Assessment of Runoff Pattern and Relationship to Sediment Yield of Bhagirathi–Alaknanda River Basin Using Geospatial Techniques

Abstract

Erosion has been as a major issue in Bhagirathi and Alaknanda river basins due to high surface runoff. The river basins are located in the Uttarakhand state of India and have a total basin area of 19,066.5 km2. Sediment yield has been estimated and then correlated with the surface runoff using geospatial techniques during the period 2000–2015. Analytic hierarchy process (AHP) has been used to estimate the sediment yield. All required layers for assessment of runoff and sediment yield has been prepared in a geographical information system environment. Tropical Rain Measuring Mission (TRMM) rainfall data (0.25° × 0.25°), Global Land Data Assimilation System (GLDAS) runoff data (0.25° × 0.25°), Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) elevation data (30 m), and Landsat 5 and Landsat 8 satellite images (30 m) have been used to prepare rainfall maps, runoff maps, relief maps, and land use/land cover maps respectively. The study has shown that the sediment yield, as well as runoff, has a non-monotonic trend during 2000 to 2015. The highest runoff has been observed in the year 2013 whereas minimum runoff was in the year 2009. Correspondingly, the highest and lowest sediment yields were observed in the years 2013 and 2009 respectively. The northern part of the catchment was observed to be more vulnerable with respect to high sediment yield as well as runoff. As a whole, both river basins have a strong positive correlation between sediment yield and runoff with R2 values of 0.8. With respect to the findings, it can be concluded that some of the reservoirs for hydropower projects within these river basins may be in danger in the near future due to high sediment yields.