Comparison of Runoff Generation and Sediment Yield in Two Land Usesof Range and Dry Farming

Land use utilization based on its capability and susceptibility is necessary for proper management of different regions. In this regard, the conversion of rangeland areas to dry farming and its consequent effects on soil erosion is a crucial problem that has to be carefully investigated. The present study therefore attempted to study the runoff and sediment rates in experimental plots located in two land uses of rangeland and dry farming lands with a slope of 5 percent by using rainfall simulator. The research was conducted during summer 2009 in Tiregan watershed located in Daregaz Township, Khorasan Razavi Province. The experiments were taken place through simulation of rainfall with intensity of 1.7 mm min-1 in two upper and lower positions, in eastern and western aspects of the slope in both the land uses. Afterwards, the runoff threshold was determined and the runoff samples were collected in small containers. The results of the study showed that the average runoff threshold in rangeland was 3.36 minutes earlier than that occurred in dry farming land. The runoff volume in rangeland plots was also 2.3 times more than dry farming land did. The sediment yield in the upper position in eastern aspect of rangeland treatment was lesser than dry farming treatment did. The difference was not significant in other treatments. The turbidity rates were also significantly more in dry farming lands compare to what recorded for rangeland areas.