Research team

Ecosystem Management

Expertise

Hydrodynamics, sediment transport and morphodynamics in estuaries and rivers: field measurements, GIS and remote sensing, numerical modelling

Effects of El Niño and mangrove deforestation on extreme high water level dynamics in a tropical delta 01/11/2020 - 31/10/2022

Abstract

River deltas are hotspots of human activity, but their vulnerability to flood risks is increasing due to climate warming and worldwide conversion of natural floodplains into human land use (LU). Although previous studies have demonstrated that natural wetlands can play a key role in reducing extreme high water levels on small to intermediate scales (~1 – 10 km²), limited knowledge exists on how wetland conversion to human LU affects amplification of high water levels at the scale of whole deltas (~10² - 10³ km²). This particularly holds true for tropical deltas, where mangrove conversion to aquaculture is widespread and where extreme high water levels are caused by specific climate fluctuations such as El Niño. This project aims to yield a fundamental understanding on how the spatial configuration of mangrove versus aquaculture areas impacts the distribution of high water levels in the Guayas delta (Ecuador), where El Niño is the main driver of extreme high water level events. A combination of field measurements, analysis of existing data and hydrodynamic modelling will be used to reach novel scientific insights on the effects of El Niño and mangrove deforestation on high water levels in a tropical delta. Such knowledge is relevant to support sustainable development of delta societies.

Researcher(s)

Research team(s)

How mutual interactions between tidal marsh plants, waves and sediments, determine nature-based shoreline protection capacity. 01/10/2020 - 30/09/2022

Abstract

Tidal marshes are vegetated areas situated along coasts and tidal rivers, which are regularly inundated by tides. Recent studies have highlighted the important role of tidal marshes in protecting the hinterland from the impact of waves, called 'nature-based shoreline protection'. Plants form a barrier for waves, because they are able to weaken the energy of the waves and they reduce erosion of the soil. During winter, this vegetation typically dies off. However, questions remain on how effective marsh vegetation is for shoreline protection, such as: (1) 'Is the effectiveness of wave and soil erosion reduction different in winter or summer?';(2) 'Are some plant species better than others in reducing waves and erosion?'; (3) 'Are some plant species better in coping with the stress they encounter from wave activity, and does that result in the spatial plant species distribution we see in the field, with some species growing close to the water channel, while others more landward?'. In this project I will address these questions in an integrated way: I will investigate the two-way interactions between waves and plants, how that results in the spatial plant species distribution, and how that spatial plant zonation affects the effectiveness of wave and erosion reduction, and hence the shoreline protection capacity of tidal marshes.

Researcher(s)

Research team(s)

Coastal marsh resilience to sea level rise: a field, flume and modelling study on the role of bio-geomo hic self-organization. 01/01/2020 - 31/12/2023

Abstract

Tidal marshes are valuable coastal ecosystems that are threatened by global climate warming and resulting sea level rise. Whether they drown or continue to exist while sea level rises, depends on the trapping of sediments (sand and mud) that builds up the land surface. The sediment trapping is locally determined by so-called bio-geomo hic interactions between plants, water flow, and landform changes. However, the larger landscape also self-organizes by developing a channel network between vegetation patches, and by transporting the sediment through the channels towards the marsh. We will investigate how the small-scale (m²) bio-geomo hic interactions determine the large-scale (km²) self-organization of tidal marsh landscapes and how this affects their adaptability to sea level rise. The aim of this project is to investigate, for the first time, the impact of specific traits of plant species on the self-organization and capacity of marshes to rise with sea level. We test the hypotheses that (1) different plant species lead to the formation of different self-organized tidal channel networks; and (2) the resulting channel networks determine the efficiency to distribute and trap sediments in response to sea level rise. This will be investigated based on a unique combination of field surveys, scaled lab experiments, and computer simulations.

Researcher(s)

Research team(s)

Quantifying and modelling soil carbon accumulation in mangrove forests in response to sea level rise. 01/11/2019 - 31/10/2023

Abstract

Mangrove forests are coastal wetlands with highly valued functions, including climate regulation by capturing atmospheric CO2 and storing it into soil organic carbon (SOC). Mangroves and their SOC accumulation function are at risk to be lost by sea level rise (SLR) by the end of the 21st century. Mangroves are known to have a certain capacity to adapt to SLR by raising their elevation via sediment and SOC accumulation. But present insights and models, allowing to estimate changes in SOC accumulation rates in response to future SLR scenarios, are poorly developed. Here we will conduct for the first time an integrated field and modelling study on feedbacks between rates of SLR, sediment and SOC accumulation in mangroves. This will be studied in the Guayas river delta in Ecuador. We will test the hypotheses that: (1) the adaptability of mangroves to SLR is governed by the strength of feedbacks between increasing tidal flooding, sediment and SOC accumulation rates; (2) the strength of these feedbacks depends on the location along the land-to-sea gradient within a delta, with mangroves in river-dominated parts of a delta having more capacity to accrete sediments and SOC in balance with SLR; while marine-dominated parts of a delta will be more vulnerable to mangrove drowning by SLR. This project will generate novel scientific insights that will feed the development of an innovative model to simulate how SOC accumulation in mangroves will respond to future SLR.

Researcher(s)

Research team(s)

Tidal marshes: bio-geomorphic self-organization and its implications for resilience to sea level rise and changing sediment supply (TIGER). 01/09/2019 - 31/08/2022

Abstract

Intertidal landscapes are complex environments located between the land and sea, and that are regularly flooded by tides. They provide highly valuable ecosystem services that are threatened by sea level rise and changing sediment supply. Previous studies showed that the small-scale (order of m2) interactions between vegetation dynamics, water flow and sediment transport (so-called bio-geomorphic feedbacks) have a great impact on channel network formation and evolution at the landscape-scale (order of km2). We call this process bio-geomorphic self-organization. The aim of this project is to investigate, for the first time, the impact of plant species traits on biogeomorphic self-organization of intertidal landscapes. More specifically, we hypothesize that (1) different plant species traits lead to the self-organization of different channel network patterns, and (2) the resulting self-organized landscape structures determine the efficiency to distribute and trap sediments on the intertidal floodplain, and hence the resilience (adaptability) of the landscape to sea level rise and decreasing sediment supply. By using a combination of computer model simulations and field observations, we aim at producing new fundamental knowledge on landscape selforganization by bio-geomorphic feedbacks, and its implications for the resilience of intertidal landscapes against environmental changes.

Researcher(s)

Research team(s)

Coastal wetland response to sea level rise: an integrative marsh – mangrove study on soil elevation and soil carbon response. 01/01/2018 - 31/12/2021

Abstract

Coastal wetlands, such as tropical mangrove forests and salt marshes in temperate climates, are unique ecosystems that are often feared to be lost by sea level rise. They can however adapt to a rising sea level to some extent by raising their elevation via sediment accumulation, and they can mitigate climate warming by storing carbon from the atmosphere into their soils. Present insights into the feedbacks between the rates of sea level rise, sediment and carbon accumulation mainly come from studies on marshes in temperate climates, while much less is known for tropical mangroves. Here we will conduct for the first time an integrated field and modelling study on these feedbacks in both mangroves and marshes. We will investigate the hypotheses that: (1) the response of mangroves and marshes to sea level rise is governed by similar feedbacks between the degree of flooding (frequency, duration and depth of tidal flooding), sediment and carbon accumulation rates; (2) the specific strength of these feedbacks, and hence the capacity to accumulate soil carbon and build up of soil elevation with sea level rise, differs between mangroves and marshes due to intrinsic vegetation differences. This project will generate a unique comprehensive field data set which will feed the development of a common model for both mangroves and marshes to simulate expected changes in the rates of sediment and carbon accumulation in response to 21st century scenarios of sea level rise. Based on the model and on global datasets we will provide a new assessment of global changes in carbon accumulation rates and in areas of mangroves and marshes under sea level rates expected for the 21st century.

Researcher(s)

Research team(s)

Global Ecosystem Functioning and Interactions with Global Change. 01/06/2016 - 31/12/2022

Abstract

Ecosystems sustain society by providing natural resources and socio-economic services. Understanding their functioning is thus vital for accurate projections of, among others, global climate and food production and prerequisite to drawing up policies for sustainable management of the planet. This proposal therefore aims at creating the scientific breakthroughs needed to make major advances in understanding of several critical processes that determine the functioning of ecosystems and their interactions with ongoing changes in climate and in resource availabilities. The overarching, long-term goal is to understand ecosystem functioning sufficiently well so that we can, in collaboration with modelling groups, confidently project how ecosystem functioning and services will change in the near and distant future. To pursue this goal, the following four research lines will be prioritized when allocating the Methusalem funding: 1. Obtaining a quantitative understanding of plant carbon allocation to growth, energy production (respiration), and nutrient acquisition (fine roots, root exudation, root symbionts). 2. Improving insight in, and measurements of, biomass production. 3. Better understanding soil carbon dynamics and sequestration. 4. Understanding spatial and temporal variation in carbon and greenhouse gas balances at ecosystem to regional scale and attribution to drivers. In each of these research lines, we aim to understand the mechanisms underlying the global and local spatial variation as well as those underlying the long-term trends and short-term temporal patterns. Focus is on how Global Changes (climate change including extreme events, increasing atmospheric CO2 concentration, nitrogen deposition, etc.) are affecting ecosystem processes and functioning. Many projects will be conducted with the research group of the Methusalem Chair at the University of Hasselt as prioritized partners.

Researcher(s)

Research team(s)

Stability of a tidal marsh under extreme flow conditions: a flume experiment 18/01/2021 - 30/09/2021

Abstract

Coasts and river mouths (estuaries) are increasingly exposed to flood risks due the global and local changes, resulting in sea level rise, increasing magnitude and frequency of storm surges. This increasing flood risk motivates a paradigm shift towards nature-based flood defense, where engineered flood defense structures (like dikes) are supplemented with conservation or creation of wetlands (like tidal marshes) in front of the dikes, which contribute to lower the flood risks. In this EU-INTERREG project, the combined protective function of dikes and natural wetland foreshores in front of dikes are tested under field and laboratory conditions. In the field, controlled dike breach experiments (in the Hedwige-Prosperpolder, Schelde estuary, Belgium & the Netherlands) are conducted to investigate the process of dike breach growth and the interaction with stability of the vegetated marsh foreshore. More specifically within this sub-project, the stability of the marsh soil and vegetation under extreme flow conditions that occur during dike breaches, is tested in a new tidal flume lab facility at the UAntwerp campus (the so-called Mesodrome). Marsh soil monoliths (0.8 m wide x 1.2 m long x 0.4 m deep) containing the marsh vegetation are excavated from the field and placed in the flume, and the responses of the vegetation and soil to extreme flow velocities (up to 2 m/s) are tested.

Researcher(s)

Research team(s)

Bio-geomorphic modelling of the Hedwige-Prosperpolder 01/01/2019 - 31/12/2019

Abstract

This project represents a formal research agreement between UA and on the other hand the client. UA provides the client research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

Research team(s)

How mutual interactions between tidal marsh plants, waves and sediments, determine nature-based shoreline protection capacity. 01/10/2018 - 30/09/2020

Abstract

Tidal marshes are vegetated areas situated along coasts and tidal rivers, which are regularly inundated by tides. Recent studies have highlighted the important role of tidal marshes in protecting the hinterland from the impact of waves, called 'nature-based shoreline protection'. Plants form a barrier for waves, because they are able to weaken the energy of the waves and they reduce erosion of the soil. During winter, this vegetation typically dies off. However, questions remain on how effective marsh vegetation is for shoreline protection, such as: (1) 'Is the effectiveness of wave and soil erosion reduction different in winter or summer?';(2) 'Are some plant species better than others in reducing waves and erosion?'; (3) 'Are some plant species better in coping with the stress they encounter from wave activity, and does that result in the spatial plant species distribution we see in the field, with some species growing close to the water channel, while others more landward?'. In this project I will address these questions in an integrated way: I will investigate the two-way interactions between waves and plants, how that results in the spatial plant species distribution, and how that spatial plant zonation affects the effectiveness of wave and erosion reduction, and hence the shoreline protection capacity of tidal marshes.

Researcher(s)

Research team(s)

Tidal marshes: bio-geomorphic self-organization and its implications for resilience to sea level rise nd changing sediment supply (TIGER). 01/05/2018 - 30/04/2019

Abstract

Intertidal landscapes are complex environments located between land and sea, and that are regularly flooded by tides. They provide highly valuable ecosystem services that are threatened by sea level rise and changing sediment supply. Previous studies showed that the small-scale (order of m2) interactions between vegetation dynamics, water flow and sediment transport (so-called bio-geomorphic feedbacks) have a great impact on channel network formation and evolution at the landscape-scale (order of km2). We call this process bio-geomorphic self-organization. The aim of this project is to investigate, for the first time, the impact of plant species traits on biogeomorphic self-organization of intertidal landscapes. More specifically, we hypothesize that (1) different plant species traits lead to the self-organization of different channel network patterns, and (2) the resulting self-organized landscape structures determine the efficiency to distribute and trap sediments on the intertidal floodplain, and hence the resilience (adaptability) of the landscape to sea level rise and decreasing sediment supply. By using a combination of computer model simulations and field observations, we aim at producing new fundamental knowledge on landscape selforganization by bio-geomorphic feedbacks, and its implications for the resilience of intertidal landscapes against environmental changes.

Researcher(s)

Research team(s)

Support modeling HPP. 01/05/2018 - 31/10/2018

Abstract

This project represents a formal research agreement between UA and on the other hand the client. UA provides the client research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

Research team(s)

Improving groundwater dynamics: a key factor for successful tidal marsh restoration? 01/01/2017 - 31/12/2020

Abstract

In an attempt to restore the water quality in tidal rivers, governments around the world invest a lot of money in reconverting reclaimed agricultural land to tidal marshes. In North-West Europe, more than 140 tidal marshes have already been restored and scientists predict that many more will follow in the coming decades. Nevertheless, there is growing evidence that restored tidal marshes do not contribute to the water quality improving function to the same extent as natural marshes. Researchers found that due to the historical agricultural land use, the soil got compacted, hindering the flow of groundwater in the area. The reduced groundwater flow is thus probably the reason for the observed difference in water quality improvement. Nevertheless, the differences in groundwater dynamics between restored and natural tidal marshes are still poorly understood. In this research, we want to unravel this missing link. We will study the soil properties, the groundwater flow and the nutrient fluxes at the same time in both a natural and a restored marsh along the Scheldt estuary in Belgium. We will use these results to develop a computer model. With this model, we will determine the optimal soil properties of restored marshes in order to optimize their effect on water quality improvement. In cooperation with the water engineering sector, we will translate the optimum to viable design criteria that will ameliorate the water quality improving function of future restored tidal marshes.

Researcher(s)

Research team(s)

Study of the sedimentation and channel formation in a newly created tidal area. 01/01/2017 - 31/12/2018

Abstract

The project aims to study the geomorphological dynamics of the controlled reduced tidal area Bergenmeersen located along the Scheldt river. This area forms together with other areas along the Scheldt part of the Sigmaplan, created by the Flemish Government as a reaction on the floods of 1976. These project areas are water buffers that can accommodate Scheldt water in the event of a storm surge. Due to the combination of these flood control areas with the creation of a controlled reduced tide inside these areas, they play also an important role in restoring the natural habitat in Flanders. The geomorphology of the CRT Bergenmeersen will be measured with a real time kinematic global navigation satellite system. The height measurement of the mudflats and channel beds shall be done with a precise digital level system. This combined method will give a position accuracy of approximately 2 cm with a height accuracy of 1 mm. These data will be processed in specialised software which will result in a three dimensional map of the Bergenmeersen region with his tidal channels. This three dimensional elevation map will be compared with the original topographic measurement before Bergenmeersen was subjected to the tides of the river Scheldt on the 25th of April 2013. By comparing this original elevation model to the new topographic measurements, the amount of sedimentation and erosion of the tidal channels will be established. These results shall be compared with previous measurements done in the pilot project of the Sigmaplan, Lippenbroek. The results of the observations will deliver new information about the formation of tidal channels and the amount and speed of sedimentation and erosion in newly created controlled reduced tidal areas. This information is important in evaluating the success of the development of the natural habitat, also in the other tidal areas that are being created along the River Scheldt within the framework of the Sigmaplan.

Researcher(s)

Research team(s)

Wave impact on tidal flats and marshes in the Lower-Seascheldt estuary 01/11/2015 - 31/10/2017

Abstract

This project aims to quantify the impact of waves on sediment bed stability on a tidal flat and marsh area, the so-called Galgenschoor, in the Scheldt estuary, Belgium. This is done based on field measurements of waves, currents, sedimentation-erosion dynamics and data analysis, with particular emphasis on the quantification of the relative impact of natural wind waves and anthropogenic ship waves, and the relationships between wave loading and sedimentation-erosion dynamics.

Researcher(s)

Research team(s)

Quantifying and modelling the shoreline protection function of marsh vegetation. 01/10/2015 - 28/02/2019

Abstract

This project represents a formal research agreement between UA and on the other hand the client. UA provides the client research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

Research team(s)

Tidal marsh response to sea level rise: interactions between vegetation die-off, flow and sedimentation. 01/10/2015 - 30/09/2017

Abstract

Tidal marsh ecosystems are threatened by global sea level rise, but have a certain ability to adapt by sedimentation. However, in several tidal marsh areas around the world, the sedimentation rate is slower than the rate of sea level rise, through which the tidal marsh is increasingly flooded, causing stress to the marsh vegetation and eventually resulting in large-scale vegetation die-off. In this project we study the impact of vegetation die-off on the tidal flow and sedimentation patterns in a tidal marsh, which are determinant for the (dis)ability of vegetation recovery. The hypothesis is investigated that a critical tipping point exists, i.e. that there is a critical level of vegetation die-off for which the flow and sedimentation rates are so significantly affected that the conditions for vegetation recovery get worse and worse, leading to a potential runaway feedback to permanent marsh loss. This project quantifies the effects of different spatio-temporal patterns of vegetation die-off on the flow and sedimentation rates in a tidal marsh, through a combination of methods, including remote sensing, hydrodynamic modeling, and field experiments. The project will contribute to new knowledge that can improve predictions of the response of tidal marshes to sea level rise.

Researcher(s)

Research team(s)

Data analysis of relations between ship traffic, wind conditions, waves and erosion in intertidal ecosystems in the Scheldt estuary. 01/01/2015 - 31/12/2016

Abstract

Data on wave heights in intertidal ecosystems that result from a past measurement campaign along the Scheldt estuary (Rilland, NL) are analysed in order to determine the wave characteristics of anthropogenic ship-induced waves versus natural wind waves. Wave heights are related to ship characteristics, wind speed and direction, and the currents they produce. Current velocities are connected to the observed erosion, in order to determine the effect of anthropogenic ship traffic versus natural water movements on erosion.

Researcher(s)

Research team(s)

Interactions between sea level rise, vegetation die-off, flow and sedimentation in tidal marshes: an experimental study. 01/10/2014 - 30/09/2018

Abstract

Tidal marsh ecosystems are threatened by global sea level rise, but have a certain ability to adapt by sedimentation. However, in several tidal marsh areas around the world, the sedimentation rate is slower than the rate of sea level rise, through which the tidal marsh is increasingly flooded, causing stress to the marsh vegetation and eventually resulting in large-scale vegetation die-off. In this project we study the impact of vegetation die-off on the tidal flow and sedimentation patterns in a tidal marsh, which are determinant for the (dis)ability of vegetation recovery. The hypothesis is investigated that a critical tipping point exists, i.e. that there is a critical level of vegetation die-off for which the flow and sedimentation rates are so significantly affected that the conditions for vegetation recovery get worse and worse, leading to a potential runaway feedback to permanent marsh loss. This project quantifies the effects of different spatio-temporal patterns of vegetation die-off on the flow and sedimentation rates in a tidal marsh. In this proposal for a BOF/DOCPRO bonus project, this topic is investigated based on field experiments. This is complementary to the original BOF/DOCPRO project (for which the PhD student has obtained an FWO grant), where this topic is investigated by remote sensing and hydrodynamic modeling. The project will contribute to new knowledge that can improve predictions of the response of tidal marshes to sea level rise.

Researcher(s)

Research team(s)

Modelling the geomorphic and ecological evolution of the Hedwige- and Prosperpolder after de-embankment 13/05/2014 - 31/12/2018

Abstract

This project represents a formal research agreement between UA and on the other hand the client. UA provides the client research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

Research team(s)

Tidal marsh response to sea level rise: interactions between vegetation die-off, flow and sedimentation. 01/10/2013 - 30/09/2015

Abstract

Tidal marsh ecosystems are threatened by global sea level rise, but have a certain ability to adapt by sedimentation. However, in several tidal marsh areas around the world, the sedimentation rate is slower than the rate of sea level rise, through which the tidal marsh is increasingly flooded, causing stress to the marsh vegetation and eventually resulting in large-scale vegetation die-off. In this project we study the impact of vegetation die-off on the tidal flow and sedimentation patterns in a tidal marsh, which are determinant for the (dis)ability of vegetation recovery. The hypothesis is investigated that a critical tipping point exists, i.e. that there is a critical level of vegetation die-off for which the flow and sedimentation rates are so significantly affected that the conditions for vegetation recovery get worse and worse, leading to a potential runaway feedback to permanent marsh loss. This project quantifies the effects of different spatio-temporal patterns of vegetation die-off on the flow and sedimentation rates in a tidal marsh, through a combination of methods, including remote sensing, hydrodynamic modeling, and field experiments. The project will contribute to new knowledge that can improve predictions of the response of tidal marshes to sea level rise.

Researcher(s)

Research team(s)

Quantifying threshold conditions for landward erosion and seaward expansion of tidal marsh shorelines. 01/10/2013 - 30/09/2015

Abstract

Tidal marshes, which are vegetated wetlands within larger-scale tidal basins, play a critical role in the physical and biological functioning of that tidal basin. The processes that control the landward erosion and seaward expansion of marsh area are, however, hardly understood. Here we aim at quantifying the hydrodynamic and geomorphic threshold conditions that cause: (1) the start of marsh expansion, by vegetation establishment on an initially bare mudflat. (2) the start of marsh erosion, by cliff formation at an initially gently sloping boundary between a marsh and mudflat.

Researcher(s)

Research team(s)

Spatial pattern formation of water plants: an integrated ecosystem model for the management of low land rivers. 01/01/2013 - 31/12/2016

Abstract

Hydro- and morphodynamic models are an indispensable tool for river managers. Existing models only simulate the interactions between physical processes of water flow, sediment transport and geomorphological changes of the river bed. However, in lowland rivers water plants have a significant impact on these processes. They influence the water quality and flow velocity, can increase flooding risks (because of increased resistance to water flow) and change the bathymetry. Therefore it is necessary to include water plants in a river model. In this research the existing hydrodynamic model STRIVE (STReam and River Ecosystem) will be extended to obtain a tool for management and restoration of rivers with aquatic plants. First a vegetation module is added, which describes the spatial and temporal growth of water plants. Next a transport module is implemented, simulating sedimentation in vegetation patches and erosion adjacent to them. Data gathered in the Nete catchment will be used to calibrate both modules; they include information on vegetation growth, hydrodynamics and river morphology. This extended model will be used to optimize the current mowing management of the Zwarte Nete, reducing flooding risk in combination with maximal conservation of aquatic plant cover. This will result in advice on mowing time and pattern. Next the impact of climate change is investigated, in terms of changing discharges. Model scenarios will estimate the effect of modified discharges on floods.

Researcher(s)

Research team(s)

Submitting a report historical evolution siltation in intertidal areas. 01/01/2013 - 01/07/2014

Abstract

This project represents a formal research agreement between UA and on the other hand WL. UA provides WL research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

Research team(s)

Tidal marsh response to sea level rise: interactions between vegetation die-off, flow and sedimentation. 01/10/2012 - 30/09/2013

Abstract

Tidal marsh ecosystems are threatened by global sea level rise, but have a certain ability to adapt by sedimentation. However, in several tidal marsh areas around the world, the sedimentation rate is slower than the rate of sea level rise, through which the tidal marsh is increasingly flooded, causing stress to the marsh vegetation and eventually resulting in large-scale vegetation die-off. In this project we study the impact of vegetation die-off on the tidal flow and sedimentation patterns in a tidal marsh, which are determinant for the (dis)ability of vegetation recovery. The hypothesis is investigated that a critical tipping point exists, i.e. that there is a critical level of vegetation die-off for which the flow and sedimentation rates are so significantly affected that the conditions for vegetation recovery get worse and worse, leading to a potential runaway feedback to permanent marsh loss. This project quantifies the effects of different spatio-temporal patterns of vegetation die-off on the flow and sedimentation rates in a tidal marsh, through a combination of methods, including remote sensing, hydrodynamic modeling, and field experiments. The project will contribute to new knowledge that can improve predictions of the response of tidal marshes to sea level rise.

Researcher(s)

Research team(s)

Mesodrome. 26/04/2012 - 31/12/2017

Abstract

This project represents a formal research agreement between UA and on the other hand the Flemish Public Service. UA provides the Flemish Public Service research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

Research team(s)

Relative impact of ship-induced waves versus natural water movements on the disturbance of intertidal ecosystems in the Schelde estuary. 01/01/2012 - 31/12/2013

Abstract

The relative impact of ship-induced waves on the intertidal areas of the Schelde estuary is studied in proportion to the impact of natural wind-waves and tidal currents. These effects are measured in relation to different ship properties and on different locations along the estuary in order to relate them to site-specific characteristics of the intertidal flats. The results can be used as a basis for recommendations in order to reduce the impact of shipping on the ecosystem of the Schelde.

Researcher(s)

Research team(s)

Quantifying threshold conditions for landward erosion and seaward expansion of tidal marsh shorelines. 01/10/2011 - 30/09/2013

Abstract

Tidal marshes, which are vegetated wetlands within larger-scale tidal basins, play a critical role in the physical and biological functioning of that tidal basin. The processes that control the landward erosion and seaward expansion of marsh area are, however, hardly understood. Here we aim at quantifying the hydrodynamic and geomorphic threshold conditions that cause: (1) the start of marsh expansion, by vegetation establishment on an initially bare mudflat. (2) the start of marsh erosion, by cliff formation at an initially gently sloping boundary between a marsh and mudflat.

Researcher(s)

Research team(s)

Effect of land reclamation or loss and high water levels in the Scheldt estuary: historical effects (1550-1800) as a reference for current management. 01/01/2011 - 31/12/2012

Abstract

To reduce the risk of flooding along the Schelde estuary, polders are restored to tidal marshes. However there's no empirical data available that describes the relationship between tidal marsh restoration and water level reduction (~ flooding). Therefore, as comparative model, we will study the effects of historical land loss and reclamation along the Westerschelde (1550-1800) (near sea) on the water level of the Zeeschelde (inland), using protists (Diatoms and Testate amoebae).

Researcher(s)

Research team(s)

Quantifying threshold conditions for landward erosion and seaward expansion of tidal marsh shorelines. 01/10/2010 - 30/09/2011

Abstract

Tidal marshes, which are vegetated wetlands within larger-scale tidal basins, play a critical role in the physical and biological functioning of that tidal basin. The processes that control the landward erosion and seaward expansion of marsh area are, however, hardly understood. Here we aim at quantifying the hydrodynamic and geomorphic threshold conditions that cause: (1) the start of marsh expansion, by vegetation establishment on an initially bare mudflat. (2) the start of marsh erosion, by cliff formation at an initially gently sloping boundary between a marsh and mudflat.

Researcher(s)

Research team(s)

Climate change impacts on coastal wetlands. 31/08/2010 - 28/02/2011

Abstract

Coastal wetlands, such as salt marshes and mangroves, are valuable ecosystems that are vulnerable to climate change. Sea level rise and increasing storm frequency and intensity may lead to increased flooding of coastal wetlands, and finally may cause the die-back and erosion of salt marshes or mangroves. In this project we want to study the adaptability of coastal wetlands to increasing sea level and storminess. The dense vegetation of salt marshes or mangroves is able to reduce hydrodynamic forces (tidal currents and waves) and to promote the deposition of sediments. In some places in the world this sediment accretion is enough to overcome the increased flooding by sea level rise and storms, but in other places coastal wetlands are increasingly flooded and finally disappear. In this project we want to identify the critical thresholds that determine the survival or disappearance of coastal wetlands in response to increasing sea level and storminess. These thresholds involve both biotic variables (like vegetation characteristics) and geophysical variables (like suspended sediment availability, tidal range, etc.). The study will be based on a combination of field work (preferably in the Schelde estuary, Belgium, Netherlands), remote sensing, and hydrodynamic modelling.

Researcher(s)

Research team(s)

Climate change impacts on coastal wetlands. 30/08/2010 - 29/06/2013

Abstract

Coastal wetlands, such as salt marshes and mangroves, are valuable ecosystems that are vulnerable to climate change. Sea level rise and increasing storm frequency and intensity may lead to increased flooding of coastal wetlands, and finally may cause the die-back and erosion of salt marshes or mangroves. In this project we want to study the adaptability of coastal wetlands to increasing sea level and storminess. The dense vegetation of salt marshes or mangroves is able to reduce hydrodynamic forces (tidal currents and waves) and to promote the deposition of sediments. In some places in the world this sediment accretion is enough to overcome the increased flooding by sea level rise and storms, but in other places coastal wetlands are increasingly flooded and finally disappear. In this project we want to identify the critical thresholds that determine the survival or disappearance of coastal wetlands in response to increasing sea level and storminess. These thresholds involve both biotic variables (like vegetation characteristics) and geophysical variables (like suspended sediment availability, tidal range, etc.). The study is based on a combination of field work (preferably in the Schelde estuary, Belgium, Netherlands), remote sensing, and hydrodynamic modelling.

Researcher(s)

Research team(s)

Linking optical imaging techniques and 2D-modelling for stuyding spatial heterogenity in vegetated streams and rivers. 01/01/2010 - 31/12/2013

Abstract

The major aim of this project is to develop and apply new 'surface covering' optical measuring techniques with a high spatial and temporal resolution to characterise plant-flow interactions in river ecosystems. This new type of information will be used for the 2D numerical model development within the STRIVE-package. Two individual research fields are defined, based on the scientific sub-discipline and consequent character of measurements.

Researcher(s)

Research team(s)

Interactions between hydrodynamics, geomorphology and ecology in the Schelde estuary 01/12/2009 - 30/11/2013

Abstract

This research project addresses the morphological management of the Schelde estuary, with a focus on the interactions between human interventions, hydrodynamics, geomorphology and ecology. The project aims at quantifying the processes that are responsible for the lateral erosion and accretion of tidal marsh shorelines, with special emphasis on: 1) the relative impact of human factors (ship waves) and natural factors (wind waves etc.) on the erosion and accretion of marsh shorelines. 2) the potential role of vegetation as a sustainable and cost-effective protection against shoreline erosion.

Researcher(s)

Research team(s)

Estuarine morphological management for optimizing flood defence, port accessibility, and ecology 01/12/2009 - 30/11/2013

Abstract

This project investigates the possibilities of morphological management of the Schelde estuary (trough strategic dredging and dumping of sediment) in order to optimize the three main functions of the estuary: 1) The estuary should provide protection against flooding of the densely populated area bordering the estuary. The morphological modifications should lead to attenuation of the landward propagation of tidal waves, storm surges, and sea level rise, and hence should contribute to protection against flooding. 2) The estuary should provide access for sea ships to the port of Antwerp. The morphological modifications should result in concentration of tidal currents towards the shipping channels in order to maximize the self-eroding capacity of the channels. 3) The estuary hosts European protected ecosystems. The morphological modifications should guarantee the variation of estuarine habitats. This is studied by coupling of hydrodynamic, morphodynamic and ecological modelling.

Researcher(s)

Research team(s)

Research into the effects of the Sigma plan, dredging and port expansion in the Scheldt on the environment. 12/10/2009 - 11/01/2011

Abstract

The Schelde is an estuary with many functions: apart from its important ecological function (e.g., as breeding and foraging area for fish, shellfish, birds, etc), the Schelde is an important shipping route (e.g., to the harbour of Antwerp) and densely populated areas along the Schelde need to be protected against storm floods (e.g., inundations 1953, 1976, etc). Sustainable management of the Schelde estuary is only possible when these functions are well balanced. In this project we study the effects of human interventions, such as the construction of controlled inundation areas, dredging and harbour extension, on the natural environment of the Zeeschelde (=Flemish part of Schelde estuary).The current project investigates the sedimentation/erosion processes in a recently constructed inundation area (Lippenbroek, Hamme, Belgium).

Researcher(s)

Research team(s)

Macrophyte patches as biogeochemical hotspots: impact on river water quality? 01/10/2009 - 30/09/2011

Abstract

Macrophyte patches as biogeochemical hotspots: impact on river water quality? 1. Problem Macrophytes play an important role in the structural biodiversity in aquatic ecosystems. Being primary producers, they are a matter of life and death for many organisms. Even on a ecosystem level, they take a central role, but the processes here involved are not yet well known. Though, a good knowledge is crucial to be able to take correct management decisions concerning the improvement of our fresh water ecosystems. On top of this, the presence of macrophytes has an even greater influence on the hydraulics. Macrophytes act as ecological engineers and have therefore a direct influence on stream velocity patterns and on sedimentation and erosion patterns. Changes in these patterns have immediate consequences on biodiversity and geomorphology. 2. Objectives I want to test the main concept of macrophytes being biogeochemical hotspots. After all, there are strong indications that the processes in the sediments underneath macrophyte patches can have greater impact on the water quality than the typically studied pelagic processes. To test this hypothesis, three questions are postulated: 1) Are macrophyte patches biogeochemical hotspots and at what quantity? 2) Which is the maximal length and width a patch can have under certain circumstances? 3) What is theoretically the maximal surface patches can have in a river stretch, given certain circumstances (and what is the total effect of these patches on the water quality, regarding question 1)? 3. Methodology Question 1) will be answered by gathering field data. The organic material from selected patches will be characterized and processes such as denitrification and silica transformation are followed up. All these data will be merged with patterns of stream velocity and sedimentation and erosion in and around the patches. Afterwards, results are analyzed with a diagenetic model and statistically tested. Question 2) will be answered by placing in situ flumes around patches in rivers. In these flumes, the patch growth limiting factors such as stream velocity and erosion-sedimentation will be quantified. Additionally, a great number of patches throughout the country will be measured to verify field flume data. Question 3) will be answered with the Delft-3D model. Data from question 1) will calibrate the model, data from question 2) will validate the model. With this model, I want to estimate the impact of macrophyte patches on the water quality of larger parts of rivers (e.g. 100-1000 m).

Researcher(s)

Research team(s)

Drowned but not deserted. Interactions between social and ecological resilience of estuarine landscapes after flooding. Test-case: the Waasland polders on the west-bank of the river Scheldt (15th-18th centuries) 01/07/2009 - 31/12/2013

Abstract

Estuarine landscapes are very dynamic ecosystems which makes it very difficult to model social and ecological adaptations - resilience - after catastrophic inundations. In this research project the evolution of tidal channels after historical inundations and the human re-occupation of flooded areas in the late medieval and early modern Western Scheldt estuary are used to enhance our knowledge of the long-term interactions between ecological and social resilience.

Researcher(s)

Research team(s)

Unravelling the nebkha-ecosystem as a potential tool against desertification. 01/01/2009 - 31/12/2012

Abstract

The overall goal of this project is twofold: to investigate how nebkha landscapes are formed and maintained, and to test whether the presence of nebkhas in the landscape increases the reistance and resilience against climate change (aridification). To this end, the interactions between nebkha plants, wind, water and sediment are modelled first at the scale of the individual nebkha, and subsequently for the nebkha landscape as a whole.

Researcher(s)

Research team(s)

Effect of land reclamation or loss and high water levels in the Scheldt estuary: historical effects (1550-1800) as a reference for current management. 01/01/2009 - 31/12/2010

Abstract

To reduce the risk of flooding along the Schelde estuary, polders are restored to tidal marshes. However there's no empirical data available that describes the relationship between tidal marsh restoration and water level reduction (~ flooding). Therefore, as comparative model, we will study the effects of historical land loss and reclamation along the Westerschelde (1550-1800) (near sea) on the water level of the Zeeschelde (inland), using protists (Diatoms and Testate amoebae)

Researcher(s)

Research team(s)

Interactions between land reclamation or loss, and water level changes along the Schelde estuary. 01/01/2008 - 31/12/2008

Abstract

Sea level rise threatens human occupation along estuaries. Sedimentation and embankment of intertidal areas (tidal flats and marshes), which form natural ecosystems along estuaries, reduces the volume of estuaries, which may contribute to additional water level changes. This is studied in the Schelde estuary, through reconstruction of the impact of historical land reclamation and loss in the seaward part of the estuary (Westerschelde), on water level changes in the more inland part of the estuary (Zeeschelde). Historical water level changes are reconstructed by (paleo-)ecological study of protist communities (diatoms, testate amoebae) in tidal marshes.

Researcher(s)

Research team(s)

Macrophyte patches as biogeochemical hotspots: impact on river water quality? 01/10/2007 - 30/09/2009

Abstract

Macrophyte patches as biogeochemical hotspots: impact on river water quality? 1. Problem Macrophytes play an important role in the structural biodiversity in aquatic ecosystems. Being primary producers, they are a matter of life and death for many organisms. Even on a ecosystem level, they take a central role, but the processes here involved are not yet well known. Though, a good knowledge is crucial to be able to take correct management decisions concerning the improvement of our fresh water ecosystems. On top of this, the presence of macrophytes has an even greater influence on the hydraulics. Macrophytes act as ecological engineers and have therefore a direct influence on stream velocity patterns and on sedimentation and erosion patterns. Changes in these patterns have immediate consequences on biodiversity and geomorphology. 2. Objectives I want to test the main concept of macrophytes being biogeochemical hotspots. After all, there are strong indications that the processes in the sediments underneath macrophyte patches can have greater impact on the water quality than the typically studied pelagic processes. To test this hypothesis, three questions are postulated: 1) Are macrophyte patches biogeochemical hotspots and at what quantity? 2) Which is the maximal length and width a patch can have under certain circumstances? 3) What is theoretically the maximal surface patches can have in a river stretch, given certain circumstances (and what is the total effect of these patches on the water quality, regarding question 1)? 3. Methodology Question 1) will be answered by gathering field data. The organic material from selected patches will be characterized and processes such as denitrification and silica transformation are followed up. All these data will be merged with patterns of stream velocity and sedimentation and erosion in and around the patches. Afterwards, results are analyzed with a diagenetic model and statistically tested. Question 2) will be answered by placing in situ flumes around patches in rivers. In these flumes, the patch growth limiting factors such as stream velocity and erosion-sedimentation will be quantified. Additionally, a great number of patches throughout the country will be measured to verify field flume data. Question 3) will be answered with the Delft-3D model. Data from question 1) will calibrate the model, data from question 2) will validate the model. With this model, I want to estimate the impact of macrophyte patches on the water quality of larger parts of rivers (e.g. 100-1000 m).

Researcher(s)

Research team(s)

Development and geometric properties of tidal channel networks: implications for the creation of new tidal areas. 01/10/2006 - 31/12/2008

Abstract

During the last decennia, many natural tidal areas (tidal marshes, tidal flats) have been lost, e.g. by dike building along coasts and estuaries. Recently, embanked areas (polders) are set back to tidal influence, in order to restore water storage and natural habitat. The succes of these projects strongly depends on the development of tidal channels, because these channels act as transport paths of water, sediments and nutrients. In this project we examine (1) the geometric properties of tidal channel networks in existing tidal areas, (2) the development of tidal channel networks in a newly created tidal area, and (3) the role of vegetation for channel development. This research is conducted in the Schelde estuary (Belgium, SW Netherlands).

Researcher(s)

Research team(s)

Impact of fast and slow climate change on biodiversity and landscape stability: study of the Late-Glacial and Early-Holocene as a reference for the present-day climate change. 01/07/2006 - 31/12/2010

Abstract

Recent research predicts that the present-day climate change threatens the biodiversity and landscape stability on earth. These predictions are, however, difficult to test. As a reference for the present-day climate change, we study in this project the impact of fast and slow climate changes, which happened during the past, on biodiversity and landscape stability. We study this, using alluvial deposits in Flanders and pollen preserved in these sediments. Special attention is paid to the interactions between vegetation and landscape changes in response to climate change.

Researcher(s)

Research team(s)