Experimental Study On The Rainstorm And Mountain Flood Disaster Mechanism Under The Action Of Silt Dam

As one of the important soil and water conservation engineering measures for preventing and controlling soil erosion in the Loess Plateau,silt dams play a crucial role in water storage,soil conservation,flood control and disaster reduction.This study conducted an indoor simulated rainfall experiment in a small watershed,using the Qiaogou small watershed model in Suide County,Shaanxi Province as the research object.It systematically analyzed the runoff and sediment production process,water and sediment variation characteristics,hydrodynamic parameter variation characteristics,erosion dynamic parameter variation characteristics,and the response relationship between dynamic parameters and runoff and sediment production in a small watershed in Huangqiu District under different rainfall intensities and the coupling of different silt dam measures,This paper expounds the regulating effect of rainfall intensity and silt dam coupling on runoff and sediment,which provides a theoretical basis for revealing the rainstorm runoff process and disaster mechanism in the basin,and scientifically evaluating the effect of water and soil conservation measures on water and sediment regulation.The main conclusions drawn in this article are as follows:(1)This study elucidates the characteristics of runoff and sediment production in small watersheds under different configuration scenarios of silt dams.Under the effect of rainstorm,the runoff and sediment concentration of small watershed in Huangqiu District increase with the rainfall duration,and the layout of silt dams has a significant effect on reducing the increase rate of runoff and sediment concentration.When the rainfall intensity is 60 mm/h,the average sediment transport rate,fluctuation amplitude of sediment transport rate,and peak sediment yield under the double dam arrangement method are all smaller than those under the single dam arrangement method,which have decreased by 53.08%,66.57%,and 65.51%respectively,indicating that the double dam arrangement has a certain synergistic effect on intercepting runoff and reducing peak flow.Under the same configuration of silt dams and different rainfall intensity scenarios,the increase in runoff with a rainfall intensity of120mm/h is 2.94 times that of 60mm/h,and the increase in sediment concentration is 13.87 times that of 60mm/h.Both rainfall intensity and the layout of silt dams can have a significant impact on the runoff and sediment production in the channel.(2)This study analyzed the changes in dynamic parameters of mountain floods under different configuration scenarios of silt dams.The increase in rainfall intensity can increase the flow velocity of runoff by increasing the runoff flow in the channel.The placement of silt dams can reduce the downstream flow velocity of silt dams by hindering runoff discharge.At the same time,the flow velocity is affected by the location of silt dams,and the dam control area is large,which has a greater impact on reducing the flow velocity and delaying runoff erosion.When the rainfall intensity is 60 mm/h,with the arrangement of silt dams,the flow pattern of runoff evolves from laminar to turbulent flow with the increase of rainfall duration.Under any arrangement of silt dams,the flow pattern of runoff exhibits a slow flow pattern;When the rainfall intensity increases to 120 mm/h,the runoff shows a turbulent flow pattern,and the process of runoff flow pattern changes from a slow flow pattern to a rapid flow pattern;There is a significant negative correlation between the resistance coefficient,Manning’s roughness coefficient,and runoff sediment concentration.The smaller the resistance coefficient,the weaker the obstruction effect on runoff sediment.(3)This study clarified the dynamic characteristics of mountain flood erosion under different configuration scenarios of silt dams.Under different rainfall intensities and different configuration scenarios of silt dams,the runoff shear force,runoff power,and runoff erosion power all increase with the increase of rainfall duration.The erosion ability of soil caused by mountain flood runoff gradually increases over time,and an increase in rainfall intensity will cause more severe fluctuations in runoff shear force.The layout of silt dams can retain runoff,It can effectively reduce the runoff shear force,runoff power and runoff erosion power,reduce the erosion of gully soil during runoff movement,reduce the erosion of soil in the downstream gully,and regulate the runoff and sediment process,and the erosion of runoff on the gully is most obvious under the layout of double dams.(4)This study revealed the response relationship between mountain flood dynamic parameters and runoff and sediment yield under different configuration scenarios of silt dams.According to the correlation analysis,the Reynolds number has a high correlation with the runoff sediment concentration,and the runoff power has a high correlation with the runoff sediment concentration.The Reynolds number and runoff power among the various dynamic parameters of channel runoff can be considered as the dynamic factors that can better describe the erosion and sediment yield under different rainfall intensities and the layout of silt dams.