| Popis: |
Snow and glacial melt runoff are the major sources of water contribution from the high mountainous terrain of Indus river upstream of the Tarbela reservoir. A reliable forecast of seasonal water availability for the Kharif cropping season (April–September) can pave the way towards the better water management and subsequently boost the agro-economy of Pakistan. The use of degree-day models in conjunction with the satellite based remote sensing data for the forecasting of seasonal snow and ice melt runoff has proved to be a suitable approach for the data scarce regions. In the present research, Snowmelt Runoff Model (SRM) has not only been enhanced by incorporating the “glacier (G)” component but also applied for the forecast of seasonal water availability from the Upper Indus Basin (UIB). Excel based SRM + G takes into account of separate degree-day factors for snow and ice melt processes. The UIB has been divided into Upper and Lower part because of the different climatic conditions in the Tibetan plateau. The application of seasonal scenario based approach proved to be very adequate for long term water availability forecast. The comparison between different models of operational seasonal forecasts for the UIB for the period in consideration show that SRM + G tends to slightly underestimate the flow volume on average by about 2 % with an overall mean absolute error MAE of 9.6 %, while the two other approaches overestimate the Kharif flow volume on average by about 6 %. More important, the standard deviation of SRM + G forecast errors is 5.7 % only, which is an important indicator for the forecasting skill. |
