Modelling snowmelt in Thiba catchment in central Kenya

Abstract

We established, calibrated, and validated a distributed hydrological model for the Thiba catchment in central Kenya. In the 1990s the catchment experienced a sharp increase in the use of water for agriculture. This study represents the first step in modelling the effect of distributed irrigation activities on the river regime in the catchment. The hydrological processes considered were snowmelt, interception, evapotranspiration, overland flow, channel flow, inter-layer drainage, and lateral saturated flow, which were modelled either by finite difference approximation of partial differential equations or by empirical equations derived from the literature. A digital elevation model of cell size 500 m by 500 m was used. The simulated daily runoff showed fairly good agreement with the observed runoff at 2 out of 3 gauging stations. The discrepancy at the last station may have been due to observation error. We confirmed the model's ability to simulate daily runoff