During my internship at waterboard Rijn en IJssel (WRIJ) the coupling of Wageningen Lowland Runoff Simulator (WALRUS) to a 1D open water model (SOBEK) for the Berkel catchment was studied.
Coupling WALRUS to SOBEK
Supervisors: Paul Torfs (WUR), Gert van den Houten (Waterschap Rijn en IJssel)
WALRUS and SOBEK need to be coupled. Therefore we wanted to see which variables were best available and most important for hydrologic analysis, hydraulic analysis and coupling between these both analysis. WALRUS was recently developed and has some advantages compared to existing lumped rainfall-runoff models. We tested WALRUS for three locations within the Berkel catchment: 1) steep sloping area of Lutum; 2) slightly sloping area of Stadtlohn and; 3) the flat area of Waterleiding. WALRUS performed well with an average Nash-Sutcliffe efficiency of 0.79. A 1D-SOBEK model of the Dutch part of the Berkel catchment is made by WRIJ and for the German part of the Berkel catchment a new 1D schematisation was added. The simulated discharge output of WALRUS was used as input for the SOBEK model. The hydraulic routing component in SOBEK provides a phase shifting of the discharge. Generated parameter sets have a major influence on the validation of the discharge (included the limitations of WALRUS) in SOBEK. The coupling of WALRUS and SOBEK can be used as early warning tool for the prediction of floods and drought. However, further investigation is needed in the working of especially WALRUS in other large catchments.