquatische ecosystemen

In a context of future population increase and intensification of water cycle by climate change, water demand for irrigation is projected to double. However, freshwater resources have been degraded the last decades especially in rivers via fragmentation, dam contraction and pollution. Flow alteration and degradation lead to 80% of freshwater ecosystem species loss. In this thesis, a robust and reliable Environmental Flow (EF) method was developed for global scale: the Variable Monthly Flow (VMF) method. This method allowed estimating EF deficit at global scale including its origin, timing, frequency and magnitude. By setting EFRs as priority user in a global vegetation and hydrological model (LPJmL), irrigation loss due to EFRs implementation were assessed at 30% leading to 5% global calorie loss. To maintain water allocation to humans and ecosystems under global change, food imports would require to increase by 15% especially from Latin America to South of Asia.

Preserving Urmia Lake in a changing world : reconciling anthropogenic and climate drivers by hydrological modelling and policy assessment
Shadkam, Somayeh - \ 2017
University. Promotor(en): Pavel Kabat, co-promotor(en): Fulco Ludwig; Pieter van Oel. - Wageningen : Wageningen University - ISBN 9789463431866 - 140
lakes - hydrology - climatic change - modeling - water resources - water management - environmental protection - iran - meren - hydrologie - klimaatverandering - modelleren - watervoorraden - waterbeheer - milieubescherming

Urmia Lake, in north-western Iran, is an important internationally recognized natural area designated as a RAMSAR site and UNESCO Biosphere Reserve. Over the last 20 years, the surface area of Urmia Lake has declined by 80%. As a result, the salinity of the lake has sharply increased which is disturbing the ecosystems, local agriculture and livelihoods, regional health, as well as tourism, which could amplify economic, political and ethnic tensions in this already volatile region. In response to that, Iranian government established the ten-year “Urmia Lake Restoration Program (ULRP)” proposing six approaches in terms of controlling, protecting, surveying, studying and supplying water from other sources. This study first assessed the main reasons for the decreased inflow using the Variable Infiltration Capacity (VIC) hydrological model, including reservoirs and irrigation modules. The results showed that climate change was the main contributor to this inflow reduction. However, water resources development, particularly water use for irrigation, has played a substantial role as well. In the second step assessed Urmia lake inflow under future climate change and irrigation scenarios. Then, the (VIC) model was forced with bias-corrected climate model outputs for both the lowest (RCP2.6) and highest (RCP8.5) greenhouse-gas concentration scenarios to estimate future water availability. The results showed that the water resources plans are not robust to changes in climate. In other words, if future climate change is limited due to rapid mitigation measures (RCP2.6) the new strategy of reduction of irrigation water use can contribute to preserve Urmia Lake.

The next step of this study assessed the quantitative impacts of ULRP by introducing a constructive framework. The framework depicts real water saving by distinguishing between water withdrawals, depletion, and demand in the context of uncertainties in future demand and supply. The results showed that although the ULRP helps to increase inflow by up to 57% it is unlikely to fully reach its target for three main reasons. The first reason is decreasing return flows due to increasing irrigation efficiency. The second reason is increased depletion which is due to neglecting the fact that agricultural water demand is currently higher than available water for agriculture. The third reason is ignoring the potential impact of climate change. However, there still can be some additional none-quantifiable barriers and challenges that may cause the failure of the restoration plan. Therefore, in the last step, this study used two types of qualitative data to explore these aspects: first, the opinions from 40 experts and the in-situ observation of some of the ULRP implementation practices. The results indicate a number of challenges for the ULRP implementation including the water use regulations and the agricultural measures. In addition, (water) demand-side measures such as crop pattern changes were more supported, as opposed to supply-side measures.

This thesis showed that the sustainable approach to preserve Urmia Lake should incorporate both demand management (considering socioeconomic complexity) and flexible supply management strategies (to deal with uncertainties in climate variability and change) in a participatory approach. To be prepared for the future, also scenarios with reduced inflow into Urmia Lake, either due to climate change or water resources development, need to be considered to deal with considerable amounts of variability in the current system and with future changes in climate and socioeconomic conditions.

Estimation of soil water storage change from clay shrinkage using satellite radar interferometry
Brake, Bram te - \ 2017
University. Promotor(en): Sjoerd van der Zee; R.F. Hanssen, co-promotor(en): Martine van der Ploeg; G.H. de Rooij. - Wageningen : Wageningen University - ISBN 9789463431637 - 123
soil water - water storage - satellite imagery - satellites - interferometry - shrinkage - clay - water management - water policy - bodemwater - wateropslag - satellietbeelden - satellieten - interferometrie - krimp - klei - waterbeheer - waterbeleid

Measurements of soil water storage are hard to obtain on scales relevant for water management and policy making. Therefore, this research develops a new measurement methodology for soil water storage estimation in clay containing soils. The proposed methodology relies on the specific property of clay soils to shrink when drying and to swell when (re-)wetted, and the capabilities of a remote sensing technique called satellite based radar interferometry (InSAR) to measure centimetre to millimetre scale displacements of the soil surface. The objective of this thesis was to develop the application of InSAR for soil water storage change estimation on the field scale to regional scale. Two relations are investigated: 1) the relation between water storage change and surface elevation change as a result of swelling and shrinkage of a clayey soil; and 2) the relation between these surface elevation changes and InSAR phase observations.

The shrinkage potential of the soil is very important for successful application of radar interferometry to measure vertical deformation as a result of swelling and shrinkage of clay. Therefore, the shrinkage potential and the water storage change-volume change relation (called the soil shrinkage characteristic, SSC) have been quantified in the laboratory for clay aggregates from the study area in the Purmer, the Netherlands. The clay content of the sampled soil ranged from 3.4 to 23.6%. The aggregates had moderate shrinkage potential over the soil moisture content range from saturation to air-dryness. Shrinkage phases were distinguished based on the portion of water content change that was compensated by volume change. Approximately 40-50% of water was released in the normal shrinkage phase, where loss of water is fully compensated by volume change. However, the residual shrinkage phase, where volume change is smaller than water content change, started at approx. 50% normalized soil moisture content (actual moisture content with respect to the moisture content at saturation).

In case of normal shrinkage, soil water storage change can be directly derived from soil volume change. If additionally, clay shrinkage is isotropic, the soil water storage change can be derived from vertical shrinkage measurements. The range of normal and isotropic shrinkage has been assessed in a drying field soil in the study area. To do so, soil water storage change was derived from soil moisture content sensors and groundwater level, and volume change estimates were obtained from soil layer thickness change measurements by ground anchors. Unlike for the aggregates, normal shrinkage was not observed for the field soil, but rather a large degree of linear (basic) shrinkage was observed. In the upper soil layers in the field, normalized soil moisture content below 50% has been observed when drying out. Based on the aggregate SSC, this indicates the occurrence of residual and zero shrinkage in this situation, resulting in less than normal shrinkage when the total unsaturated zone is considered. The water content change-volume change relation thus depends on the scale considered. It was also found that the relation depends on drying intensity, from comparison between shrinkage in a period with prolonged drying and shrinkage in a period with alternating drying end re-wetting.

For the field soil, volume change larger than soil water storage change was observed when assuming isotropic shrinkage. This unrealistic result made clear that the assumption of isotropic shrinkage is invalid. Therefore a correction of the shrinkage geometry factor rs, including dependence of shrinkage geometry on soil moisture content, has been proposed. This correction yielded rs-values between 1.38 and 3. Dynamics of subsidence porosity (i.e. vertical shrinkage) calculated from the aggregate SSC, and comparison with surface elevation change data from the field study also indicated rs-values smaller than 3. Values of rs below 3, indicate that vertical shrinkage (subsidence) is dominant over horizontal shrinkage (cracking).

Satellite based radar interferometry was applied to measure vertical deformation resulting from clay shrinkage, and evaluate the potential for soil water storage change estimation on the field scale to regional scale. Phase differences between adjacent fields were observed in interferograms over the Purmer area which were hypothesised to be caused by relative motion of the surface level. The combination of a sequence of interferograms covering short time intervals and measurements of soil surface elevation changes in time from ground anchors, indeed revealed similar dynamics in both data. Relative changes between fields in winter were explained by a different effect of frost heave in a bare soil and in a soil permanently covered by grass. Noise in interferograms over agricultural fields was successfully reduced, by multilooking over entire fields. The effect of soil type and land use on phase observation was qualitatively assessed, indicating that agricultural crop fields offer the best phase estimates in winter, while grass fields are more coherent in summer. The results underline the need for careful selection of agricultural fields or areas to base InSAR analysis on.

The differential analysis between fields was extended to time series analysis of phase, to obtain deformation estimates with respect to a stable reference, including correction for unwanted phase contributions and temporal phase unwrapping. The correction of unwanted phase contributions specifically included the soil moisture dielectric effect. This effect was considered by predicting interferometric phase based on in situ measured soil moisture contents. The soil moisture dielectric effect was shown to be much smaller than shrinkage phase in our case study. A simple model was developed to estimate vertical shrinkage, using assumption on shrinkage behaviour (normal and isotropic shrinkage) and an approximation of water storage change from precipitation and evapotranspiration data. Using this model, temporal phase unwrapping results were corrected. The corrections for soil moisture dielectric phase and the correction of phase unwrapping both improved vertical shrinkage measurements from InSAR.

The results in this thesis make clear that vertical clay shrinkage can be estimated from InSAR. At the same time, these results show that clay shrinkage is a considerable phase contribution to interferometric phase and can therefore cause unwrapping and interpretation errors when not accounted for. To estimate vertical clay shrinkage from InSAR, a shrinkage model including assumptions of normal and isotropic shrinkage, proved useful in the phase unwrapping procedure in this case study. However, using the same assumptions to compute water storage change from these InSAR estimates, will in many cases produce inaccurate results. Therefore, in order to use InSAR for estimating soil water storage change in clay soils, the soil shrinkage characteristic, soil moisture dependency of the shrinkage geometry factor, and the effect of variable drying and wetting conditions, need to be considered.

Eco-engineering for clarity : clearing blue-green ponds and lakes in an urbanized area
Waajen, Guido W.A.M. - \ 2017
University. Promotor(en): Marten Scheffer, co-promotor(en): Miguel Lurling. - Wageningen : Wageningen University - ISBN 9789463431095 - 306
ponds - lakes - ecological engineering - urban areas - cyanobacteria - eutrophication - water quality - water management - plassen - meren - natuurtechniek - stedelijke gebieden - cyanobacteriën - eutrofiëring - waterkwaliteit - waterbeheer

Small lakes and ponds are common features in urban areas and they contribute to the quality of citizens’ life. A poor water quality, however, can easily give rise to nuisance. A major cause for a poor water quality is a high concentration of plant-nourishing nutrients, eutrophication. In (semi-)standing waters, eutrophication often results in a high biomass of blue-green algae (cyanobacteria), turbid water and the disappearance of submerged aquatic plants. The cyanobacterial blooms can be accompanied with fish kills due to anoxia, the development of unpleasant surface scums and malodors. As cyanobacteria can produce potent toxins, they impose a serious risk for citizens’ health, pets and wildlife. The cyanobacterial blooms hamper the anthropogenic use of the water and can have negative economic impacts. Water managers experience that the reduction of cyanobacterial nuisance is arduous. As long-term positive effects of management interventions are not often achieved, there is need for effective approaches.

The objective of this study was to investigate the efficacy of promising methods to reduce cyanobacterial nuisance in city waters, targeting the clear water state and promoting the growth of aquatic plants. Various methods were tested, in the laboratory, in small and large compartments and were eventually applied in whole ponds and lakes. It is widely accepted that the reduction of nutrient inputs is essential for long-term positive effects. This study focused on the reduction of the input and the availability of the key-nutrient phosphorus. It was shown that cyanobacterial nuisance was wide spread in urban ponds and lakes in the Dutch province of North Brabant. The phosphorus inputs of four urban lakes in this province were addressed. The study lakes differed greatly in the phosphorus sources and loads, depending on site-specific characteristics. These differences affected the selection of measures. It was shown that in-lake measures were effective in realizing the long-term abatement of the cyanobacterial nuisance, provided the external phosphorus input was limited. If the external phosphorus input could not be limited sufficiently, in-lake measures did not result in the long-term reduction of cyanobacterial nuisance.

To reduce the bioavailable phosphorus stock in the lake with in-lake measures, sediment capping with a phosphorus-binding agent (lanthanum-modified bentonite, LMB) can be effective and cheaper than sediment removal by dredging. The additional use of a flocculant may have added value and suppressed cyanobacterial blooms quickly and effectively. Aquatic plants and macroinvertebrates responded positively to the achieved improvement of the water quality. Accumulation of lanthanum was shown in aquatic plants and fish, following LMB exposure. No toxic effects of lanthanum from LMB were observed. Depending on site-specific characteristics, dredging or LMB did not suffice to limit the available phosphorus stock in the lake. For this situation, the additional capping of the sediment with sand was tested and subsequently applied in a lake. Management of the fish biomass and lake reconstruction can support rehabilitation. The results of this study underpin the importance of a site-specific diagnosis (water system analysis). The diagnosis clarifies the underlying causes of cyanobacterial nuisances and is essential for a site-specific tailored set of measures. This study showed that a site-specific set of measures reduced cyanobacterial nuisance effectively for a long term.

As eutrophication control is not always feasible or might be effective only in the long run, curative measures are needed for symptom relief. Several curative end-of-pipe measures that are often suggested were evaluated: effective microorganisms (EM®), golden algae, plant extracts, ultrasound and artificial mixing of non-stratifying waters. No strong support for the efficacy of these measures could be shown. Next to the above mentioned application of flocculant, the use of freshwater quagga mussels is promising. The efficacy of the mussels was experimentally tested and it was shown that the introduction of mussels in a hypertrophic urban pond reduced the phytoplankton biomass, including cyanobacteria, and induced a clear water state. The quagga mussel is an invasive alien species and new introductions should be considered carefully.

Based on the results from this study, the thesis provides a road map for water managers for the reduction of cyanobacterial nuisances in urban ponds and lakes.

Advies inrichting en beheer beekdal Geeserstroom
Verdonschot, Piet F.M. ; Verdonschot, Ralf C.M. ; Jansen, Peter C. ; Massop, Harry T.L. ; Grootjans, Ab P. - \ 2017
Wageningen : Wageningen Environmental Research (Alterra) - ISBN 9789463431279 - 128
beekdalen - waterlopen - milieubeheer - natuurbeheer - waterbeheer - wetlands - drenthe - brook valleys - streams - environmental management - nature management - water management
De in 2005 uitgevoerde herinrichting van het beekdal van de Geeserstroom bestond uit de omvorming van een regulier landbouwgebied naar een door natuurlijke waterhuishoudkundige processen aangestuurd natuurgebied, met een nevenfunctie voor waterberging. Vooraf was een 19de -eeuwse beekdallandschap voorzien, met in het midden een stromende beekloop. Het beekdal blijkt zich in de periode tot 2016 echter ontwikkeld te hebben tot een zogenaamd doorstroommoeras, dat inmiddels een grote diversiteit aan moerasvegetaties en een zeer soortenrijke moerasvogelgemeenschap kent. Een doorstroommoeras is een mengvorm van moeras en beek en vormt qua watertype een overgang tussen stromend en stilstaand water. Naast de genoemde ecologische waarden zijn er lokaal echter ook enkele waterhuishoudkundige knelpunten en waterkwaliteitsproblemen ontstaan.
Towards Water Smart Cities : climate adaptation is a huge opportunity to improve the quality of life in cities
Hattum, Tim ; Blauw, Maaike ; Bergen Jensen, Marina ; Bruin, Karianne de - \ 2016
Wageningen : Wageningen University & Research (Wageningen Environmental Research rapport 2787) - 60
water - waterbeheer - stedelijke gebieden - steden - klimaatverandering - klimaatadaptatie - water management - urban areas - towns - climatic change - climate adaptation
Effectief inlaatregiem zoetwatervoorziening Pilot modellering €ureyeopener voor het Hoogheemraadschap Hollands Noorderkwartier
Schipper, Peter ; Veldhuizen, Ab ; Kroes, Joop - \ 2016
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2757) - 35
waterbeheer - zoet water - regionaal beleid - verzilting - beschadigingen door zout - landbouw - noord-holland - polders - water management - fresh water - regional policy - salinization - salt injury - agriculture
In de Nederlandse delta is een uitgekiend waterbeheer van wezenlijk belang voor veiligheid en zoetwatervoorziening. Nu het klimaat verandert en kapitaal intensievere landbouw en andere watergebruikers meer zekerheid willen over de levering van zoet water, is de vraag hoe de zoetwatervoorziening kan worden verbeterd en robuust kan worden gemaakt. In veel gebieden hebben de waterbeheerders nog geen goed overzicht hoe het complexe systeem van zoetwateraanvoer tijdens droge perioden functioneert. Dit komt omdat de zoet-zoutpatronen sterk van plaats tot plaats verschillen, inlaten vaak diffuus van aard zijn en niet worden bemeten en watergebruik voor beregening niet wordt geregistreerd. Zij weten daarom in veel gebieden niet hoe effectief het huidige inlaatregiem is en welke maatregelen geschikt zijn om de zoetwatervoorziening te verbeteren. Het modelconcept de €ureyeopener is ontwikkeld om inzichten te bieden in de effectiviteit van de huidige zoetwateraanvoer en effecten van maatregelen. Het model berekent de wateraanvoerbehoefte, zoutgehalten, gewasschades en de kosten en baten van maatregelen. Voor het Hoogheemraadschap Hollands Noorderkwartier (HHNK) zijn de toepassingsmogelijkheden van dit modelconcept voor HHNK onderzocht door voor de Anna Paulownapolder een €ureyeopener model te maken. In dit gebied spelen voor HHNK nadrukkelijk beleidsvragen voor het voorzieningenniveau, de effecten van de nieuwe sluis bij IJmuiden, slim water management (efficiënter doorspoelen) en de extra zoet watervraag vanuit het Markermeer. Tot vóór de modelstudie had HHNK weinig zicht op de effectiviteit van het doorspoelregiem en de consequenties daarvan voor beregening en mogelijk optredende zoutschade. Het opgezette model geeft transparant inzicht in de uitwerking van het doorspoelregiem en de opbrengstderving van gewassen als het zoutgehalte van het polderwater verandert. In deze rapportage worden de stappen en het resulterende model beschreven. Ten opzichte van eerdere modellen is specifiek aandacht besteed aan de modellering van tulpen en de wijze waarop in het model de waterinlaat kan worden geoptimaliseerd. Met het oog op de samenwerking met Deltares en Bakelse Stroom voor het ontwikkelen van regio-specifieke €ureyeopener modellen hebben zij meegewerkt aan een interne werksessie om een conceptversie van het model te beoordelen en verbeterpunten te identificeren. Ook heeft Deltares bijgedragen aan het formuleren van aanbevelingen.
Vochtige bossen, tussen verdrogen en nat gaan : OBN deskundigenteam Nat zandlandschap
Burg, A. van den; Bijlsma, R.J. ; Brouwer, E. ; Waal, R.W. de - \ 2016
VBNE, Vereniging van Bos- en Natuurterreineigenaren - 36 p.
bosbeheer - waterbeheer - bossen - bosecologie - ecohydrologie - grondwater - grondwaterstand - beekdalen - forest administration - water management - forests - forest ecology - ecohydrology - groundwater - groundwater level - brook valleys
Deze brochure is geschreven voor bos- en waterbeheerders, landschapsecologen en provinciale beleidsambtenaren, om hen te stimuleren de vochtige bossen met meer aandacht te bekijken. De brochure beschrijft om welke bostypen het gaat, hoe je deze kunt herkennen, in welke landschappen ze voorkomen en hoe ze functioneren.
Making eco logic and models work : an integrative approach to lake ecosystem modelling
Kuiper, Jan Jurjen - \ 2016
University. Promotor(en): W.M. Mooij, co-promotor(en): J.H. Janse; Jeroen de Klein. - Wageningen : Wageningen University - ISBN 9789462579446 - 192
ecology - models - ecosystems - modeling - aquatic ecology - water management - water quality - databases - ecologie - modellen - ecosystemen - modelleren - aquatische ecologie - waterbeheer - waterkwaliteit - databanken

Dynamical ecosystem models are important tools that can help ecologists understand complex systems, and turn understanding into predictions of how these systems respond to external changes. This thesis revolves around PCLake, an integrated ecosystem model of shallow lakes that is used by both scientists and water quality managers to understand and predict eutrophication effects in shallow lake ecosystems. Shallow lakes provide some of the clearest examples of alternative stable states in natural systems. PCLake can be used to calculate the critical nutrient loading, that is, the nutrient loading where an abrupt regime shift occurs from a clear aquatic plant dominated state to a turbid phytoplankton dominated state, or vice versa. Four different aspects of modelling with PCLake are addressed in this thesis: (1) making the model better accessible for the modelling community, (2) improving the model, (3) developing scientific theory, and (4) exploring new applications for water quality management.

Following a general introduction to the thesis in chapter 1, the Database Approach To Modelling (DATM) is introduced in chapter 2. DATM is invented to make dynamic models more accessible. The idea of DATM is that the mathematical equations of a model are stored in a database independently of program language and software specific information. From the database, the information can be automatically translated, augmented and compiled into working model code of various different modelling frameworks (software programs).

In chapter 3 the weak link between ecosystem models and real ecosystems is discussed in relation to model calibration and improvement. In a previous stage PCLake has been calibrated using data of more than 40 lakes to obtain a best overall fit, which has greatly increased the scope of the model by making it suitable for more generalized studies on temperate shallow lakes. However, because of this calibration, adding missing functional components to the model at a later stage does not automatically increase the validity of the model, as it may bring the model ‘out of balance’. This is exemplified by adding filter feeding zoobenthos to PCLake, which were previously ignored.

In chapter 4, the relation between food-web theory and alternative stable states theory is scrutinized. Both theoretical paradigms are highly influential in modern ecology as they help scientists understand how stability emerges in complex natural ecosystems. Unfortunately, they developed independently and it is largely unclear how the resilience of a food web relates to the stability of the complete ecosystem. For this study PCLake was used as a virtual reality from which ‘empirical’ information is sampled to parameterize a food web model, following traditional food web methods. This allowed calculating the stability of the food web along a gradient of environmental change, knowing that the complete ecosystem shows a regime shift once the critical nutrient loading is exceeded.

In chapter 5 the question is asked to what extent models of a different form can be used to describe the same natural phenomenon, and hence, how these models can be used for a better understanding of such natural phenomena. Using three classical extensions of the famous Lotka-Volterra equations, which unlike PCLake can be fully mathematically understood, we analyze the consequence of changing a system with a sophisticated functional response term (e.g. Holling type II or III) into a system with a simpler functional response term while maintaining equilibrium densities and material fluxes. These results give new insight into when empirical data can be linked to mathematical models to estimate the stability properties of real ecosystems.

Although PCLake is predominantly applied in the context of ecosystem restoration of turbid phytoplankton dominated lakes, chapter 6 focusses on the clear water state after the reestablishment of aquatic plant dominance as occured. Dense stands of aquatic plants easily cause nuisance, and hence the removal of aquatic plants is an emerging management issue. Yet, because aquatic plants play an important role in stabilizing the clear water state, the removal of plant biomass can potentially trigger a critical transition back to the turbid water state. Currently there is only limited empirical and theoretical understanding of how harvesting of aquatic plants affects ecosystem functioning, which frustrates effective and efficient ecosystem management. With PCLake the impact of harvesting is evaluated, in terms of reducing nuisance and ecosystem stability, for a wide range of external nutrient loadings, mowing intensities and timings. Additionally, the model is used to estimate how much phosphorus is removed from the system during harvesting.

In chapter 7 I discuss the added value of taking an integrative approach to modelling, and discuss the integrated nature of the studies presented in this thesis. It’s also important to note that these studies were part of a larger research project with the overall aim of increasing the usefulness and the validity of PCLake and its twin model PCDitch, and to enhance the confidence in the models among water quality managers. A synopsis of the overarching collaborative research project on PCLake and PCDitch is presented in chapter 8.

Ontzilting; een oplossing voor verzilting in de vollegronds landbouw?
Craats, Daniël van de; Nikkels, M.J. ; Stuyt, L.C.P.M. - \ 2016
H2O online (2016). - 7 p.
verzilting - verziltingsbestrijding - vollegrondsteelt - beschadigingen door zout - waterbeheer - oppervlaktewater - zoet water - ontzilting - salinization - salinity control - outdoor cropping - salt injury - water management - surface water - fresh water - desalination
De huidige manier van omgaan met verzilting in Nederland kan in de toekomst steeds vaker problemen opleveren, onder andere voor beregening in zoutgevoelige teelten. Er wordt daarom nu al aan verschillende oplossingen gewerkt. Eén van de mogelijke oplossingen is ontzilting in de vollegronds landbouw, bijvoorbeeld met behulp van de CapDI-technologie. In deze studie is een theoretische inschatting van de mogelijkheden van dit systeem gemaakt en wordt een praktijktest in de tulpenbollenteelt gepresenteerd. Hieruit blijkt dat er zeker potentie is, maar dat de robuustheid van het systeem, de kosten en de regionale effecten en potentie nog meer aandacht verdienen.
Inventarisatie en analyse zouttolerantie van landbouwgewassen op basis van bestaande gegevens
Stuyt, L.C.P.M. ; Blom-Zandstra, M. ; Kselik, R.A.L. - \ 2016
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2739) - 157
veldgewassen - gewassen - zouttolerantie - verzilting - zoet water - waterbeheer - watervoorziening - field crops - crops - salt tolerance - salinization - fresh water - water management - water supply
In het Deltaprogramma Zoetwater is het lastig gebleken economische analyses te maken voor de programmering van maatregelen en/of de beleidsmatige afweging rond waterbeschikbaarheid. Een van de knelpunten is het gemis aan inzicht in de droogte- en zoutschade in landbouw en natuur. De zoutschade aan landbouwgewassen is nog niet goed in beeld; er zijn veel getallen in omloop, maar de manier waarop deze tot stand zijn gekomen en/of gerapporteerd is niet eenduidig. Daarom is de tussen 1950 en 2015 in Nederland beschikbaar gekomen informatie geanalyseerd. Het resultaat is specificatie van zouttolerantiedrempels voor 35 gewassen en gewasgroepen, gekoppeld aan het zoutgehalte van beregeningswater.
Koeien & Kansen werkt aan beter waterbeheer
Verloop, J. ; Haan, M.H.A. de; Hoving, I.E. ; Noij, I.G.A.M. - \ 2016
V-focus 13 (2016)4. - ISSN 1574-1575 - p. 34 - 36.
melkveehouderij - waterbeheer - agrarische bedrijfsvoering - waterkwaliteit - waterschappen - dairy farming - water management - farm management - water quality - polder boards
Waterbeheer heeft een grotere rol gekregen in het project Koeien & Kansen. In samenwerking met waterschappen werkt Koeien & Kansen aan een instrument waarmee de melkveehouder het waterbeheer op zijn bedrijf in beeld brengt en op een hoger plan kan tillen: de BedrijfsWaterWijzer. Dat is nodig omdat nog te veel kansen worden gemist in het waterbeheer op en rond het melkveebedrijf.
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