The potential of upstream depressional wetlands in restoring the water system
We are facing more extreme weather events due to climate change, such as floods and droughts, as we have experienced in recent years in Western Europe. Blue-green measures can be implemented to increase the water storage in the landscape and thus to enhance the water availibility.
This study aims to investigate the potential of upstream depressional wetlands (UDWs) to buffer and infiltrate water. They have, due to their topographical position in the landscape, the possibility to retain and infiltrate water and this way recharge groundwater reserves. They are natural depressions in the landscape that were not naturally connected to the watercourse network. These small marshes were often reclaimed centuries ago by connecting them to the watercourse via hand-dug ditches.
Three UDWs in the sandy soils of the Campine region (northern Belgium) have been continuously monitored since February 2020. Two landscape depressions are drained by means of ditches and are intensively used as arable land, the third is moderately drained and has a more extensive grassland management. This monitoring aims to measure the hydrological balance of these systems and consists of measuring the groundwater level (via piezometers in each site), various weather parameters (precipitation, evaporation, etc.) and a measuring channel that measures the drainage outflow in the ditch. In addition, water quality and soil samples were taken to gain a full understanding of the geohydrology of the system. Furthermore, the groundwater flux is continuously monitored with a groundwater sensor.
The first step consists of making a hydrological characterisation of the study sites. In a next step, we will analyse the effects on fluxes using model simulations, followed by validation with independent measurements. Additional input from stakeholders, such as farmers and policy-makers can then be implemented in several scenarios to make it more applicable and set up guidelines for implementation of blue-green measures, such as the implementation of weirs in ditches.