Investigating the effects of blue-green measures for adaptation to droughts at the catchment scale

Recent dry spells in Flanders have triggered an interest on relevant adaptation strategies. Those largely aim at managing water resources during the wet periods of the year in order to enhance the water availability during meteorologically dry periods (or else periods with insufficient rainfall/increased evapotranspiration). Nowadays, blue-green measures for alleviating the impacts of meteorological droughts are receiving increasingly more attention. Examples of such measures in the rural environment of Flanders could, amongst others, involve the restoration of former upstream depressional wetlands and the management of agricultural drainage systems. Those would aim at slowing down runoff and enhancing the potential of water to infiltrate into the soil, feed the groundwater and remain stored in the aquifers.

While in situ investigations and field scale models can already give a valuable image on the potential effects of blue-green measures locally, their effect at the scale of the hydrological catchment is also of great interest. In this frame, a spatially-distributed hydrological model is used. The model is largely based on the AquaCrop model structure for simulating the soil water and a simple 2D groundwater model for the aquifers. It encompasses processes like evapotranspiration, infiltration, groundwater recharge and runoff into the rivers. The large majority of model parameters are retrieved from publicly available databases. The first study case is the Kleine Nete catchment found in the northeast of Flanders. The model accuracy is evaluated against river flow and groundwater level measurements, preliminary results on the hydrological impact of blue-green measures are shared and the task challenges are outlined.