Modelling the variability of hillslope drainage using grid-based hillslope width function estimation algorithm

Abstract

Due to the lack of observed groundwater table data and micro-scale topography of the hillslopes constituting a watershed, quantification of subsurface flow using the existing models becomes very difficult. In this context, a low dimensional hillslope storage dynamic model has been developed in this study to represent the physical behaviour of the watershed at the hillslope-scale. The topographic control of the watershed has been described in terms of the hillslope width function (HWF) involving the D8 algorithm-based stream network delineation. Subsequently, to simplify the complex spatial variability of HWF, the distribution functions of exponential, Fourier and Gaussian are fitted and their implications on the variability of the subsurface drainage are quantified in a real Indian watershed. The results reveal that the Gaussian distribution function estimates the subsurface flow very well as compared to the other functions.