Discharge and sediment loads of two streams in the mid-hills of central Nepal

Abstract

Stream flow, nutrient loading, and sediment yield closely reflect land use and management practices in relation to growing seasons in mid-hill watersheds of the central Himalaya. A preliminary study was conducted to determine approximate total water discharge and sediment yields from the Galaundi and Pokhare catchments. Mean discharge and sediment loads during the 2002 rainy season were 2.1 m3?s-1 and 0.9 kg?s-1 for Galaundi Khola and 0.45 m3 s-1 and 0.28 kg?s-1 for Pokhare Khola. Estimates of total annual discharge of water and sediment were, respectively, 27.8 million m3 and 11,400 t (Galaundi) and 6.4 million m3 and 3,500 t (Pokhare). These corresponded to about 71.6% and 60.4% of total rain volumes and soil loss rates of 5.18 t?ha-1 and 5.83 t?ha-1 for Galaundi and Pokhare sub-watersheds, respectively. Good correlations were observed for stream discharge vs. sediment concentration (R2 = 0.83 and 0.94 respectively) and rainfall amount vs. discharge (R2 = 0.94 and 0.96 respectively) for both streams. Key words: stream flow, sediment concentration, land use, pre-monsoon, sub-watershed Himalayan Journal of Sciences 2(3): 51-54, 2004