Bro – Model Groundwater Mirror Depth (WDM)

This BRO registration object, the ‘Model Groundwater Depth’, is land cover and covers the unpaved, non-built part of the Netherlands. The groundwater depth model is based on measured groundwater depths and area-decking auxiliary information such as ground level height models. Various statistically calculated characteristics of the dynamics (seasonal fluctuation) of groundwater depth in the Netherlands are included. The level of the (freatic) groundwater mirror is intended here in relation to ground level and not to a fixed reference level (usually NAP). We are talking about a model of groundwater depth because it concerns area-covering predictions (interpolations) calculated using statistical methods. For this purpose, observed groundwater mirror depths and related information from different data sources have been used. The main dynamic characteristics are the average highest (smallest depth) and the average lowest groundwater level (largest depth) and the spring groundwater level (GHG, GLG and GVG). These data are again used for a classification in groundwater stairs (Gt’s) as we know them in the Netherlands and were included in previous soil maps. The groundwater stairs are now included in this dataset. The accuracy of the groundwater depth characteristics is also part of the model, in the form of a large number of (300 or more) realisations (drawings) from the probability distributions of these characteristics. By including realisations (drawings) from the probability distribution in the model, the BRO user of the groundwater depth model does not have to make assumptions about the shape of the probability distribution.