Data belonging to Kaandorp et al., Transient travel time distributions and age-ranked storage-dis... more Data belonging to Kaandorp et al., Transient travel time distributions and age-ranked storage-discharge relationships of three lowland catchments. Submitted to Water Resources Research, December 2017.
Dit artikel beschrijft de ontwikkeling van de zoetzoutverdeling in het Nederlandse grondwater. De... more Dit artikel beschrijft de ontwikkeling van de zoetzoutverdeling in het Nederlandse grondwater. Deze verdeling is sterk bepaald door de paleogeografische ontwikkeling gedurende het Holoceen en kent een groot langetermijngeheugen. Er worden twee typen grondwatersystemen beschreven: het West-Nederland systeem, waar autonome verzilting en wellen sleutelbegrippen zijn, en het Zeeuwse systeem, waar drie typen zoetwaterlenzen worden besproken. We laten aan de hand van de FRESHEM-Zeeland-resultaten zien dat airborne-elektromagnetische meettechnieken zeer geschikt zijn voor het in beeld brengen van de zoet-zoutverdeling. Vervolgens wordt ingegaan op het modelleren van de initiele zoet-zoutverdeling, waarbij de combinatie van paleomodellering en gebruik van metingen een geschikte methode lijkt. De initiele zoet-zoutverdeling is een belangrijke modelparameter bij het voorspellen van toekomstige veranderingen van zoete grondwatervoorraden als gevolg van ingrepen, klimaatverandering en zeespiege...
Maaiveldafvoer is in Nederland slecht bekend. Om meer grip op dit verschijnsel te krijgen is in 2... more Maaiveldafvoer is in Nederland slecht bekend. Om meer grip op dit verschijnsel te krijgen is in 2014 en 2015 op een aantal percelen nabij Ootmarsum een eerste meetonderzoek uitgevoerd. De uitkomsten zijn meegenomen in een theoretische vervolgstudie omtrent maatgevende afvoeren in het werkgebied van Waterschap Vechtstromen. Dat heeft geresulteerd in een set kaarten die de (theoretische) maaiveldafvoer gebiedsdekkend duiden. Het is de bedoeling om de waarde van deze kaarten (en de gehanteerde methode) te toetsen met aanvullende veldproeven.
For the Province of Zeeland in the Netherlands, a 3D‐model for density‐dependent groundwater flow... more For the Province of Zeeland in the Netherlands, a 3D‐model for density‐dependent groundwater flow and coupled solute transport is developed to assess the impact of sea level rise and changing precipitation and evapotranspiration patterns on the freshening and salinisation processes of shallow groundwater systems. The model is used to determine feasible and robust adaptation or mitigation measures in the water system to secure the vulnerable fresh water resources in this low‐lying coastal zone. We will present the building of the complex 3D numerical model (15 million model cells), and with the focus on the determination of the initial chloride distribution. For this different types of (geophysical) techniques are combined with groundwater sampling data.
In zoute kwelgebieden zijn dunne regenwaterlenzen van groot belang voor de landbouw omdat ze vaak... more In zoute kwelgebieden zijn dunne regenwaterlenzen van groot belang voor de landbouw omdat ze vaak de enige zoetwaterbron zijn en voorkomen dat (te) zout kwelwater de wortelzone bereikt. Veldonderzoek in Zeeland heeft voor het eerst in beeld gebracht hoe deze lenzen er precies uitzien, hoe ze veranderen in de tijd en welke processen daarbij een rol spelen. De lenzen blijken erg kwetsbaar voor klimaatverandering. De opgedane systeemkennis maakt het mogelijk hiervoor mitigerende maatregelen te formuleren.
<p&amp... more <p>Surface runoff is widely recognized as playing an important and unique role in contaminant<br>transport from agricultural fields to the river system. Its quantification however is still<br>underdeveloped, especially in flat areas. Because micro-topography (< 10 cm) likely is an<br>important controlling factor in such landscapes, accurate predictions of the occurrence and<br>quantity of surface runoff are limited by a lack of high-quality data and/or computational power.<br>This project will explore the applicability of both conceptual (fill-and-spill) and state-of-the-art<br>physically based models to estimate surface runoff at the field scale. Laser technology will provide<br>high resolution surface topography data and direct measurements of surface runoff will aid in<br>validating the hydrologic models. The goal of this research is to use the results of the field study to<br>develop an efficient and accurate upscaling scheme, centred around a generic parameterization of<br>micro-topographic variability. This could support decision and policy making and contribute to<br>increasing the water quality of river systems.</p>
<p&amp... more <p>In large parts of Europe, the year 2018 is known as an extremely dry year. In the Netherlands this 2018 drought caused over 1 billion euros of economic damage to different sectors like agriculture, nature, industry, shipping, infrastructure and buildings. A large part of economic damage was due to extreme low groundwater levels and large soil moisture deficits. Many streams stopped flowing since groundwater levels were too low to feed the streams. The extreme low rainfall amount, in combination with above average high potential evaporation rates, caused a precipitation deficit of 300 mm in the growing season, which is normally less than 100 mm. In 2019, the year after, the spatial variability of precipitation in the Netherlands was high with only a precipitation deficit in the growing season of a few tens of millimeters in the low-lying western part of the Netherlands. However, in the higher sandy areas in the south and east part of the Netherlands, the precipitation deficit was again extreme and more than 240 mm. For the higher sandy areas this was the second dry year in a row and the question arose what the effect of two consecutive dry years on the water system was and how fast it may recover.</p><p>This question has been analyzed by applying an integrated nationwide groundwater and surface water model (De Lange et al., 2014). The model results showed that for the higher sandy areas, groundwater levels and stream discharges were even lower in the second than in the first dry year. In addition, the recovery period of the groundwater system after two extremely dry years was examined by simulating ten "normal" years with average precipitation and evaporation patterns following the two extremely dry years. The model results showed a large spatial variation in groundwater level recovery.  In the first recovery year groundwater levels increased for most of the area, except for the higher-lying sandy areas lacking any surface waters (ditches and streams), like the largest Dutch forest area, the Veluwe. In these slow-responding regional recharge areas, groundwater levels are still dropping. For the central part of the Veluwe, this dropping continues until the seventh recovery year.  The model results showed that two consecutive dry years have a large impact on the water system, and that full recovery of groundwater levels and stream discharges may take 2 to 4 years in most of the sandy areas, yet the recovery of the highest parts may take up to 7 to 8 years.</p><p> </p><p>De Lange, W.J., Prinsen, G.F., Hoogewoud, J.C., Veldhuizen, A.A., Verkaik, J., Oude Essink, G.H.P., Van Walsum, P.E.V., Delsman, J.R., Hunink, J.C., Massop, H.Th.L., Kroon T. (2014). An operational, multi-scale, multi-model system for consensus-based, integrated water management and policy analysis: The Netherlands Hydrological Instrument. Accepted for publication in Environmental Modelling & Software</p>
Peat oxidation in deep Dutch polders leads – in addition to subsidence - to the development of ne... more Peat oxidation in deep Dutch polders leads – in addition to subsidence - to the development of new saline boils, enhancing the salinization of these polders. This on-going process is studied in detail in the Middelburg-Tempelpolder. The objective of the study was to get more in-depth knowledge about this process and to assess it for the present situation and for future landscapes (after 10, 50, 100 and 500 years).
Nature area Rammegors, which has recently been transformed from a fresh inner-dyke nature area to... more Nature area Rammegors, which has recently been transformed from a fresh inner-dyke nature area to a salt tidal area. Due to this transformation, salt water is infiltrating in a fresh waterlens. This salinisation process is investigated in more detail by two- and three dimensional models together with mearsurements in the area. Zeeland project FRESHEM has provided detailed isohaline maps of the area and Deltares is making transient isohaline maps based on measurements made by an ERT-cable which is situated in Rammegors. These data has been and will be used to investigate which factors; bathymetry, lithology, tides or regional groundwater flow, will have the largest impact on the salinization process in Rammegors. This investigation shows that discretization size has an influence on the speed and spatial distribution of salt plumes. Lithology has the largest influence on the salinization process, followed by bathymetry. Spring and neap tides do differ from the normal tides situation o...
<p>Innovative, sustainable and cost-effective coastal protection solutions are requ... more <p>Innovative, sustainable and cost-effective coastal protection solutions are required to adapt to environmental change and enhance ecosystem functioning. Managed realignment is an example of an ecosystem engineering coastal management approach motivated by concerns about biological conservation and sea-level rise. It involves relocating the line of defense landward, thereby mimicking what would normally happen with marine environments during a period of sea-level rise. The retreat allows new salt marshes to develop offering a range of ecosystem services. Despite the ongoing execution of managed realignment projects in, amongst others, the UK, Germany, the Netherlands, Belgium and Spain, it remains unclear whether management realignment is able to deliver on the expected socio-economic and environmental benefits.</p> <p>Here we report on the short-term (0-4 years) development of physical and ecological processes of the Perkpolder managed realignment area in the Scheldt estuary, the Netherlands, following tidal restoration in 2015. The overarching goal of the Perkpolder project was to realize 75 hectares of low-dynamic tidal nature contributing to Natura2000 conservation goals for the Western Scheldt estuary as well as serving as a compensation measure for the extension of the navigation channel for the Antwerp harbor.</p> <p>The Perkpolder managed realignment is considered a unique opportunity to monitor and study the biotic and abiotic changes in an area transforming from a freshwater agricultural area to a tidal saline natural area. An interdisciplinary monitoring framework was set up to record the abiotic and biotic developments of the Perkpolder realignment area, particularly focusing on morphological changes, colonization of the new tidal area by benthic macrofauna and vegetation, and its function as foraging area for water birds. Also the groundwater system is studied and its effect on the surrounding agricultural land.</p> <p>A mitigation measure, called ‘SeepCat’, was installed on the border of the new tidal area and the agricultural land to protect the freshwater lens used by farmers for irrigation. The lens was expected to shrink by this local sea level rise. From the groundwater measurements, it was concluded that the SeepCat system was functioning well enough to compensate for the effects of the new tidal area.</p> <p>Using a Delft3D numerical model simulation, it was shown that the design of the morphological template has a large impact on the rates of morphological change. Additionally, the sediment import, estimated from SPM concentration and discharge measurements, varied strongly in time, and sediment was also being exported for a number of tides. Controlled laboratory experiments show that seedlings of pioneer marsh plant species survive best in a well-drained soil without sediment dynamics. Yet, seedlings can tolerate some moderate sediment dynamics. From a benthic community perspective, the development of the managed realignment Perkpolder is encouraging. A biologically active intertidal area has formed within a short time frame. Within 3 years, the benthic macroinfaunal community shows a development towards a community found on natural tidal mudflats and is expected to reach a stable community in years rather than decades. The area is also frequently visited by birds, which forage during low tide and rest on the surrounding dikes during high tide.</p>
Data belonging to Kaandorp et al., Transient travel time distributions and age-ranked storage-dis... more Data belonging to Kaandorp et al., Transient travel time distributions and age-ranked storage-discharge relationships of three lowland catchments. Submitted to Water Resources Research, December 2017.
Dit artikel beschrijft de ontwikkeling van de zoetzoutverdeling in het Nederlandse grondwater. De... more Dit artikel beschrijft de ontwikkeling van de zoetzoutverdeling in het Nederlandse grondwater. Deze verdeling is sterk bepaald door de paleogeografische ontwikkeling gedurende het Holoceen en kent een groot langetermijngeheugen. Er worden twee typen grondwatersystemen beschreven: het West-Nederland systeem, waar autonome verzilting en wellen sleutelbegrippen zijn, en het Zeeuwse systeem, waar drie typen zoetwaterlenzen worden besproken. We laten aan de hand van de FRESHEM-Zeeland-resultaten zien dat airborne-elektromagnetische meettechnieken zeer geschikt zijn voor het in beeld brengen van de zoet-zoutverdeling. Vervolgens wordt ingegaan op het modelleren van de initiele zoet-zoutverdeling, waarbij de combinatie van paleomodellering en gebruik van metingen een geschikte methode lijkt. De initiele zoet-zoutverdeling is een belangrijke modelparameter bij het voorspellen van toekomstige veranderingen van zoete grondwatervoorraden als gevolg van ingrepen, klimaatverandering en zeespiege...
Maaiveldafvoer is in Nederland slecht bekend. Om meer grip op dit verschijnsel te krijgen is in 2... more Maaiveldafvoer is in Nederland slecht bekend. Om meer grip op dit verschijnsel te krijgen is in 2014 en 2015 op een aantal percelen nabij Ootmarsum een eerste meetonderzoek uitgevoerd. De uitkomsten zijn meegenomen in een theoretische vervolgstudie omtrent maatgevende afvoeren in het werkgebied van Waterschap Vechtstromen. Dat heeft geresulteerd in een set kaarten die de (theoretische) maaiveldafvoer gebiedsdekkend duiden. Het is de bedoeling om de waarde van deze kaarten (en de gehanteerde methode) te toetsen met aanvullende veldproeven.
For the Province of Zeeland in the Netherlands, a 3D‐model for density‐dependent groundwater flow... more For the Province of Zeeland in the Netherlands, a 3D‐model for density‐dependent groundwater flow and coupled solute transport is developed to assess the impact of sea level rise and changing precipitation and evapotranspiration patterns on the freshening and salinisation processes of shallow groundwater systems. The model is used to determine feasible and robust adaptation or mitigation measures in the water system to secure the vulnerable fresh water resources in this low‐lying coastal zone. We will present the building of the complex 3D numerical model (15 million model cells), and with the focus on the determination of the initial chloride distribution. For this different types of (geophysical) techniques are combined with groundwater sampling data.
In zoute kwelgebieden zijn dunne regenwaterlenzen van groot belang voor de landbouw omdat ze vaak... more In zoute kwelgebieden zijn dunne regenwaterlenzen van groot belang voor de landbouw omdat ze vaak de enige zoetwaterbron zijn en voorkomen dat (te) zout kwelwater de wortelzone bereikt. Veldonderzoek in Zeeland heeft voor het eerst in beeld gebracht hoe deze lenzen er precies uitzien, hoe ze veranderen in de tijd en welke processen daarbij een rol spelen. De lenzen blijken erg kwetsbaar voor klimaatverandering. De opgedane systeemkennis maakt het mogelijk hiervoor mitigerende maatregelen te formuleren.
<p&amp... more <p>Surface runoff is widely recognized as playing an important and unique role in contaminant<br>transport from agricultural fields to the river system. Its quantification however is still<br>underdeveloped, especially in flat areas. Because micro-topography (< 10 cm) likely is an<br>important controlling factor in such landscapes, accurate predictions of the occurrence and<br>quantity of surface runoff are limited by a lack of high-quality data and/or computational power.<br>This project will explore the applicability of both conceptual (fill-and-spill) and state-of-the-art<br>physically based models to estimate surface runoff at the field scale. Laser technology will provide<br>high resolution surface topography data and direct measurements of surface runoff will aid in<br>validating the hydrologic models. The goal of this research is to use the results of the field study to<br>develop an efficient and accurate upscaling scheme, centred around a generic parameterization of<br>micro-topographic variability. This could support decision and policy making and contribute to<br>increasing the water quality of river systems.</p>
<p&amp... more <p>In large parts of Europe, the year 2018 is known as an extremely dry year. In the Netherlands this 2018 drought caused over 1 billion euros of economic damage to different sectors like agriculture, nature, industry, shipping, infrastructure and buildings. A large part of economic damage was due to extreme low groundwater levels and large soil moisture deficits. Many streams stopped flowing since groundwater levels were too low to feed the streams. The extreme low rainfall amount, in combination with above average high potential evaporation rates, caused a precipitation deficit of 300 mm in the growing season, which is normally less than 100 mm. In 2019, the year after, the spatial variability of precipitation in the Netherlands was high with only a precipitation deficit in the growing season of a few tens of millimeters in the low-lying western part of the Netherlands. However, in the higher sandy areas in the south and east part of the Netherlands, the precipitation deficit was again extreme and more than 240 mm. For the higher sandy areas this was the second dry year in a row and the question arose what the effect of two consecutive dry years on the water system was and how fast it may recover.</p><p>This question has been analyzed by applying an integrated nationwide groundwater and surface water model (De Lange et al., 2014). The model results showed that for the higher sandy areas, groundwater levels and stream discharges were even lower in the second than in the first dry year. In addition, the recovery period of the groundwater system after two extremely dry years was examined by simulating ten "normal" years with average precipitation and evaporation patterns following the two extremely dry years. The model results showed a large spatial variation in groundwater level recovery.  In the first recovery year groundwater levels increased for most of the area, except for the higher-lying sandy areas lacking any surface waters (ditches and streams), like the largest Dutch forest area, the Veluwe. In these slow-responding regional recharge areas, groundwater levels are still dropping. For the central part of the Veluwe, this dropping continues until the seventh recovery year.  The model results showed that two consecutive dry years have a large impact on the water system, and that full recovery of groundwater levels and stream discharges may take 2 to 4 years in most of the sandy areas, yet the recovery of the highest parts may take up to 7 to 8 years.</p><p> </p><p>De Lange, W.J., Prinsen, G.F., Hoogewoud, J.C., Veldhuizen, A.A., Verkaik, J., Oude Essink, G.H.P., Van Walsum, P.E.V., Delsman, J.R., Hunink, J.C., Massop, H.Th.L., Kroon T. (2014). An operational, multi-scale, multi-model system for consensus-based, integrated water management and policy analysis: The Netherlands Hydrological Instrument. Accepted for publication in Environmental Modelling & Software</p>
Peat oxidation in deep Dutch polders leads – in addition to subsidence - to the development of ne... more Peat oxidation in deep Dutch polders leads – in addition to subsidence - to the development of new saline boils, enhancing the salinization of these polders. This on-going process is studied in detail in the Middelburg-Tempelpolder. The objective of the study was to get more in-depth knowledge about this process and to assess it for the present situation and for future landscapes (after 10, 50, 100 and 500 years).
Nature area Rammegors, which has recently been transformed from a fresh inner-dyke nature area to... more Nature area Rammegors, which has recently been transformed from a fresh inner-dyke nature area to a salt tidal area. Due to this transformation, salt water is infiltrating in a fresh waterlens. This salinisation process is investigated in more detail by two- and three dimensional models together with mearsurements in the area. Zeeland project FRESHEM has provided detailed isohaline maps of the area and Deltares is making transient isohaline maps based on measurements made by an ERT-cable which is situated in Rammegors. These data has been and will be used to investigate which factors; bathymetry, lithology, tides or regional groundwater flow, will have the largest impact on the salinization process in Rammegors. This investigation shows that discretization size has an influence on the speed and spatial distribution of salt plumes. Lithology has the largest influence on the salinization process, followed by bathymetry. Spring and neap tides do differ from the normal tides situation o...
<p>Innovative, sustainable and cost-effective coastal protection solutions are requ... more <p>Innovative, sustainable and cost-effective coastal protection solutions are required to adapt to environmental change and enhance ecosystem functioning. Managed realignment is an example of an ecosystem engineering coastal management approach motivated by concerns about biological conservation and sea-level rise. It involves relocating the line of defense landward, thereby mimicking what would normally happen with marine environments during a period of sea-level rise. The retreat allows new salt marshes to develop offering a range of ecosystem services. Despite the ongoing execution of managed realignment projects in, amongst others, the UK, Germany, the Netherlands, Belgium and Spain, it remains unclear whether management realignment is able to deliver on the expected socio-economic and environmental benefits.</p> <p>Here we report on the short-term (0-4 years) development of physical and ecological processes of the Perkpolder managed realignment area in the Scheldt estuary, the Netherlands, following tidal restoration in 2015. The overarching goal of the Perkpolder project was to realize 75 hectares of low-dynamic tidal nature contributing to Natura2000 conservation goals for the Western Scheldt estuary as well as serving as a compensation measure for the extension of the navigation channel for the Antwerp harbor.</p> <p>The Perkpolder managed realignment is considered a unique opportunity to monitor and study the biotic and abiotic changes in an area transforming from a freshwater agricultural area to a tidal saline natural area. An interdisciplinary monitoring framework was set up to record the abiotic and biotic developments of the Perkpolder realignment area, particularly focusing on morphological changes, colonization of the new tidal area by benthic macrofauna and vegetation, and its function as foraging area for water birds. Also the groundwater system is studied and its effect on the surrounding agricultural land.</p> <p>A mitigation measure, called ‘SeepCat’, was installed on the border of the new tidal area and the agricultural land to protect the freshwater lens used by farmers for irrigation. The lens was expected to shrink by this local sea level rise. From the groundwater measurements, it was concluded that the SeepCat system was functioning well enough to compensate for the effects of the new tidal area.</p> <p>Using a Delft3D numerical model simulation, it was shown that the design of the morphological template has a large impact on the rates of morphological change. Additionally, the sediment import, estimated from SPM concentration and discharge measurements, varied strongly in time, and sediment was also being exported for a number of tides. Controlled laboratory experiments show that seedlings of pioneer marsh plant species survive best in a well-drained soil without sediment dynamics. Yet, seedlings can tolerate some moderate sediment dynamics. From a benthic community perspective, the development of the managed realignment Perkpolder is encouraging. A biologically active intertidal area has formed within a short time frame. Within 3 years, the benthic macroinfaunal community shows a development towards a community found on natural tidal mudflats and is expected to reach a stable community in years rather than decades. The area is also frequently visited by birds, which forage during low tide and rest on the surrounding dikes during high tide.</p>
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