A mathematical model for calculating river hydrographs using high resolution digital elevation models

Abstract

Prediction of floods is important to prevent damage to human lives, build- ings or infrastructure, and we have developed a simulation model to address this. The model is a so-called distributed rainfall-runoff model, which accounts for spatial variations within the watershed; it is based on a distributed version of the time-area method (Clark, 1945). Travel times are calculated by assuming that the flow can be modelled as creeping flow, and the resulting velocity field is used to solve the so-called time-of-flight/Eikonal equation. Both topographical and heterogeneous properties can be accounted for by the model, which ideally can be used for both gauged and ungauged watersheds after calibration. An automatic watershed delineation algorithm has been implemented to delineate the river s watershed using the D8 Algorithm (O Callaghan and Mark, 1984). To test our model, we create artificial rainfalls, and calculate the hydrograph re- sponse at the watershed outlet. The model works well given the simplifications, and is a framework which can be expanded upon and made more complex.