A conceptual model for simulating streamflow in a changing snow-covered catchment: application to the data-sparse upper Brahmaputra River basin

Understanding the hydrological processes in the Tibetan Plateau (TP) is increasingly important as the snow resources feed the demand for freshwater for a vast downstream population. Given the limited information available, the task of formulating a hydrological model that characterizes future streamflow at downstream locations is challenging. A flexible conceptual hydrological model is proposed relating snow cover fraction (SCF) and snow water equivalent (SWE) based on remote sensing data, with the aim of characterising flow in the region into the future where temperature profiles will be considerably warmer than they are at present. The model's novelty lies in its ability to simulate dynamically varying SCF, SWE and streamflow using limited available data. Results show the Nash-Sutcliffe efficiency values of modelled SCF, SWE and streamflow are 0.82, 0.66 and 0.75, respectively, in the calibration period (1981 to 1992), whereas they are 0.78, 0.56 and 0.70, respectively, in the validation period (1993 to 2000).