An Investigation on Spatial Variability of Runoff and Soil Loss in Summer Rangeland

Study of spatial variability of runoff and soil loss and the understading of their distribution is vital for strategic planing in water and soil conservation. In this study spatial variability of runoff and soil loss were investigated in summer rangeland of Nesho in the Mazandaran province. For To do this، 110 runoff and sediment yield samples were collected by a systematic sampling strategy on a regular grid with a dimension of 30×30 m using simulated rainfall with a 2 mm/min intensity and 11-minute duration on 0. 09 m2 plots. All the samples were transported to the laboratory، and their characteristics including sediment yield and concentration were analyzed. After data normalization، classical statistical analysis was used to describe runoff and soil loss properties. Geo-statistical analysis was also applied to illustrate the spatial correlation of runoff and soil loss so that their spatial distribution was finally mapped using the kriging technique. The highest and lowest coefficient of variation was related to sediment yield and time to runoff generation with 93. 75 and 28. 43 percent، respectively. Fitted models for runoff and sediment characteristics were spherical and exponential models، respectively. Based on the results of variography، runoff volume and sediment concentration with 1010. 90 and 831 meters showed to respectively have the highest and lowest impacts on runoff and sediment characteristics. Given the strong spatial dependancy of these variables، it can be stated that kriging method has high cabability in estimating these variables at unsampled points as well as their zoning.