Estimation of Surface Runoff in an Ungauged Basin Using SCS-CN Method, A Case Study of Manair River Basin in Telangana, India

Abstract

The present research work was carried out for estimation of surface runoff in an ungauged basin by SCS-CN curve method. Satellite Images, digital elevation model data, hydrological Soil Data and precipitation data combined with Geo spatial technologies was used for land use/land cover classification, drainage extraction, basin delineation and for the surface runoff estimation of the study area. The study area Manair basin is located under 4 districts Karimnagar, Kamareddy, Medak and Rajanna-Siricilla districts of Telangana State, Southern India. Maniar River is one of the major tributary to the Godavari River. The Manair Basin is further divided into three sub basins in which three dams named Upper Maniar dam, Mid Manair dam and Lower Manair dam are there across the Manair river basin. In the present study the surface runoff estimation is computed for the entire Manair basin. The total drainage area of basin is 6668.212 sq. km and morphometric analysis shows sub-dendritric and dendritic pattern. The Maniar basin is in Elongated shape which indicates heavier flow for the long duration. The runoff estimation by SCS-CN curve method is determined by integrating land Use/land cover classification with antecedent moisture condition and hydrological soil groups. The study area receives the good rainfall but most of it is lost by surface runoff due to overland flow and Clay soil texture present in the study area. It was perceived from the results that overall increase in runoff is directly proportional to precipitation in the study area. The daily precipitation data from 11 weather stations which are present in the study area have been collected during the years 2010 - 2018 and were used to estimate the daily runoff from the basin. Daily and annual runoff has been calculated from the monthly rainfall data for the years of 2010 to 2018 in the basin.