Water discharge and suspended sediment dynamics in the Chandra River, Western Himalaya

Abstract

Glacier systems are important components of the hydrological cycle and a major source of meltwater and sediment flux that controls the river ecology, water quality, and hydropower generation in the Indian Himalayan Region (IHR). Thus, understanding short- and long-term changes in water and suspended sediment (SS) dynamics is crucial in highly sensitive pro-glacial Himalayan Rivers. In the present study, the Chandra River basin in Western Himalaya was chosen to study river discharge, SS transport dynamics, physical erosion rate, and their governing factors for the 2017 melting season (May-September). The daily mean water discharge and SS concentration in the Chandra River was 260.7 m sup(3) s sup(-1) and 775.5 mgL sup(-1) with maximum discharge and SS flux in the month of July. The air temperature showed significant relationship with the river discharge (R sup(2) = 0.67; n = 156; p less than 0.001), which in turn controlled the SS export in the basin (R sup(2) = 0.86; n = 130; p less than 0.001). An anticlockwise sediment-discharge hysteresis during peak flow conditions suggest exhausted sediments or large distance of sediment transport (greater than 100 km) from the upper glacierized region to the end of the basin. Statistical analysis of SS particle size showed poorly sorted immature grains with a dominance of silt particles (85 percent), followed by sand (8.5 percent) and clay (6.5 percent). The SS estimates revealed a total suspended sediment yield of 1285 tons km sup(-2) yr sup(-1) and physical erosion rate of 0.47 mm yr sup(-1). Considering the socio-economic importance of the Himalayan region, the present study will help to evaluate the water and sediment budget of the Chandra River, Western Himalaya and to establish their relationship to the meteorological conditions in the basin.