Water managers worldwide use hydrological models to forecast river discharges for flood warnings of spatial development projects. Unfortunately, the models that are used in lowland catchments are often complex and computationally demanding, while simpel models are usually developed for sloping catchments. In this thesis, the most important processes which determine the response of a lowland catchment to rainfall are analysed.
Measurements in the Hupsel Brook catchment (eastern part of The Netherlands) and Cabauw polder (western part) indicate that shallow groundwater causes moist top soils and little water stress for plants, that certain flowroutes (for example through drainpipes or over the land surface) are only used when the catchment is wet enough and that high surface water levels limit groundwater drainage.
These findings contributed to the development of the Wageningen Lowland Runoff Simulator (WALRUS), a new, efficient hydrological model, which can be used by water managers and researchers in lowland catchments worldwide.