Factors Influencing the Runoff Generation Threshold in Small Basins

Runoff generation threshold dependent on the different parameters such as rainfall features, geometric characteristics of the basin, soil characteristic basin, vegetation and primary humidity. Runoff outbreak in big basins is determined by using the rainfall data and the recorded data by hydrometric stations. In small basins, estimating the runoff outbreak is challenging due to the lack of hydrometric station. In this research, the rainfall events and runoff were measured in Sanganeh Kalat watershed (the studied sub basins are small and their area is about 1 ha and the whole area is about 7 ha). The rainfall was recorded by a rain gauge system and runoff were recorded by five lymonograph systems which four of them were installed in the output of sub basins and the remaining one was installed in the main output basin to record data for two years. Different effective factors in runoff outbreak were studied including rainfall intensity, basin area, channel slope and basin slope, channel density and rainfall in some days ago. Results show that the rainfall intensity and basin area play the most in runoff outbreak. There is a relationship between runoff outbreak and these two factors which have high precision.