Evaluation of sediment yield under open grazing and exclosure micro-watersheds, case study: Sangnaeh area of Kalat

Rangeland exclusion is one of the watershed management methods that is applied for range rehabilitation. However, most rangeland hydrology studies have been focused on exclusion effects on soil loss at plot scale, whereas their effects on sediment yield at micro-watershed in seasonal and annual scales have rarely been considered. The present study was conducted in two sub-watersheds under exclosure and open grazing treatments, with area of 1.0 and 1.1 ha, respectively, in Sanganeh Watershed, Khorasan Razavi Province, Iran. Runoff and sediment associated with 56 storm events occurred during 2006 to 2016 were estimated at the main outlet of the watershed. The results showed the significant decreasing effect of exclosure treatment on sediment yield at micro-watershed scale (p≤0.05). So that, 582% decrease in sediment yield was obtained in exclosure treatment compared to open grazing. Results also showed seasonal and annual variations of exclosure on hydrological processes so that, maximum and minimum differences in sediment yield among study treatments were founded. The results of this study suggest that livestock grazing management during sensitive seasons as well as rangeland exclosure, if its social problems are resolved, is a practical solution to reduce watershed sedimentation.