Author : Ghazala Tabesh and V.G. Bhave

Proper estimation of runoff is required for planning, efficient design and management of stream basin projects that deal with utilization and preservation of water for various purposes. The transformation of rainfall into runoff over a catchment is a complex hydrologic phenomenon and includes processes of infiltration, depression storage, interception, percolation and evaporation. Present study aims at estimating yield at Pashadan dam site across Karokh River in Afghanistan. The catchment area at dam site is about 1851 sq km. The available rainfall and runoff data in study area was collected. These data were analyzed for checking homogeneity. It was seen that runoff data is available for short time and rainfall data are available for relatively long period. In order to estimate the yield at dam site different methods are selected from those reported in literature. Comparison of results is made using criteria like closeness of observed data, matching of trend, ease of computations, comparison of deviation etc. Study is conducted to review the methods and select the one(s), which are applicable for present scenario. Results obtained were analyzed using above criteria. Soil conservation services curve number method with annual step is noticed to be most suitable for Pashadan site.

Keywords: Water Yield Estimation, Rainfall Runoff Conversion, Inadequate data, Thomas Fiering model, SCS-CN Method, Correlation, Empirical Method

Article published in International Journal of Current Engineering and Technology, Vol.5, No.4 (Aug-2015)