عنوان مقاله [English]
At present due to lack of proper utilization and management in non-renewable natural resources, most of the watersheds are in critical conditions. Since about 80 percent of Iran watersheds located in arid and semi-arid climatic conditions, thus addressing the issue of optimal utilization of rainfall is most important. In this research, the surface of micro catchment was isolated by plastic to increase runoff coefficient. Six treatments and three replications were considered in down part of the micro catchment. The surfaceswere prepared by available materials such as greenhouse plastic, gravel, fine and coarse sand, and for infiltration, a filter with 50 cm depth and 15 cm diameter was used. Soil moisture in 30 and 50 cm depths, was monitored by Time Domain Reflectometry (TDR). The first step eas started by cleaning grasses and compacting soil surface and monitoring 18 rainfall events. In the next step, soil surface was covered by plastic and 21 rainfall events were monitored. Results showed that the runoff coefficient increases by six to 47 percent or 7.8 times more than natural condition. The statistical analysis by T-test showed that all treatments and depths of isolated and natural conditions have significantly different results in 90 percent level of confidence. Finally, the average soil moisture content for isolated condition in comparison of natural condition is 6.4 and 9.4 percent in 50 and 30 cm of soil depth, respectively. In other hand, isolated surface increased soil moisture 3.8 and 2.8 times compared to treatments in 50 and 30 cm of soil depth, respectively.