Proportion of the Actual Evapotranspiration, Infiltration, Surface and Subsurface Flow Parameters from Entry Annual Rainfall in the Khuzestan Province

To optimal and sustainable management of water resources in watershed scale, estimation of water balance and important to know of the different parameters of the water balance is inevitable. Goal of this study, is estimating the volume of actual evapotranspiration, infiltration, surface and subsurface flow based on hydrologic balance in Marghab and Abgelal watersheds. Hydrological balance in the hydrological stations these watersheds was calculated using the Salas approach. Results indicated that in Abgelal watershed, from 597 mm average of rainfall, about 438 mm is evaporated and about 95 mm as runoff out of the watershed. Thus, 64 mm of the total rainfall infiltrated. In the Marghab watershed, maximum of rainfall as runoff out of the watershed, so from amount of annually rainfall that is equal with 641 mm, amount of 192 mm as evapotranspiration and amount of 72 mm as infiltration and 377 mm as runoff out of the watershed. Model evaluation for the two stations was conducted using the error parameters such as Nash – Sutcliffe Error (NSE), Root-Mean-Square Error (RMSE) and Mean Absolute Error (MAE), results indicate that performance of model is better in Marghab station than Baghmalek station.