Research On Water Resources Evolution And Engineering Model Of Waterlogging Control In Northern Anhui Plain

The plain of Northern Anhui lies in the north of Huaihe river,and is located in the climatic transition zone of the north and south of China.For a long time,due to the natural factors such as climate and geographical environment and the comprehensive influence of human activities,the waterlogging and drought disasters in northern Anhui plain are frequent,and the space-time distribution is complex,especially the waterlogging disaster,which is wide,large and heavy,has not been effectively contained.It has become one of the major threats to agricultural production.The project is based on the need for regional waterlogging disaster management,according to the idea of "data collection analysis-evolution law recognition-drainage index determination-engineering mode construction".Based on the collected long series observation data,the temporal and spatial evolution of water resources and waterlogging disasters in northern Anhui plain are identified.With the establishment of farmland drainage index,combined with the hydrological effect of waterlogging in Wudaogou hydrology and water resources experimental station and the hydrologic theory,the layout and key parameters of the regional waterlogging engineering are put forward.The main research results include:(1)analysis of evolution law of regional water resources and waterlogging disasters.The average annual precipitation in northern Anhui plain decreased by 6.72 mm in 1956~1979,increased by 6.57 mm in 1980~2009 and decreased by 14.88 mm in 2010~2014;the runoff showed an obvious decreasing trend before 1980 s,and a slight decrease in 80 s,a slight decrease in 90 s,and a significant increase after 21 th century;the abundant periods of shallow groundwater are 15,the average recovery period is 2.7 years,while the dry periods are 13,the average recovery period is 3.2 years.The average shallow groundwater depth is 2.48 m,the shallower depth is 0.95 m and the deepest depth is 5.72m;the disaster area and disaster rate of the regional flood disaster are all decreasing,but the change is not significant,and the tendency rate is-7.97 ten thousand ha/10 a,-11.90 ten thousand ha /10 a,-0.35%/10 a and-1.59%/10 a,respectively(2)proposing of the engineering mode and key parameters of farmland drainage system.The northern part of the northern Anhui plain is arranged according to the "Three-One ditches" form.The distance between the big ditch is 2.0~3.0km,the depth is 3.0~4.0m;the distance of the middle ditch is 800~1000m,the depth is 2.0~2.5m;the distance of the small ditch is 150~250m,the depth is 1.0~1.5m;The middle and southern areas are arranged according to the "Three-Two ditches" form.The distance between the big ditch is 1.5~2.5km,the depth is 3.5~5.0m;the distance of the middle ditch is 600~800m,the depth is 2.5~3.0m;the distance of the small ditch is 150~250m,the depth is 1.0~1.5m.According to this layout,the control area of the big ditch,the middle ditch and small ditch are 15000~18000mu,1500~3000mu and 150~200 mu,respectively.The research results have important practical significance for solving regional waterlogging disasters and promoting regional agricultural production.