1. Components of Himalayan River Flows in a Changing Climate.
- Author
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Chandel, Vikram S. and Ghosh, Subimal
- Subjects
STREAMFLOW ,CLIMATE change ,ATMOSPHERIC models ,GLACIERS ,SNOWMELT ,GLACIAL melting - Abstract
Assessment of the response of the Himalayan river flows to climate change is complex due to multiple contributors: rainfall, snowmelt, and glacier‐melt. The number of studies is limited in this direction due to lack of data availability as well as non‐availability of models considering all the above‐mentioned components. As for example, the state‐of‐the‐art variable infiltration capacity (VIC) model does not account for the glacier melt. Here we integrate a glacier‐melt model with VIC and validate the model output with observed streamflow in five river basins in the Himalayas, at daily scale. Our model simulates the streamflow with Nash‐Sutcliffe estimates greater than 0.65 in all basins. The sensitivity analysis shows that the contribution from snowmelt decreases substantially in all the five basins with highest decrease of 36% in Dudh Kosi (DK), in a warm and dry scenario. The glacier‐melt increases (15%–70%) in a warmer environment with its present volume, but decreases (3%–38%) substantially, when the volumes are reduced to half. However, such a decrease is found to be compensated by increased precipitation in a wetter scenario with a net increase of 3%–13%. Climate model simulations show a decrease in the spring onset times for Sutlej basin while increase for DK basin for both RCP4.5 and RCP8.5 scenarios. Sutlej and Arun basins show decreases of more than 6 days in the center of volume of streamflow, which suggests that there will be increased flows in the early part of year and reduced flows later in the year. Plain Language Summary: Water is one of the resources essential for our survival. Climate change impacts water resources globally, and the impacts are adverse in regions which rely on water from snowpacks and glaciers. The Himalayas is the most magnificent mountain range and has vast reserves of ice and snow. The climate change has affected the Himalayas and reduced storages of ice and snow; lesser snowfall and more melt are evident across the mountain range. These changes affect about a billion people that reside in the basins of the Indus, Ganges, and Brahmaputra rivers. The water in these rivers is contributed by rainfall, snowmelt and glacier‐melt. Here, we studied changes in streamflow and its components in the Central Himalayas with changing precipitation and temperature scenarios. We found that in warming climate, snowmelt will reduce substantially, and glacier melt will increase initially, but with significantly reduced volumes in the latter end of the century, it will start to decrease. However, in a wetter scenario, increased precipitation may compensate for such a decrease. The changes in streamflow in early spring and autumn vary from basin to basin in the Himalayas. Key Points: Integration of temperature index glacier model with state of art variable infiltration capacity model to consider melts from clean and debris covered glaciersThe rainfall dominates the Central Himalayan water resources, and the streamflow is highly sensitive to precipitation changesSutlej basin shows decrease in the sprint onset times while Dudh Kosi shows increases for RCP 4.5 and 8.5 scenarios [ABSTRACT FROM AUTHOR]
- Published
- 2021
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