University of Tehran Press Iranian Journal of Soil and Water Research 2008-479X 48 5 2018 01 21 WEPP model efficiency in estimation of runoff and soil loss in stony rangelands of Khamesan watershed, Kurdistan WEPP model efficiency in estimation of runoff and soil loss in stony rangelands of Khamesan watershed, Kurdistan 1031 1042 64760 10.22059/ijswr.2017.212045.667504 FA Naser Khaleghpanah University of Tehran Hossein Asadi University of Tehran Mahdi Shorafa University of Tehran Manoochehr Gorji University of Tehran Masood Davari University of Kordestan Journal Article 2016 08 02 The aim of this study is to evaluate the efficiency of WEPP model to estimate the runoff and soil erosion under natural events at plot scale in rangelands of Khamesan watershed, Kurdistan. The runoff and sediment induced by events leading to runoff were measured over a three year period (2011 - 2013) in eighteen plots of 24 m long and 1.8 m wide (6 hillslopes with three plots in each). Concurrently, the input data including soil characteristics, vegetation and ground cover were evaluated and recorded during the period.An overall of 24 events were investigated. After calibrating the model  using the eight events’ data based on the single event section of the model, the validation of WEPP model was carried out using the 16 remaining events. The model estimated the runoff and soil erosion with an acceptable accuracy under natural events in rangeland hillslopes containing significant amounts of rock fragments. The soil erosion estimations were somewhat better than the total runoff. In general, the model efficiency was lower in the hillslopes with higher rock fragments (especially rock cover) and higher percentage of lime compared with the other hillslopes. It seems that rainfall intensity pattern during each event also had a significant effect on the model estimations. In WEPP model for single event estimations, only a number of storm characteristics are used as input data, and intra-storm variations are not considered which may have a significant impact on the amounts of runoff and sediment. <strong> </strong> The aim of this study is to evaluate the efficiency of WEPP model to estimate the runoff and soil erosion under natural events at plot scale in rangelands of Khamesan watershed, Kurdistan. The runoff and sediment induced by events leading to runoff were measured over a three year period (2011 - 2013) in eighteen plots of 24 m long and 1.8 m wide (6 hillslopes with three plots in each). Concurrently, the input data including soil characteristics, vegetation and ground cover were evaluated and recorded during the period.An overall of 24 events were investigated. After calibrating the model  using the eight events’ data based on the single event section of the model, the validation of WEPP model was carried out using the 16 remaining events. The model estimated the runoff and soil erosion with an acceptable accuracy under natural events in rangeland hillslopes containing significant amounts of rock fragments. The soil erosion estimations were somewhat better than the total runoff. In general, the model efficiency was lower in the hillslopes with higher rock fragments (especially rock cover) and higher percentage of lime compared with the other hillslopes. It seems that rainfall intensity pattern during each event also had a significant effect on the model estimations. In WEPP model for single event estimations, only a number of storm characteristics are used as input data, and intra-storm variations are not considered which may have a significant impact on the amounts of runoff and sediment. <strong> </strong> https://ijswr.ut.ac.ir/article_64760_24e071547f4e77e6355e4a572578693f.pdf