Study On The Reponses Of Flood Characteristics To Land Subsidence Of Detention Basin

China is one of the countries prone to serious natural disasters, as is located inAsian monsoon region, its rainfall is very unevenly distributed in space and time,there will be very high possibility of the flood with high peak and large volume. Inorder to withstand a larger flood and ensure the safety of the key cities and regions,we can take the measure that open up the specified area (i.e., rivers, lakes at al.) asdetention basin to diverte flood. Detention basin, which is an important part of ourcountry’s flood control system, can ensure the flood control security of the key citiesand reduce flood disaster effectively. Detention basin has fertile land which rarely putinto use. In recent years, with the increasing of population and the development ofeconomic rapidly, the overdraft of groundwater leads to rapid decline of groundwatertable, which consequently triggered and aggravated serious land subsidence. Groundsubsidence decreases the flood control standard of levees or dykes and flooddischarge capacity of the river courses dramatically, resulting in increasing the risk offlooding.Hence it is very necessary to research the impact of land subsidence factors on the flood characteristics in the detention basin.This paper analysis the use of the existing hydrologic and topographic data,using a case study from Jiakouwa flood storage and detention area, establishes themathematical model for flood routing infection with using MIKE21FM model, andsimulates flood routing process of100year flood in Daqing River. The model webuild take fully account of the influence of ground subsidence. The research resultscan provide it basis for decision-making and scientific guidance, which flood controloperation in Daqing River and flood control and disaster in Huangzhuangwa detentionareas. In this paper, the main contributions are as follows:(1) Based on the existing ground elevation data of Jiakouwa, we analysisrespectively ground settlement and its spatial distribution characteristics from1977to2002,2002to2010, draw Water-storage capacity curve and Water-area curve, andanalysis the influence of surface subsidence on storage capacity and the submergedarea.(2) Set up2-D hydrodynamic model of Jiakouwa flood storage and detentionarea, and validate the model by using the flood characteristics index of water andsubmerged area. The model and parameters of the screen is rational because theresults of simulation are identical to the data of tests. (3) Simulate the100year flood under the condition of road block water andnon-road block water by using the ground elevation grid model in years1977,2002and2010in Daqing River. By comparing with the water level, water depth andsubmerged area that the model calculated, influence of land subsidence on floodcharacteristics is analyzed.