A watershed runoff yield model based on Erlang distribution water storage capacity curve

A storage capacity curve reflects the spatial heterogeneity in water deficiency within a basin and is used for computing the production of watershed runoff. This study analyzed the spatial distributions of watershed storage capacity for several typical basins. The Erlang distribution was shown to have the best fit to the watershed storage capacity curves, which was then adopted to derive the production of runoff in the studied watersheds. This study proposes a novel watershed runoff yield model with increased adaptability based on the Erlang distribution storage capacity curve; hence, the model should be better able to represent the actual runoff yield process in a basin. The proposed watershed runoff yield model generated more accurate simulations compared to those of the Xin'anjiang model. In addition, the parameters of the proposed runoff yield model can be estimated from basin topography and soil type data, thereby providing a feasible approach for the calculation of runoff yield in data-scarce areas.