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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    Getting a grip on hydrological and sediment connectivity
    Masselink, Rens J.H. - \ 2017
    Wageningen University. Promotor(en): C.J. Ritsema; S.E.A.T.M. van der Zee, co-promotor(en): S.D. Keesstra; A.J.A.M. Temme. - Wageningen : Wageningen University - ISBN 9789463436342 - 158
    hydrology - sediment - land degradation - slopes - geological sedimentation - land management - soil physics - hydrologie - sediment - landdegradatie - hellingen - geologische sedimentatie - grondbeheer - bodemfysica

    Land degradation is a large problem worldwide, especially in agricultural areas. Between 1-6 billion ha of land worldwide is affected by land degradation. With an increasing world population, more food production is needed and, therefore, more land is converted into agricultural areas. This conversion of land to agricultural areas, in turn, leads to more land degradation. Some common forms of land degradation are desertification, salinization and soil erosion by water. The negative effects of soil erosion have been recognized for a long time. Since the early 20th century, researchers have tried to quantify soil displaced due to water, and to measure and model the efficiency of management strategies.

    The implications of problems with upscaling, wrong process representation and equifinality include the difficulty to properly predict sediment sources, pathways and sinks within catchments. These problems then can translate into the implementation of sub-optimal management strategies. To deal with these non-linear processes and the lack of proper representation of water and sediment sources, pathways and sinks, the concept of connectivity was developed. Currently, many definitions of connectivity have been proposed, although the definition most used is that of hydrological connectivity by Pringle (2003): ‘Hydrologic connectivity is the water-mediated transport of matter, energy and organisms within or between elements of the hydrologic cycle’.

    A unified theory on what constitutes connectivity and how connectivity should be measured or inferred remains one of the biggest challenges within catchment science. In addition, it is unclear whether connectivity should be an output or an input of a model and if an input, whether this should be added explicitly or implicitly. The main objective of this thesis was, therefore, to assess and quantify hydrological and sediment connectivity in a meaningful way, which can further our understanding of hydrological and sediment transport processes and catchment system dynamics.

    The study was carried out in three catchments in Navarre, northern Spain. Two catchments, ‘Latxaga’ and ‘La Tejeria’, are agricultural catchments with sizes of 2.07 km2 and 1.69 km2, respectively. The ‘Oskotz Forestal’ catchment is a (semi-)natural catchment, with a size of 5.05 km2. Land cover in the agricultural catchments is mainly winter wheat and barley, while in the Oskotz catchment it is grassland and forest. Latxaga and La Tejeria are mainly underlain by marls and within La Tejeria some sandstone is also present. The geology in Oskotz is characterised by an alternation of marls and sandy limestone.

    In chapter 2, I used networks (graph theory) to characterise and quantify overland flow connectivity dynamics on hillslopes in a humid sub-Mediterranean environment by using a combination of high-resolution digital-terrain models, overland flow sensors and a network approach. Results showed that there are significant differences between overland flow connectivity on agricultural areas and semi-natural shrubs areas. Significant positive correlations between connectivity and precipitation characteristics were found. Significant negative correlations between connectivity and soil moisture were found, most likely due to soil water repellency and/or soil surface crusting. The combination of structural networks and dynamic networks for determining potential connectivity and actual connectivity proved a powerful tool for analysing overland flow connectivity.

    In chapter 3, I determined the functioning of hillslope-channel connectivity and the continuation of transport of these sediments in the channel. To determine this functioning, I obtained data on sediment transport from the hillslopes to the channels while simultaneously looking at factors that influence sediment export out of the catchment. For measuring hillslope-channel sediment connectivity, Rare-Earth Oxide (REO) tracers were applied to a hillslope in the Latxaga catchment preceding the winter of 2014-2015. The results showed that during the winter there have been no sediments transported from the hillslope into the channel. Analysis of precipitation data showed that although total precipitation quantities did not differ much from the mean, the precipitation intensities were low. Using a Random Forest (RF) machine learning method, I showed that hillslope-channel connectivity in Latxaga is dominated by sediment mobilisation during large (high intensity) precipitation events. Sediments are for a large part exported during those events. Large events also leave behind large amounts of sediments in and near the channel, which is gradually removed by small events.

    In chapter 4 I demonstrated that existing data can be used to assess governing factors of connectivity, and how these factors change over time. Data from three catchments in Navarre, Northern Spain, were used to assess factors that influence hydrologic and sediment connectivity. These factors were used as components in a spatially-lumped linear model for discharge and suspended-sediment yield. Three components of connectivity were distinguished: topographical, biological and soil. Changes in the topographical component for the studied periods were considered relatively small, and, therefore, kept constant. Changes in the biological component were determined using the Normalised Difference Vegetation Index. Changes in the soil component were assessed using an Antecedent Precipitation Index. Nash-Sutcliffe model efficiency coefficients were between 0.49 through 0.62 for the discharge models and between 0.23 through 0.3 for the sediment-yield models. I recommended applying the model at smaller spatial scales than catchment scale to minimize the lumping of spatial variability in the components.

    In chapter 5, the objective was to better understand the implications of model calibration at different spatial scales on the simulation of hydrology and sediment dynamics of an agricultural catchment. I applied the LAPSUS-D model to the Latxaga catchment. The model was calibrated and validated (4 years: 2011-2015) using three datasets at varying spatial scales: hillslope, catchment and the combined dataset (combined-calibrated model). The hillslope-calibrated model showed mainly infiltration-excess overland flow, the catchment-calibrated mainly saturation-excess overland flow at the footslopes and the combined-calibrated model showed saturation-excess overland flow from the midslopes to the footslopes. For hydrology, the combined-calibrated model simulated the large discharge peaks best, while at the hillslope scale, the hillslope-calibrated model performed best. The hillslope-calibrated model produced the highest model efficiencies for sediments, for calibration (0.618) and validation (0.269). The hillslope-calibrated model was the only model that showed observed gully erosion on a high-resolution DEM and displayed channel sediment dynamics. However, absolute quantities of erosion and deposition within the catchment were too high. The results show that modellers need to be aware of problems associated with automatic calibration, over-calibration and not incorporating measured data at multiple spatial scales. We advocate incorporating runoff and sediment tracing data at multiple scales whenever this is possible and to, furthermore, carry out specific measuring campaigns towards this end, ultimately to get a more comprehensive view on hydrological and sediment connectivity within a catchment.

    The combination of chapters in this thesis showed that the connectivity concept is useful for a wide range of studies, from hillslope scale to catchment scale. Using the concept, I was able to determine sediment dynamics for a humid-Mediterranean catchment and show that this behaviour is different than previously thought.

    Depending of the aim of the study, various concepts of connectivity are useful. Different geologic and climatic settings cause large differences in catchment (sediment) dynamics. It might, therefore, not be necessary, or even possible, to strive for a single, unifying conceptual framework for connectivity. Instead, a collection of frameworks for different settings should be developed. These frameworks should, however, always aim at helping to understand which measurements need to be taken and which type of models and indices should be used for that particular setting.

    It is my honest opinion that connectivity is definitely a useful concept to advance our knowledge on water and sediment transport processes further. However, careful consideration is also required as this particular concept will not necessary provide the ultimate explanation and insights in dynamic behaviour within watersheds around the world. The gap between the different spatial and temporal scales is too complex to be bridged with a single concept like connectivity. However, the many studies about connectivity that will be published in the near future will be able to advance knowledge on water and sediment transport processes.

    Beach sand dynamics : measurements, models and scales
    Poortinga, A. - \ 2015
    Wageningen University. Promotor(en): Coen Ritsema, co-promotor(en): Saskia Visser; Michel Riksen. - Wageningen : Wageningen University - ISBN 9789462575851 - 235
    stranden - zand - modellen - meettechnieken - eolisch zand - sediment - geologische sedimentatie - beaches - sand - models - measurement techniques - aeolian sands - sediment - geological sedimentation
    Impact of improved operation and maintenance on cohesive sediment transport in Gezira Scheme, Sudan
    Osman, I.S.E. - \ 2015
    Wageningen University. Promotor(en): E. Schultz, co-promotor(en): A.K. Osman; F.X. Suryadi. - Leiden : CRC Press/Balkema - ISBN 9781138028807 - 183
    sediment - geologische sedimentatie - waterbeheer - irrigatiekanalen - irrigatie - irrigatiewater-toedieningsschema - sudan - sediment - geological sedimentation - water management - irrigation channels - irrigation - irrigation scheduling - sudan
    Summary

    Efficient operation and maintenance of irrigation schemes are needed for improving the hydraulic performance of the canals, enhancing the crop yields and insuring sustainable production. There is a great need to enhance the researches and for a variety of tools such as water control and regulation equipment, decision support systems, as well as field surveys and valuation techniques. Water management becomes difficult when dealing with sediment transport in irrigation canals. Most of the studies simulate the sediment transport of relatively coarse grain sizes. The sediment problem in irrigation canals becomes more complicated when dealing with cohesive sediment transport. Therefore, more research is needed to enhance the understanding of the behaviour of cohesive sediment transport under a variety of operation conditions.

    This study has been carried out in the Gezira Scheme in Sudan. The scheme, which is one of the largest irrigation schemes in the world under a single management, is located in the arid and semi-arid region. The scheme is chosen as a case study since it can act as a model for similar irrigation schemes. The scheme has a total area of 880,000 ha and uses 35% of Sudan’s current allocation of Nile waters. This represents 6 – 7 billion m3 per year. The scheme is irrigated from the Blue Nile River, which is characterized by its high load of fine sediment. The scheme is facing severe sediment accumulation in its irrigation canals, which represents a challenge to those responsible for the operation and maintenance of the canals. Each year large investments are required to maintain and to upgrade the canal system to keep it in an acceptable condition.

    A large quantity of cohesive sediment enters the scheme every year. According to previous studies, about 60% of the sediment deposits in the irrigation canals. The sediment accumulation in the canals reduces the canal conveyance capacity, causes irrigation difficulties, creates inequity and inadequate water supply and increases the rate of aquatic weed growth. The sedimentation problems are not only seriously affecting the performance of the irrigation canals, but are also jeopardizing their sustainability, as well as affecting crop production. Two canals in the scheme have been selected to be studied in detail: Zananda Major Canal, which takes water from Gezira Main Canal at 57 km from the offtake at Sennar Dam, and Toman Minor Canal at 12.5 km from the offtake of Zananda Major Canal.

    The hypothesis of the study postulates that the operation and maintenance of an irrigation scheme has a major influence on the hydrodynamic behaviour of canals and hence on sediment movement and deposition. The aim of this study was to improve the operation and maintenance procedures for better sediment and water management. This can be achieved through better understanding of the sediment processes in the irrigation canals of the Gezira Scheme and to understand clearly the link between irrigation system operation and resulting system performance in terms of transport of cohesive sediment.

    Data collection and field measurements have been conducted during the flood season between June and October in 2011 and 2012. Sediment sampling and water level measurements have been conducted on a daily basis at selected locations. The manually recorded water levels include about 1080 readings per year. In addition about 1290 sediment samples were analysed for different locations during the study period. Cross-sectional surveys have been performed at the beginning and end of the flood season to address the spatial and temporal variation of the sediment deposition in the canals under study and to detect changes in the bed profile. The head regulator and outlet control structures were calibrated by using the measured stage-discharge relationships. More elaboration is given to the properties of cohesive sediment and identification of the dominant factors that cause deposition in irrigation canals. Sediment properties were tested such as grain size distribution, mechanical and physico-chemical properties of the sediment. The irrigation schedules, cropped area and sowing dates for different crops were reported. Other data such as canal design data, historical data of the sediment and flow for certain canals were reviewed.

    The analysis of the data indicates a variation of the water level along the canals under study. It should be noted that the operation control in Gezira Scheme is by using upstream control structures. The field data show that the flow release in the system is not regularly adjusted in a systematic way to meet the demand and maintain the required water level. Continuous change in gate setting results in instability of the water level. This situation became worse with more sediment deposition. The water level has been raised far above the design level and there is lapse in working levels especially at the major and minor canals. The rise is found to be about 1.6 and 1.2 m above the design level at the head of the major and minor canals under study. Furthermore, reduction in the water depth has been detected along the canals as result of bed rise and enlarging of canal sections due to improper desilting. The results demonstrate that the supply of water was extremely large during the flood season of 2011 compared to the actual crop water requirement, especially during the period of high sediment concentration. The delivery performance ratio indicated an oversupply at the major canal in 2011 during most of the time. The study also provides some valuable insight into the nature of sediment in Gezira Scheme.

    There is a limitation in the existing models that deal with fine sediment transport in irrigation canals. Most of the sediment transport models are developed for estuaries and rivers. Therefore there was a great need to develop a simple but effective numerical model that incorporates control structures to simulate the fine sediment transport in irrigation canals. Although there are similarities between rivers and irrigation canals, irrigation canals are different. The presence of a large number of flow control structures and the high influence of the side banks on the velocity distribution create some differences in both types of channels. Hence, it was important to develop a model dealing with fine sediment in irrigation canals, including different types of hydraulic structures.

    In line with this the one dimensional numerical model Fine SEDiment Transport (FSEDT) dealing with fine sediment transport in irrigation canals has been developed. The model has been used as a tool to study the mechanism of water and sediment flow under different operation and maintenance scenarios. The water surface profile has been predicted by using the predictor corrector method to solve the gradually varied flow equation. The prediction of sediment concentration is based on the solution of the one dimensional advection-diffusion equation. The bed material exchange was determined based on the Partheniades (1962) and Krone (1965) equations. The change in bed level was computed based on the sediment mass balance equation that was solved numerically by using the finite difference method. The model has been applied in the Gezira Scheme. On the basis of the field data the model has been calibrated and validated. The predicted bed profiles depict good agreement with the measured ones. The model is capable to predict the bed profile for any period of simulation. The model can predict the sediment concentration hydrograph at different points within a canal reach, in addition to the total volume of the sediment deposition in the reach. The output of the model can be presented in tabular or graphical form.

    The sediment transport in the irrigation canals has been simulated by adopting different scenarios. The interrelationship between water flow and sediment transport in the irrigation canals under changing flow conditions has been investigated. Two scenarios of operation were tested at the major canal under study. The model evaluated the indent system that has been applied in Gezira Scheme for many years in regard to sediment deposition. Another proposed scenario based on crop water requirement was also tested. In addition, operation under future changed conditions in case of reduction in the sediment concentration was tested. The different operation scenarios have been compared with the existing condition based on data collected during the flood season in 2011 in terms of sedimentation. Based on this, the following remarks are made:

    the effect of varying crest settings of the movable weirs has been investigated and less sediment deposition was found to occur when the crest level was set at its lowest position. The sediment transport in the canals is influenced by the operation of the hydraulic structures, especially upstream of movable weirs. The effect is extended to about 3 km upstream of the weir;

    for many years the indent system of water allocation was applied in the Gezira Scheme based on duty and cropped area. However, this system of operation has been absent during the last years. The slope of Zananda Major Canal became 13 cm/km and 18 cm/km for the first and second reaches respectivelycampaigns

    the reduction of the water delivery during the period of high concentration between 10 July and 10 August, based on the crop water requirement results in reduction in the sediment deposition by 51 and 55% for the first and second reaches respectively when compared to the situation in 2011;

    the reduction of the Blue Nile River sediment concentration by 50% as result of the construction of the Ethiopia Renaissance Dam and/or improvement in the land use has been simulated. The results of the simulation of the suspended sediment transport at the major canal indicate that the deposition will be 74 and 81% lower for the first and second reaches respectively when compared with the situation in 2011.

    At the minor canals, the night storage weirs were designed as cross structures. The idea behind the night storage system was to store water during the night by closing all field outlet pipes and the gates of the cross structures along the minor canal at 6:00 pm and releasing them at 6:00 am. Although this system has been vanished to keep pace with crop intensification and to cope with the deterioration of the water supply due to the poor maintenance of the canals, this scenario has also been simulated. The hydrodynamic flow in the canals during the filling time has been simulated by using the DUFLOW model since the model can be applied for unsteady flow. A spreadsheet has been designed to predict the deposition every hour based on the output of the DUFLOW model. The night storage system has been compared with the continuous system regarding the sediment transport in addition to other scenarios. It was found that:

    the continuous system reduces the amount of deposited sediment by 55% compared to the night storage system;

    about 29% of the sediment was reduced in 2011 when the system was operated based on crop water requirement;

    the deposition lightly increased with reduced capacity of the field outlet pipes. The

    The main findings and the contributions that are made by this study:

    the study comes up with a model dealing with cohesive sediment in irrigation canals for effective sediment and water management, which can be applied widely for similar irrigation schemes dealing with fine sediment;

    it is possible to improve the sediment and water management by improving the operation and maintenance. The high irrigation efficiency is tending to mitigate the inflow sediment load and as a consequence less deposition is expected;

    the study comes up with strategies of water management that can reduce the deposition in irrigation canals by operating the system continuously based on crop water requirement at the period of high sediment concentration with the field outlet pipes operating at their full capacity.

    The absence of proper maintenance activities and water management has a prominent role in increasing the deposition along the irrigation canals in Gezira Scheme. Improving the operation and maintenance is not the only way to mitigate the sedimentation in the irrigation canals. A great consideration needs to be given to improve the design since conditions based on the original design have been changed with time such as the operation system (night storage system, indent system), cropping intensity and geometry of the canals. In other words, rehabilitation of the system will not be one of the solutions to mitigate the accumulation of the deposition along the canals but the system itself needs remodelling. The developed model can be used to assess the new design and to evaluate the proposed management plans in terms of transport of cohesive sediment.

    Passende Beoordeling Natuurbeschermingswet 1998 voor project Kwelderontwikkeling Koehoal door een slibmotor
    Baptist, M.J. - \ 2015
    Den Burg : IMARES (Rapport / IMARES Wageningen UR C081/15) - 44
    havens - sediment - wetlands - bagger - geologische sedimentatie - natura 2000 - natuurbescherming - waddenzee - friesland - harbours - sediment - wetlands - dredgings - geological sedimentation - natura 2000 - nature conservation - wadden sea - friesland
    Pilotproject om het gebaggerd slib uit de haven van Harlingen te verspreiden over de wadden. In het natura 2000 gebied. Door middel van een experimentele ‘slibmotor’ wordt het sedimentaanbod langs de kust ten noordoosten van Harlingen vergroot met als uiteindelijk doel het areaal kwelders te vergroten.
    Ontwikkeling van eilandstaarten : geomorfologie, waterhuishouding en vegetatie
    Groot, A.V. de; Oost, A.P. ; Veeneklaas, R.M. ; Lammerts, E.J. ; Duin, W.E. van; Wesenbeeck, B.K. van; Dijkman, E.M. ; Koppenaal, E.C. - \ 2015
    Driebergen : VBNE, Vereniging van Bos- en Natuurterreineigenaren (Deltares rapport 1208549.01) - 109
    geomorfologie - geologische sedimentatie - natuurgebieden - kweldergronden - duingebieden - hydrologie - vegetatietypen - nederlandse waddeneilanden - geomorphology - geological sedimentation - natural areas - salt marsh soils - duneland - hydrology - vegetation types - dutch wadden islands
    In deze rapportage worden de oostelijke, buitendijkse delen van de Nederlandse Waddeneilanden behandeld, de zgn. eilandstaarten. Wanneer deze volledig ontwikkeld zijn bestaat ze uit wadplaten, kwelders en duinen. Dit rapport behandelt de geomorfologie, waterhuishouding en vegetatie van eilandstaarten. De ontwikkeling van eilandstaarten is mede van belang voor de functie die ze hebben in de waterveiligheid.
    Veldexperiment in de Hooge Raam: winst voor beekherstel èn wetenschap
    Eekhout, J.P.C. ; Hoitink, A.J.F. ; Mosselman, E. ; Kits, M. ; Talsma, M. - \ 2014
    Stromingen : vakblad voor hydrologen 20 (2014)2. - ISSN 1382-6069 - p. 11 - 21.
    waterlopen - herstel - morfologie - veldproeven - geologische sedimentatie - noord-brabant - streams - rehabilitation - morphology - field tests - geological sedimentation - noord-brabant
    In de beek de Hooge Raam is een beekherstelproject gekoppeld aan een uniek veldexperiment. Het doel van het veldexperiment was om over een periode van drie jaar de temporele morfodynamiek te volgen van een rechte beekloop met een breed en ondiep dwarsprofiel. Ongeveer 8 maanden na aanleg zijn alternerende banken ontstaan. In eerste instantie namen de banklengte en bankamplitude toe. Vervolgens stabiliseerde de banklengte, maar nam de bankamplitude af. Uiteindelijk verdween het regelmatige alternerende bankenpatroon en maakte het plaats voor een grillig bodemprofiel. De dynamiek van de alternerende banken liep parallel aan het verloop van het bodemverhang; het bodemverhang halveerde van initieel 1,8 m/km naar 0,9 m/km. Het uiteindelijke bodemverhang ligt tegen de bovengrens van bodemverhangen die typisch zijn voor laaglandbeken. Het is daarom onwaarschijnlijk dat alternerende banken in laaglandbeken zullen ontstaan. Dit alternatief voor hermeandering is waarschijnlijk niet geschikt voor het herstel van laaglandbeken. Hermeandering lijkt daarom nog steeds de meest effectieve methode om de ruimtelijke stromingsvariatie in Nederlandse laaglandbeken terug te brengen
    Vegetatie en opslibbing in de Peazemerlannen en het referentiegebied west-Groningen: Jaarrapport 2013
    Duin, W.E. van; Leeuwen, P.W. van; Sonneveld, C. - \ 2014
    Den Burg : IMARES (Rapport / IMARES Wageningen UR C026/14) - 56
    wetlands - kustgebieden - vegetatiemonitoring - kweldergronden - geologische sedimentatie - monitoring - friesland - wetlands - coastal areas - vegetation monitoring - salt marsh soils - geological sedimentation - monitoring - friesland
    Deze rapportage beschrijft de monitoring in het kader van de bodemdaling onder de kwelder de Peazemerlannen, gelegen aan de Friese noordoostkust. Er wordt een overzicht gegeven van de activiteiten en meetresultaten in de kwelder en zomerpolder van de Peazemerlannen en het referentiegebied in de kwelderwerken in west-Groningen gedurende de jaren 2007 t/m 2013. De meeste gegevens worden weergegeven vanaf 2007, het startjaar van deze gaswinning.
    Synthesedocument Waddengebied : Achtergronddocument B10
    Gerritsen, H. ; Timmerman, J.G. ; Coninx, I. - \ 2014
    Ministerie van Infrastructuur en Milieu en Ministerie van Economische Zaken - 80
    hoogwaterbeheersing - zoet water - geologische sedimentatie - bodemdaling - veiligheid - natura 2000 - waddenzee - flood control - fresh water - geological sedimentation - subsidence - safety - natura 2000 - wadden sea
    Dit synthesedocument beschrijft hoe de voorstellen voor de voorkeurstrategie in het Deltaprogramma Waddengebied tot stand gekomen zijn. Met dat doel beschrijft dit document in het kort de opdracht van het Deltaprogramma en de wijze waarop het Deltaprogramma naar de voorkeurstrategie heeft toegewerkt. Daarbij gaat het om de randvoorwaarden en uitgangspunten die gehanteerd zijn en om de wijze waarop de vergelijkingssystematiek is toegepast. Bij klimaatverandering ontstaat de opgave om het waddengebied duurzaam veilig te houden en tegelijkertijd de bijzondere waarden te behouden: het waddengebied herbergt zulke bijzondere waarden dat het is opgenomen op de lijst van Werelderfgoed van UNESCO en vrijwel in zijn geheel is aangewezen als Natura 2000-gebied. Het waddengebied bestaat uit de Hollands-Fries-Groningse vaste wal, Waddenzee, Waddeneilanden met de voorliggende kust (kustfundament), Eems-Dollard en de buitendelta’s van de zeegaten. Het waddengebied inclusief Waddenzee en buitendelta's vormt een buffer tegen de hoge golven van de Noordzee door de natuurlijke demping hiervan. Zonder deze buffer zouden de waterkeringen hoger en sterker moeten zijn. De Deltabeslissing Waterveiligheid en de Beslissing Zand vormen het kader voor de voorkeurstrategie voor het waddengebied. In het waddengebied is de voorkeurstrategie gericht op het meegroeien met de zeespiegelstijging. Door de stijgende zeespiegelstijging heeft het intergetijdengebied van de Waddenzee extra zand nodig. Als de zeespiegel versneld stijgt kan het zijn dat het intergetijdengebied en de platen de stijging niet meer kunnen bijhouden. De dempende werking die het waddengebied nu uitoefent op de golven die van de Noordzee komen en de golven die binnen de Waddenzee opgewekt worden, neemt dan verder af. Daardoor bereiken de Noordzeegolven met meer energie de vaste wal. Dat kan leiden tot extra werken aan de primaire keringen om de vaste wal te kunnen blijven beschermen tegen overstromingen. De opgave is het tijdig kunnen waarnemen en kunnen inschatten van de gevolgen van klimaatveranderingen (zeespiegelstijging, windkarakteristieken, temperatuurstijging) en het vinden van zo natuurlijk mogelijke maatregelen om de bufferende werking van het waddengebied te kunnen behouden. In aanvulling hierop is het doel met aangepast kwelderbeheer de natuurlijke opslibbing in de Waddenzee te versterken, mits dat past binnen de voorwaarden van de PKB Waddenzee, de aanwijzing als Werelderfgoed en Natura 2000-instandhoudingsdoelen. Op grond van de huidige kennis zijn tot 2100 geen zandsuppleties in de Waddenzee en het Eems-Dollard estuarium zelf nodig voor de waterveiligheid. Voor de natuurwaarden is dit ook niet wenselijk. Vooralsnog volstaat het om zand te blijven suppleren aan de Noordzeekant van de Waddeneilanden, op het kustfundament, in aanvulling daarop, eventueel op de buitendelta’s. Het werkend leren programma zal uitwijzen of dit zand tijdig op een natuurlijke wijze naar de platen en kwelders van de Waddenzee kan stromen. Voor de eventuele aanpassing van het suppletiebeheer in 2020 vindt kennisontwikkeling plaats over het benodigde volume, de techniek, de frequentie en de locaties van de suppleties. Om zandsuppleties in de toekomst effectiever te kunnen uitvoeren, met behoud van de waarde van het waddengebied, is meer systeemkennis nodig. Deze kennis komt tot stand met een langjarig kennisprogramma, gericht op onderzoek, systeemkennis en monitoring. Het programma gaat in 2015 in uitvoering, onder meer kleinschalige pilots tot 2020 en grootschaliger pilots na 2020. Deze onderzoeken staan in de concept-kennisagenda van het Deltaprogramma. Besluitvorming over de definitieve kennisprogrammering moet nog plaatsvinden en hangt ook samen met het Kennis- en Innovatieprogramma Water en Klimaat. Langs de Hollands-Fries-Groningse vaste wal en de eilanden bieden waterkeringen bescherming tegen overstromingen. De voorkeurstrategie rondom de primaire waterkeringen richt zich op innovatie en een gebiedsgerichte en integrale benadering. Zo’n honderd kilometer van deze keringen voldoet niet aan de normen. Een deel van dit deelgebied krijgt een hogere norm vanwege de aanwezigheid van de gasrotonde. Dijkversterkingen komen tot stand door aanpassingen aan de keringen aan te laten sluiten bij gebiedsontwikkelingen en meerwaarde te creëren voor functies als natuur, recreatie en regionale economie. Langs de Friese en Groningse kust kan dit vrijwel overal met innovatieve dijkconcepten, zoals brede groene dijken, multifunctionele dijken en overslagbestendige dijken. Ook bij Den Helder en Den Oever zijn innovatieve dijkconcepten met meerwaarde voor andere functies mogelijk. Voor de versterking van vijf dijktrajecten langs de Friese en Groningse vaste wal worden tot 2020 verkenningen conform de MIRT-systematiek uitgevoerd (geprogrammeerd in het nHWBP). En verder wordt in de periode 2014-2017 ook een project overstijgende verkenning uitgevoerd voor de gehele Waddenzeedijk langs de Friese en Groningse vaste wal, met deze voorkeurstrategie als basis. Voor ieder Waddeneiland wordt een integrale strategie opgesteld voor het suppletiebeheer (voor en na 2020), dynamisch kustbeheer, kwelderontwikkeling, innovatieve dijkconcepten en rampenbeheersing, en wordt gezocht naar ‘slimme combinaties’. De buitendijkse gebieden worden robuuster voor overstromingsrisico’s door deze risico’s mee te wegen bij ruimtelijke (her)ontwikkelingen, zoals beschreven bij de deltabeslissing Ruimtelijke Adaptatie. De voorkeurstrategie zoetwater in het waddengebied is beschreven bij de voorkeurstrategie van het Deltaprogramma IJsselmeergebied. Voor de Waddeneilanden vormt de deltabeslissing Zoetwater het kader voor de voorkeurstrategie. De Waddeneilanden ontvangen geen zoetwater uit het hoofdwatersysteem. Deze eilanden hebben de ambitie om in 2020 zelfvoorzienend te zijn voor drinkwater. De inzet is de zelfvoorzienendheid voor overig zoetwatergebruik, zoals voor de landbouw, te vergroten. Om watertekorten bij klimaatverandering te beperken, zijn maatregelen mogelijk om regenwater en zoetwaterlenzen nog beter te benutten en het water zuiniger te gebruiken. De eilanden kunnen hiermee een voortrekkersrol vervullen voor andere delen van het land. Het Deltaplan Waterveiligheid en het Deltaplan Zoetwater bevatten de maatregelen uit deze voorkeurstrategie, die op korte termijn in voorbereiding of uitvoering gaan. De programmering van dijkversterkingen vindt plaats in het nieuw Hoogwaterbeschermingsprogramma (nHWBP). Voorgesteld wordt dit voor maatregelen voor zoetwaterbeschikbaarheid ook in samenhang te programmeren en te prioriteren. De partijen die betrokken zijn bij de voorkeurstrategie waterveiligheid voor het waddengebied leggen onderdelen van de strategie vast in hun eigen plannen. Het Deltaplan Waterveiligheid bevat de maatregelen die het Rijk programmeert voor de waterveiligheid in het waddengebied. Het Rijk houdt in het beheerplan voor Natura 2000 rekening met beheer van de kwelders ten behoeve van waterveiligheid. De provincie Groningen legt onderdelen van de voorkeurstrategie vast in het nieuwe omgevingsplan dat in 2015 wordt vastgesteld, onder meer middels ruimere reserveringszones voor innovatieve dijkconcepten. De provincie Friesland neemt onderdelen van de voorkeurstrategie over in de streekagenda’s en het provinciaal waterhuishoudingsplan en de bijbehorende programmeringen. Tot deze onderdelen behoren ook afwegingen over ruimtelijke adaptatie voor de eilanden. Een regionaal bestuurlijk platform beoordeelt of de prioritering van dijkversterkingen in het nHWBP voldoende aansluit bij gebiedsontwikkelingen.
    Modelling the effect of climate change on coastal dunes
    Keijsers, J.G.S. ; Groot, A.V. de; Riksen, M.J.P.M. - \ 2014
    klimaatverandering - erosiegevoeligheid - geologische sedimentatie - duingebieden - modellen - climatic change - erodibility - geological sedimentation - duneland - models
    The size and shape of coastal dunes depends on the balance between accretion and erosion. As both accretion and erosion are driven by climatic forces, our research question is: how does climate change influence dune development ?
    Preparing for climate change: a research framework on the sediment - sharing systems of the Dutch, German and Danish Wadden Sea for the development of an adaptive strategy for flood safety
    Oost, A.P. ; Wang, Z.B. ; Groot, A.V. de; Duren, L.A. ; Valk, L. van der - \ 2014
    Deltares (Rapport / Deltares 1209152-000) - 47
    klimaatverandering - geologische sedimentatie - hoogwaterbeheersing - hydrodynamica - natuurwaarde - wetlands - waddenzee - climatic change - geological sedimentation - flood control - hydrodynamics - natural value - wetlands - wadden sea
    The report proposes a research framework which follows a learning-by-doing approach along the three research lines: monitoring & data analysis, system research & modelling and field experiments (pilots). All studies together will take several decades, partially due to the many questions, partially because studying changes in the system via the above-mentioned research lines takes time. Research programs developed on basis of this framework may focus on a part of the research issues
    Soft engineering vs. a dynamic approach in coastal dune management: a case study on the North Sea barrier island of Ameland, the Netherlands
    Jong, B. de; Keijsers, J.G.S. ; Riksen, M.J.P.M. ; Krol, J. ; Slim, P.A. - \ 2014
    Journal of Coastal Research 30 (2014)4. - ISSN 0749-0208 - p. 670 - 684.
    hoogwaterbeheersing - kustbeheer - duinen - eolische processen - geologische sedimentatie - nederlandse waddeneilanden - flood control - coastal management - dunes - aeolian processes - geological sedimentation - dutch wadden islands - dutch coast - beach - foredunes - erosion - storms
    Dunes act as flood defences in coastal zones, protecting low-lying interior lands from flooding. To ensure coastal safety, insight is needed on how dunes develop under different types of management. The current study focuses on two types of coastal dune management: (1) a “soft engineering” approach, in which sand fences are placed on the seaward side of foredunes, and (2) “dynamic coastal management,” with minimal or no dune maintenance. The effects of these management styles on dune formation are examined for two adjacent coastal sections of the North Sea barrier island of Ameland, The Netherlands, where dynamic coastal management was introduced in 1995 and 1999, respectively.
    Dunes act as flood defenses in coastal zones, protecting low-lying interior lands from flooding. To ensure coastal safety, insight is needed on how dunes develop under different types of management. The current study focuses on two types of coastal dune management: (1) a "soft engineering" approach, in which sand fences are placed on the seaward side of foredunes, and (2) "dynamic coastal management," with minimal or no dune maintenance. The effects of these management styles on dune formation are examined for two adjacent coastal sections of the North Sea barrier island of Ameland, The Netherlands, where dynamic coastal management was introduced in 1995 and 1999, respectively. For each section, we analyzed cross-shore profile data from 1980 until 2010, deriving dune foot position, crest position, crest height, and foredune volume for each year and analyzing the situation before and after the change in management. We further assessed the effect of the management regime on dune vegetation. Other factors that could influence dune development were also taken into account, such as beach width and shape, water levels, wave heights, and nourishments. Results show that implementation of dynamic coastal management did not directly affect the volume of the foredune. Growth was occasionally interrupted, coinciding with high-water events. In periods between erosive storms, dune growth rates did not show a significant difference between management types (p = 0.09 and 0.32 for sections 1 and 2, respectively). The main effect of the change was on vegetation development. Dynamic coastal management, therefore, did not reduce coastal safety.
    Morfodynamiek van Nederlandse laaglandbeken
    Eekhout, J.P.C. ; Hoitink, A.J.F. - \ 2014
    Amersfoort : Stowa (Rapport / Stowa 2014-15) - 92
    waterlopen - herstel - morfologie - geologische sedimentatie - waterkwaliteit - streams - rehabilitation - morphology - geological sedimentation - water quality
    In de eerste helft van de 20ste eeuw zijn veel laaglandbeken in Nederland gekanaliseerd. Dit heeft vaak geleid tot grote veranderingen in de hydrologie en morfologie van beken, met als gevolg een sterke achteruitgang van de bijbehorende karakteristieke aquatische en terrestrische ecosystemen. In de afgelopen 25 jaar zijn de Nederlandse waterschappen begonnen met beekherstel om wateroverlast te voorkomen, verdroging terug te dringen en de ecologische (water)kwaliteit van beeksystemen te verbeteren (KRW). Eén van de meest toegepaste maatregelen hierbij is hermeandering.
    Het Geldernsch-Nierskanaal: hoe een recht kanaal gaat meanderen als gevolg van kwel
    Eekhout, J.P.C. ; Hoitink, A.J.F. ; Makaske, B. ; Talsma, M. - \ 2013
    H2O : tijdschrift voor watervoorziening en afvalwaterbehandeling (2013). - ISSN 0166-8439
    waterlopen - afvoer - kanalen - geologische sedimentatie - kwel - natuurgebieden - midden-limburg - noordrijn-westfalen - streams - discharge - canals - geological sedimentation - seepage - natural areas - midden-limburg - north rhine-westphalia
    Aan het eind van de 18de eeuw is tussen de rivieren de Niers in Duitsland en de Maas in Nederland het Geldernsch-Nierskanaal gegraven, om piekafvoeren in het benedenstroomse deel van de Niers af te vlakken. Het Duitse deel van het kanaal is in de loop van de tijd gekanaliseerd gebleven door oeverbeschoeiing. Opvallend is dat het Nederlandse deel, dat de vrije loop werd gelaten, actief is gaan meanderen. Onderzoek laat zien dat kwel de aanzet gaf voor het meanderen.
    Klimaatbestendige dijken: het concept wisselpolders
    Mesel, I.G. de; Ysebaert, T. ; Kamermans, P. - \ 2013
    Yerseke : IMARES (Rapport / IMARES Wageningen UR C072/13) - 48
    geologische sedimentatie - deltagronden - natuurontwikkeling - landgebruik - landbouw - kustbeheer - bescherming - kustgebieden - westerschelde - zuidwest-nederland - geological sedimentation - delta soils - nature development - land use - agriculture - coastal management - protection - coastal areas - western scheldt - south-west netherlands
    Het concept wisselpolder gaat uit van een cyclisch opslibben van laaggelegen, ingeklonken binnendijkse gebieden en tegelijkertijd indijken van hooggelegen buitendijkse gebieden en deze zo beschikbaar te stellen voor traditionele landbouw. Het verwachte resultaat is een brede relatief hoog gelegen bufferrand langs estuaria, dat het achterliggende land beter helpt beschermen tegen calamiteiten dan de huidige strategie van steeds verder verhogen van de dijken. Het ontstaan van schorren in de wisselpolder is cruciaal voor het proces van opslibben. Randvoorwaarden die mee helpen te bepalen of een wisselpolder succesvol wordt, zijn geformuleerd op basis van studies aan natuurlijke dijkdoorbraken en doelbewuste ontpoldering. Hoe natuurlijker de regeneratie van schorren in termen van sedimentatie en kolonisatie gebeurt, hoe groter de kans op opslibbing in het gebied. Na kolonisatie door schorplanten zorgt de vegetatie voor sediment invang, dempen ze de golfenergie en vormen een zeer waardevolle habitat.
    Sedimentstrategie voor de ZW Delta: een verkenning van kansen
    Mulder, J. ; Taal, M. ; Tangelder, M. ; Jansen, H.M. ; Henkes, R. ; Werners, S.E. - \ 2012
    Wageningen : IMARES (Rapport / IMARES Wageningen UR C115/12) - 81
    geologische sedimentatie - kustgebieden - kustbeheer - overheidsbeleid - zuidwest-nederland - geological sedimentation - coastal areas - coastal management - government policy - south-west netherlands
    In deze studie worden de ontwikkelingen in de sedimenthuishouding als uitgangspunt beschouwd voor duurzame inrichting van de ZW Delta. Centraal staan de kansen van een sedimentstrategie: het gericht beïnvloeden van de sedimenthuishouding, met het oog op het bereiken van een of meer (beleids)doelen.
    Habitat suitability rules for the shallow coastal zone in The Netherlands
    Wolfshaar, K.E. van de; Glorius, S.T. ; Sluis, M.T. van der - \ 2012
    IJmuiden : IMARES (Report / IMARES Wageningen UR C064/12) - 65
    geologische sedimentatie - kustgebieden - aquatische ecologie - vissen - zandsuppletie - habitats - geological sedimentation - coastal areas - aquatic ecology - fishes - sand suppletion - habitats
    Sand nourishment is an essential part of the long term flood defense strategy of the Dutch coast. A distinction can be made between beach nourishments and underwater nourishments. This report concerns underwater nourishments. Nourishments have ecological consequences that differ between species living in the shallow coastal zone. An additional complication is that the ecosystem in this shallow zone is not well studied because it is too shallow to use a ship, and too deep to walk. Hence, knowledge on abiotic and biotic conditions in which species live is scarce. However, some studies were done in the shallow zone and knowledge on the use of the shallow zone by fish is recently developed in the projects Zandmotor and Building with Nature HK3.8 Smart Nourishments.
    Sustainable development of land reclamations and shorelines full scale experiments as a driver for public - private innovations
    Aarninkhof, S.G.J. ; Allewijn, R. ; Kleij, A.M. ; Stive, M.J.F. ; Baptist, M.J. - \ 2012
    - p. 1 - 12.
    kusten - kustbeheer - geologische sedimentatie - natuurontwikkeling - zandsuppletie - noordzee - coasts - coastal management - geological sedimentation - nature development - sand suppletion - north sea
    With 80% of the world's population living in lowland urban areas by 2050, sea levels gradually rising and societal demands on the quality of living increasing, sustainable development of coastal zones becomes increasingly urgent as well as complex. Modern strategies for the design and implementation of measures for infrastructure development, coastal protection and other functions adopt the concept of Building with Nature to handle these challenges. Recently, two full scale experiments were implemented to assess the benefits of the this approach for coastal development. The Sand Motor pilot project addresses the potential concentrated nourishments on the basis of a 21 million m3 shore nourishment at the Delfland coast in the Netherlands. This unprecedented experiment aims to protect the hinterland from flooding by letting natural processes distribute sand over shoreface, beach and dunes, thus constituting a climate-robust and environmentally friendly way of coastal protection. The second experiment addresses the concept of seabed landscaping in sand extraction sites, which aims to add ecological value to the sand borrow areas after construction. Both pilots have been monitored since their completion in 2010/2011 and will be monitored extensively in the coming years.
    Developing an interactive Tool for evaluating sand nourishment strategies along the Holland coast in perspective of benthos, fish nursery and dune quality
    Baptist, M.J. ; Wolfshaar, K.E. van de; Huisman, B.J.A. ; Groot, A.V. de; Boer, W. de; Ye, Q. - \ 2012
    Den Burg : IMARES (Rapport / IMARES Wageningen UR C083/12) - 38
    kustbeheer - zandsuppletie - versterking - duinen - nadelige gevolgen - geologische sedimentatie - vissen - aquatische ecologie - noordzee - coastal management - sand suppletion - reinforcement - dunes - adverse effects - geological sedimentation - fishes - aquatic ecology - north sea
    Sand nourishments can affect the coastal ecosystem in various ways. Direct effects are the burial of benthic species under a layer of sand. In the direct vicinity, suffocation of benthos can occur due to the settling of a plume of suspended sediment particles. A plume of fine particles may also increase turbidity and thereby affect primary production and the foraging success of filter-feeding benthos and fish. Indirect effects are habitat change, such as altered morphology and sedimentology. It was tested by investigating whether it is possible to optimise nourishment configuration, location and timing, to: - minimise the impact on benthos, - increase nursery area and/or quality, and - enhance dune quality.
    Zandwining en suppleties in de Zuidwestelijke Delta: ecologische vragen vanuit sedimentbeheer in relatie tot beheerdoelen van Rijkswaterstaat
    Tangelder, M. ; Rozemeijer, M.J.C. ; Wijsman, J.W.M. ; Baptist, M.J. - \ 2012
    Yerseke : IMARES (Rapport / IMARES Wageningen UR C160/12) - 45
    kustbeheer - geologische sedimentatie - zandsuppletie - aquatische ecologie - nadelige gevolgen - kustgebieden - coastal management - geological sedimentation - sand suppletion - aquatic ecology - adverse effects - coastal areas
    Dankzij de uitvoering van verschillende onderzoekstrajecten in de Hollandse kust, Zuidwestelijke Delta en Wadden is in de afgelopen jaren meer inzicht ontstaan in de ecologische gevolgen van zowel het suppleren van zand in de kustzone als het winnen van zand van de zeebodem. Onderzoek naar sedimentverplaatsingen heeft met name geleid tot meer inzicht in lokale ecologische effecten. Over effecten op het systeem is minder bekend en dit verdient de aandacht.
    Zandwinning in de Nederlandse kustzone 2013 - 2017 en biologische productie in de westelijke Waddenzee, een modelstudie
    Brinkman, A.G. - \ 2012
    Uimuiden [etc.] : IMARES (Rapport / IMARES Wageningen UR C087/12) - 110
    kustbeheer - geologische sedimentatie - zand - aquatische ecologie - nadelige gevolgen - waddenzee - coastal management - geological sedimentation - sand - aquatic ecology - adverse effects - wadden sea
    Ten behoeve van de kustveiligheid wordt jaarlijks zand gesuppleerd om de basiskustlijn en het kustfundament in stand te houden c.q. te versterken. Verwacht wordt dat er over een periode van 5 jaar in totaal 124 miljoen m3 zand gesuppleerd dient te worden. Het zand hiervoor zal gewonnen worden in een aantal wingebieden langs de Nederlandse kust tussen de -20 m-lijn en de 12 mijlsgrens. De voorgenomen zandwinning voor het Hoogheemraadschap moet plaats vinden in de periode 2013- 2014, die voor Rijkswaterstaat in de periode 2013-2017. Bij de zandwinning komt slib vrij dat ook tot in de Waddenzee verspreid wordt. De centrale vraagstelling voor de westelijke Waddenzee luidt: wat zijn de gevolgen van de voorgenomen zandwinningen door RWS en HHNK voor een aantal ecologische sleutelprocessen in de Waddenzee.
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