Dewatering depth current climate

The drainage depth map with the Average Highest Groundwater Level (GHG) calculated by the National Water Model has been refined with the height map at 0.25 m2 (AHN3). The maps thus present the groundwater level in meters below ground level, scaled back to 0.25m2 for the current climate (2019). The GHG are currently calculated for the KNMI scenarios using the National Water Model (www.nhi.nu). The calculation cell size is 250*250m; the representation concerns the groundwater levels relative to an average ground level height for these calculation cells. In the first step, the GHG of the NWM is refined, so that the soil storage can be determined at a higher level of detail, and the dewatering depth map is made (GHG minus ground level). This is done via: 1) Linear interpolation of the calculated groundwater level between the cells. 2) The ground level of the AHN3 (ground level) can be used for refining groundwater levels relative to ground level