Numerical investigation of depth-dependent roughness and infiltration methods in rainfall-runoff experiments

ABSTRACT The Hydroinformatics Modeling System (HMS) was used to simulate rainfall-runoff experiments to investigate the impact of different slopes and rainfall intensities for traditional and low-impact development (LID) surface conditions. HMS solves the depth-averaged 2D shallow water equations with robust numerical methods. Most importantly, depth-dependent roughness and depth-dependent infiltration methods are implemented and allow the model to simulate a bunch of scenarios. Calibration and validation results are evaluated based on the criteria of the Nash-Sutcliffe Efficiency (NSE) and Standard Deviation Ratio (SDR). Both, the calibration and validation cases achieve very good agreements between computations and measurements with NSE all higher or equal than 0.97 and SDR all smaller or equal 0.17. The results demonstrate the superiority of the depth-dependent infiltration method when compared to a constant infiltration and the necessity of the depth-dependent roughness approach for accuracy and stability reasons. The methods implemented here might also improve other shallow water models.