Study On Flood Risk Assessment And Risk Removal Method Of Check Dam In Wangmaogou Watershed

The Loess Plateau is the most serious area of soil and water loss in China,a special natural geological environment in China,and the most serious area of soil and water loss in the world.In the long-term production practice,the local people have found that building check dams in ditches is an effective measure to prevent and control soil and water loss,and check dams play an irreplaceable role in controlling soil and water loss on the Loess Plateau.However,with the increase of hceck dam running time,the safety problems of check dams become more and more prominent,and the disasters caused by check dams become more and more serious.Based on the analysis and calculation of the secondary precipitation data of Wangmaogou watershed,combined with DB-IWHR model and Analytic hierarchy process(AHP),this paper studies the flood control risk and risk elimination methods of check dams in Wangmaogou watershed,and draws the following main conclusions:(1)Using hydrological manual and DB-IWHR model,the number and flood characteristics of check dam break in Wangmaogou watershed under different recurrence periods are analyzed.When the flood occurs in 10?20?30?50?100 and 200 years,there are 2?3?3?3?4 and 5 check dams in Wangmaogou watershed will be a dam break;When the flood occurs in 10?20?30?50 and 100 years,the flow of dam break in Huangbaigou no.2 dam is the largest,and the flow of dam break in Huangbaigou no.1 dam is the largest in the case of flood in 200 years;The dam-break flood process shows a trend of steep increase at first and then slow decline,and the peak time decreases with the increase of return period.(2)Taking the product of flood inundation loss and flood occurrence probability as the flood control risk value,the flood control risks of different check dams in Wangmaogou watershed are calculated,and the changing trend and key flood control objects of check dams in Wangmaogou watershed under different recurrence periods are made clear.The flood control risk values of different check dams and Wangmaogou dam system in Wangmaogou watershed basically decrease with the increase of flood return period,but individual check dams show different trends due to dam break in different return periods.In the event of 10?20?30?50?100?and 200year flood,there are 2?3?3?3?4 and 5 key flood control objects in the basin respectively,and there is one secondary key flood control object in the event of 20-year flood(3)In this paper,the danger situation of different check dams in Wangmaogou watershed is evaluated,and the risk elimination methods of different check dams are determined according to the treatment measures of different diseases and dangers.Huangbaigou no.2 dam and Nianyangou no.3 dam need to be backfilled and compacted.Huangbaigou no.2 dam needs to build spillway,Nianyangou no.3 dam ditch dam needs to build shaft or horizontal pipe;The Beitagou dam needs to backfill and tamp the gully,pour the horizontal pipe as a whole and add flood discharge facilities;Hejiamao dam needs manual excavation and backfilling of cracks,backfilling and tamping of gullies,and construction of shafts or horizontal pipes;Guandigou no.1 dam needs to add a filter layer at the landslide,use microporous bellows to discharge water,backfill and tamp the gully,and cut the slope and excavate the shaft;Huangbaigou no.1 dam needs to fill and tamp the gully,add a filter layer at the landslide,use microporous bellows to discharge water,manually excavate and backfill the cracks,irrigate the shaft as a whole and set up flood discharge facilities;Nianyangou no.1 dam needs to cut the slope and dig the shaft;the Wangmaogou no.2 dam,Nianyangou no.2 dam and the Sidizui dam need to cut and excavate the horizontal pipe or shaft,and the Guandigou no.3 dam needs to build a shaft or horizontal pipe.