Hydrological sensitivity of a large Himalayan basin to climate change

Abstract

Abstract:The present study sets out to investigate the sensitivity of water availability to climate change for a large western Himalayan river (the Satluj River basin with an area of 22 275 km 2 and elevation range of 500 to 7000 m), which receives contributions from rain, snow and glacier melt runoff. About 65% of the basin area is covered with snow during winter, which reduces to about 11% after the ablation period. After having calibrated a conceptual hydrological model to provide accurate simulations of observed stream flow, the hydrological response of the basin was simulated using different climatic scenarios over a period of 9 years. Adopted plausible climate scenarios included three temperature scenarios T C 1, T C 2, T C 3°C and four rainfall scenarios (P 10, P 5, P C 5 and P C 10%). The effect of climate change was studied on snowmelt and rainfall contribution runoff, and total stream flow. Under warmer climate, a typical feature of the study basin was found to be reduction in melt from the lower part of the basin owing to a reduction in snow covered area and shortening of the summer melting season, and, in contrast, an increase in the melt from the glacierized part owing to larger melt and an extended ablation period. Thus, on the basin scale, reduction in melt from the lower part was counteracted by the increase from melt from upper part of the basin, resulting in a decrease in the magnitude of change in annual melt runoff. The impact of climate change was found to be more prominent on seasonal rather than annual water availability. Reduction of water availability during the summer period, which contributes about 60% to the annual flow, may have severe implications on the water resources of the region, because demand of water for irrigation, hydropower and other usage is at its peak at this time.

Response of hydrological processes to land‐cover and climate changes in Kejie watershed, south‐west China

“…Dettinger et al (2004) found that mountain snowpack melted earlier after an increase in temperature in California, and the results of Stewart et al (2004) showed that increasing temperatures in North America caused earlier occurrences of spring runoff. The simulation results of Singh and Bengtsson (2004) showed that increasing temperatures caused decreases in streamflow in winter, summer, and autumn; however, streamflow increased in spring in western Himalayan rivers. Chen et al (2006) reported significant and subtle increasing trends and slight decreasing trends in streamflow at different headwaters of the Tarim River when temperature and precipitation increased.…”

“…Given the complexity of hydro-meteorological processes in mountain watersheds, determining impacts of land-cover/climate changes on water sources is a challenge to researchers and policy makers. Important work has been carried out on the impact of climate change (Singh and Bengtsson, 2004) and changes in land cover on the hydrological dynamics of mountain watersheds. Changes in climate and land cover in the Himalayas are predicted to have severe, direct impacts on river flows, natural hazards, the ecosystem, and livelihoods and to have an impact on regional climate, namely, the strength and timing of the Asian monsoon (Xu et al, 2007a).…”

Black soot and the survival of Tibetan glaciers

“…These glaciers act as a water storage tower for South and East Asia, releasing melt water to the Indus, Ganges, Brahmaputra, and other river systems, providing fresh water to more than 1 billion people (1,2). Glacial melt provides up to two-thirds of the summer flow in the Ganges and half or more of the flow in other major rivers (3).…”

Predictability of Western Himalayan river flow: melt seasonal inflow into Bhakra Reservoir in northern India

“…Forecasting seasonal meltwater mean inflows into Bhakra has the potential to improve the operational efficiency of the hydroelectric and irrigation projects. The information about snow accumulation in winter provides a key to spring total inflow with lead times of a few months (Singh and Bengtsson, 2004;Schar et al, 2004;Stewart, 2009). However, because of limited data in this region of rugged topography and poor accessibility, there have been few long lead prediction studies of the Satluj and other Himalayan catchments.…”

“…About 65 % of the Satluj Basin area is covered with snow during winter, and about 12 % of the basin (2700 km 2 ) is covered with permanent snowfields and glaciers (Singh and Bengtsson, 2004). The glacier melt runoff in the months of July, August and September occurs after the contribution of seasonal snowmelt, when glaciers become snow free (Singh and Quick, 1993).…”