Discharge recession from runoff plots in representative mountain area in North China

Rainfall simulation on representative plots(5 m wide and 10 m long) in a mountainous area of North China was carried out to compare water discharge and recession characteristics by surface runoff,soil-layer flow and mantle rock flow.Results show that soil-layer flow recesses first with the longest duration and lowest discharge,surface runoff recession which is affected by rainfall and topography ceases with rainfall stop,and mantle rock flow recesses generally ensuing surface runoff recession.Duration and intensity of rainfall are dominant factors affecting discharge recession.The amount of surface runoff recession has a power trend to the increase of rainfall duration.Rainfall intensity and surface runoff recession present a logarithmic regression and rainfall intensity and summation of discharge recession from soil-layer and mantle rock show a linear relationship.Rainfall intensity also affects the proportion of recession discharge by surface runoff,soil-layer flow,and mantle rock flow to total discharge,which are 7.8%,1.7% and 5.9%.With the increase of rainfall intensity,the proportion of recession by surface runoff increases linearly when the intensity is lower than 1.5 mm/min.However,the proportion of surface runoff recession to total discharge decreases to very low if the intensity is above 2 mm/min.The proportion of mantel rock recession has a power trend to decrease with the increase of intensity, and that of soil-layer recession is generally low.The result shows that the recession constant in this area should be divided into surface recession(0.75) and soil-layer and mantle rock recession(0.94).These primary results will present parameters for the further research of recession on hydrological processes on slopes and catchment.