Design storm studies over the Bhagirathi and the Dhauliganga river catchments in Uttranchal State

摘要

For all round developments of any region, knowledge of precipitation climatology is most essential. Large number of rainfall studies are available for plain area river basins. It is now essential to carry out such studies in the mountainous regions like the Garhwal Himalayan region where orography plays important role in rainfall distribution. These studies can be useful for planning and design of barrages to generate hydropower by storing surface runoff. The knowledge about space time distribution of precipitation is also useful for agricultural operations over hilly terrain where irrigation through a network of canals is not feasible as in plains. Moreover, knowledge of maximum precipitation is also required for the design of dams and drinking water tanks for villages in the interior of hilly terrain. In this paper, design storm studies have been carried out over the two catchments in Garhwal Himalayan region, viz. (a) the Bhagirathi up to Loharinag Pala (area 3316 km~2) and (b) the Dhauliganga up to Tapovan Vishnugad (area 3100 km~2) using rainfall data of about 73 stations around the study region for their available period from 1901. Standard projects storms (SPS) and probable maximum precipitation (PMP) rain depths were estimated by physical and statistical methods. Using SRRG data from nearby stations, lime distribution analysis has been carried out. The time distribution can be used to estimate design rain depths of shorter intervals