Measurement and distribution of rainfall, runoff and soil losses from the selected watersheds in the Hindu-Kush Himalayan region

Population pressure and climate change effect water and erosion related issues of the Hindu Kush-Himalayan region. Presently problems in terms of water are mainly concerned with quantity. "Too much " during rainy season and "Too little " during the dry period of the year are the basic problems. With increasing population and intensifying agriculture there is no relief on the water resources in sight. In many places of the region depletion of ground water and drying up of springs is taking place. During monsoon however vast amounts of water are leaving the upland watersheds as surface runoff, causing erosion on the slopes, sedimentation and flood problems further downstream. For this purpose runoff and sediment losses were monitored on erosion plots on different land uses i.e. degraded, pasture, forest and agriculture land. Total annual rainfall in the region ranges between 972 mm to 2400 mm. On the basis of quarterly distribution of rainfall, about 44 to 66% rainfall occurs in quarter 3, which prolongs from June to August, which is mostly monsoon season in the region. In general about 60 % of the annual rainfall occurs in the monsoon season. Results show that runoff and soil losses were higher in the months of May to September, when rainfall duration and intensity were higher in all the watersheds. There were some big events which contribute most of annual runoff and soil loss in the area. Highest runoff was recorded from degraded land uses. Most of the runoff in all watersheds occurred in 2nd and 3rd quarter. In JK (92 to 96%), in HK (75 to 90 %), in BG (83 to 94%) and in XI (87 to 90 %) runoff was recorded in 2nd and 3rd quarter. Soil loss from JK was recorded highest in most of the land uses while it was very low in HK and BG watersheds. Soil loss in April to September was higher in almost all watersheds