A simplified model for estimating surface runoff hydrographs at watershed scale

A simplified model for estimating the hydrological response to rainfall events at basin scale is investigated in this study. It involves an abstraction of the real basin geometry based on networks of planes and channels and three semi-analytical components that give the expected areal-average infiltration rate at field-scale, the surface runoff hydrograph as lateral inflow into the channel network, and the water flow routing through the channel network. The model was earlier tested by comparison with Monte Carlo simulations that relied on a detailed representation of spatial variation of excess rainfall and numerical solutions of water routing through planes and channels. The model required a low computational effort that makes it suitable for application at all levels of spatial discretisation. A sensitivity analysis of model response to the complexity of the networks of planes and channels, which consequently influences the computational effort, is presented.