Comparative evaluation of three infiltration models for runoff and erosion prediction in the Loess Plateau region of China

Loess Plateau is known for its high rate of soil erosion. Infiltration models are needed to simulate runoff hydrograph for erosion prediction. Rainfall-runoff data at 1-min interval for 33 plot-events in Tuanshangou catchment were used to evaluate three infiltration models: constant infiltration (CI) rate, spatially variable infiltration (VI) rate, and Green–Ampt (GA). Each of the three models has three parameters. The three models performed similarly when calibrated for individual storms with a Nash–Sutcliffe coefficient (NSC) of efficiency of around 0.76, with better performance for large storm events. For all three models, the total runoff amount is well simulated while the modelled peak runoff rate is systematically smaller by about 30%. The variation in the initial infiltration amount is smaller than that in other infiltration parameters. For ungauged events, averaged parameter values were used to predict runoff hydrographs, and the results showed a decrease in model performance with the average NSC reduced to 0.47. One advantage in using the spatially VI model is that the simulated runoff is least sensitive to changes in model parameters compared with the other two models, as a 10% variation in parameter values would lead to 5% variations on average in the simulated runoff for VI, while around 8.6% for the other two.