Evaluation of Several Empirical Models in Estimating Annual Runoff (Case Study: Hesarak Catchment in Northwest of Tehran)

The use of geographic information systems (GIS) and remote sensing is common to facilitate the estimation of catchment's runoff in the last century. This action is performed by using the rainfall-runoff model, which includes climate and geomorphological changes. One way to estimate the runoff height is the Curve Number (CN) method that shows the hydrological behavior of catchment. In this research, the Arc-GIS software was used for mapping curve number by integrating vegetation maps, land use and soil hydrological group, and then the annual runoff height map of Hesarak catchment was prepared. In addition, by using empirical methods, annual runoff of the study area was compared with I.C.A.R, Justin, Angeli di Sousa, and SCS-CN methods. The comparison of estimated runoff values in different methods with observations of runoff showed that the result of SCS-CN method has more adaptation to the observed runoff and discharge. The advantage of this model is the use of different parameters such as annual precipitation, soil holding, and permeability of the curve number of the basin, which causes the measured runoff to be closer to the observed value.