Bharat R. Sharma,Cai Xueliang,Devaraj de Condappa, International Water Management Institute, New Delhi-India Office, b.sharma@cgiar.org
Abstract
Annual flow in the Indus is 120-230 km3 (1957-97) with only about 10% net discharge to the sea, and with glacier melt providing stream flow in the upper basin. Our analysis using Water Evaluation and Allocation Policies (WEAP) modelling with a special sub-routine for glacial and snow melt showed that the average contribution from glacier melt is 47.2 km3 /year (64% of total) at Tarbela dam and 44.2 km3 /year (54.1%) at Sukkur barrage in Pakistan. The simulations showed that an increase of 1°C to 3°C over the next 20 years may change the annual flow by +9 to +31% at Tarbela dam and +10 to +34% at the Sukkur barrage. This is likely to have very serious implications for the water resources availability and use in the short and long term. In the short and medium term large investments may be made in creation of water infrastructure to avoid flooding in the upper reaches and the plains. In the medium to long term, water efficient cropping and irrigation methods, and possible reduction in the irrigated areas in the basin shall be required.
Keywords: Climate change, Indus basin, WEAP modelling