Effects of different rainfall intensities and slope gradients on runoff and phosphorus losses on sloping lands in Miyun Reservoir Area
[Objective]Phosphorus is the main factor causing eutrophication in Miyun Reservoir Area.The aims of this study are to explore the characteristics of runoff and phosphorus losses in sloping lands in Miyun Reservoir Area,and to provide data support and theoretical basis for the prevention and control of water eutrophication pollution in Miyun Reservoir Area.[Methods]Indoor artificial rainfall experiments were used to study the characteristics of surface runoff and subsurface runoff and the pattern of phosphorus loss with runoff under different rainfall intensities(40 mm/h,60 mm/h and 80 mm/h),slope gradients(5°,10° and 15°)and different cover conditions(bare land and alfalfa).[Results]The initial runoff generation time of surface runoff and subsurface runoff under different cover conditions advanced with the increase of rainfall intensity and slope gradient.The surface runoff and subsurface runoff rates under different cover conditions increased with the increase of rainfall intensity.Under the same rainfall intensity,the runoff rate of bare land and alfalfa surface runoff decreased in the order:5°＞15°＞10° slope gradient.The total phosphorus(TP)loss concentration of surface runoff and subsurface runoff increased with the increase of rainfall intensity under different cover conditions,and the TP loss concentration of surface runoff under the same rainfall intensity reached the maximum at 10° under the same cover condition,while the TP loss concentration of subsurface runoff increased with the increase of slope gradient.The loss of TP in surface runoff under different cover conditions increased with the increase of rain intensity.Under the same rainfall intensity,the TP loss of surface runoff increased with the increase of slope gradient,and the TP loss of surface runoff under the condition of alfalfa decreased in the order:10°＞15°＞5°slope gradient.Alfalfa had a good inhibitory effect on TP loss in runoff,and the control efficiency could reach to 61.17％.Surface TP loss with surface runoff accounted for more than 53.76％of the total loss under different cover conditions.Correlation analysis showed that rainfall intensity was the main influencing factor on runoff and phosphorus loss on sloping land in Miyun Reservoir Area.[Conclusion]Sloping land runoff and phosphorus loss in Miyun Reservoir Area are affected by rainfall intensity,slope gradient and vegetation cover,and rainfall intensity is the main influencing factor,surface runoff is the main way of phosphorus loss.
万方数据
维普
