The effect of natural sponges as flood prevention in the Geul catchment

Motivation: As the infiltration capacity of the Dutch part played an essential role in decreasing the flood peak during the 2021 flood, only 48 mm of the average 145 mm of precipitation came to runoff. It will be interesting to analyse the runoff of the catchment when this infiltration capacity will be strengthened by the implementation of natural sponges in the area. To investigate this for a whole catchment, hydrological models need to be used. So, this will be a model study. 

Research gap: most of the waterboards and knowledge institutes use distributed models, like wflow_sbm, to model the runoff. The subsurface flows are not well represented in the wflow-sbm model. There are models that are more detailed in the subsurface, like SWAP (Soil Water Atmosphere Plant). Only SWAP is a 1D model that works on a field scale. Secondly, natural sponges that delay the discharge of the Geul are possible disadvantageous. The chance that the discharge wave coincides with the peak discharge on the Meuse can increase. 

Research question: What is the effect of natural sponges on the magnitude and timing of the discharge of the Geul combining the SWAP and wflow_sbm model concepts? 

Methodology:
1) Mimic the soil layers of the "Boven Geul" area with SWAP;
2) Choose the parameters that have the most influence on the runoff in SWAP by doing a sensitivity analysis;
3) Repeat this with wflow_sbm;
4) Tweak the wflow_sbm outcome to the SWAP outcome;
5) Run the tweaked wflow_sbm system with strengthened infiltration capacity scenarios for the whole catchment;
6) Analyse the new timing of the Geul to the Meuse in a Meuse system perspective (do the flood peaks coincide?). 

For more information, please contact: grootjosien@gmail.com