%0 Journal Article %T Integrating GIUH and Verified Variable-Parameter SCS-CN models for Estimation of daily Runoff of Watershed (Case Study: Kashkan Watershed, Lorestan Province) %J Iranian Journal of Soil and Water Research %I University of Tehran %Z 2008-479X %A Hosseini, Seiyed Mossa %A Yamani, Mojtaba %A Jaffar-Beiglou, Mansour %A Geravand, Fatemeh %D 2019 %\ 01/21/2019 %V 49 %N 6 %P 1377-1393 %! Integrating GIUH and Verified Variable-Parameter SCS-CN models for Estimation of daily Runoff of Watershed (Case Study: Kashkan Watershed, Lorestan Province) %K : Kashkan Watershed %K Rainfall-Runoff Modeling %K Morphometric Characteristics %K GIUH Theory %K SCS-CN Model %R 10.22059/ijswr.2018.244525.667777 %X Recently, the Geomorphologic Instantaneous Unit Hydrograph (GIUH) model has been widely employed for estimation of watershed response to rainfall. This model is based on the convolution integral of the effective rainfall by the ordinates of IUH product. In this study, the effective rainfall has been estimated using morphometric characteristics of Kashkan watershed, simulation of daily rainfall-runoff by GIUH model and four modified Soil Conservation Service-Curve Number (SCS-CN) models. The effect of temporal variations of and initial abstraction ratio () have been also investigated as a function of rainfall depth (P) in the SCS-CN models. The results of the proposed integrated models (GIUH and the modified SCS-CN models) were investigated using the percentages of errors correspond to; peak flow estimation (%), arrival time to the peak flow () and the runoff volume (%) for three periods of drought, normal, and wet for the fixed- and varied-parameter conditions. The results showed that the variations of CN and λ parameters proportion to the rainfall depth in SCS-CN model are more effective than the fixed-parametes of the SCS-CN model,  . Additionally, the odified forms of SCS-CN models are more efficient that original form (i.e. keeping constant of  equal to 0.2). The results of this study indicates the necessity of employing the modified forms of SCS-CN model and considering the temporal variations of CN and λ parameters for calculation of effective rainfall as an input parameter of rainfall-runoff models, especially in watersheds undergoing human impacts. %U https://ijswr.ut.ac.ir/article_69706_6f0afe1b9de86be0b3a5333f0aaad141.pdf