Model data underlying the publication: Drought mitigation as a driver of flood risk: Assessing the trade-offs induced by Natural Water Retention Measures

The aim of this study is understand the effects of Natural Water Retention Measures (NWRM) on flood risk in shallow groundwater environments. These were assessed by simulating design storm events in the Chaamse beken catchment, North Brabant, The Netherlands using a sequentially coupled subssurface-subsurface modeling approach. It consists of a dynamically coupled groundwater component (MODFLOW6 model) and a component representing the unsaturated zones (MetaSWAP), which provides input to a hydrodynamic surface water model (Delft3D 1D2D FM). The MODFLOW-MetaSWAP model is based on the regional groundwater model of North Brabant, provided by the Brabantse Delta Water Authority, and was refined from the original 250x250m to a 25x25m grid. The surface water model consists of a Delft3D 1D2D FM hydrodynamic model that consists of a 1D waterway network (including drainage ditches) coupled dynamically to a 2D catchment grid of 25x25m resolution. The stream network was generated based on the Dutch database for surface water systems HyDAMO (NHI, 2024) and the drainage ditches were added manually based on the drainage network of North Brabant. Both datasets were provided by the Brabantse Delta Water Authority. The 2D grid was generated based on the Dutch national Digital Terrain Model (AHN, 2024). The outputs are gridded groundwater levels and fluxes (IDF, HED, and CBC files) from the subsurface flow model, and gridded water depth, volume and flow velocity (NetCDF files) from the surface water model, and are provided in this dataset. These include a) the long-term mean high (MHG) and mean low (MLG) groundwater levels of the long-term simulation of the baseline period (1996-2004), as well as a reference case and a drought mitigation scenario under a future climate scenario WH2050 (van den Hurk et al., 2014), b) the annual high (HG3) and low (LG3) groundwater levels used to calculate the long-term means, c) the groundwater levels of a specified day representative of the long-term simulation representative of MHG (January 2002), d) the groundwater fluxes to the surface level and stream network, e) the gridded final simulation time step outputs at point locations and maxima for water depth and volume from the surface water model. The model configuration files, as well as output files exceeding 5GB, including hourly gridded groundwater heads and surface water outputs of the rainfall events, can be provided by the authors upon request.