Study On Vulnerability Of Flood Disaster In Chaohu Basin Based On Land Use

Under the background of global climate change,with the increase of the intensity of human activities,the mode of land use has changed significantly.The range of flood disaster has been continuously expanded,and the losses of disaster are increasing.The vulnerability of the hazard-affected body affects the degree of casualty loss,so it has become a research hotspot currently.The study of disaster vulnerability can effectively improve the responsiveness of the natural social system and maintain the orderly development of the system.Firstly,based on the object-oriented decision tree algorithm,the remote sensing images were interpreted,and the distribution of land use in the Chaohu Basin were analyzed.Secondly,to simulate the distribution of submergence range and submerged depth in Chaohu basin,the MIKE FLOOD model was used to couple MIKE 11 HD(one dimensional hydrodynamic model)with MIKE 21 FM(two dimensional flood model).Thirdly,based on the results of questionnaires and disaster data from the counties'civil service,the loss of different land use under different submerged depths and the total value of property were counted.The disaster loss rate of different land use were calculated,and the vulnerability curve were constructed.Then,the vulnerability of flood disaster in Chaohu basin was evaluated based on grid scale and administrative unit.Lastly,the distribution of flood occurrence time,submerged area,submerged depth and flood vulnerability under different rainfall intensity were simulated in Chaohu basin.The main conclusions were as follows.(1)The land use pattern of Chaohu basin is classified by the object-oriented decision tree algorithm in 2015.Among all the classifications,the area of forest is the largest(2,642.88 km~2),the area of cultivated land(2,432.07 km~2)and construction land are larger(2,424.24 km~2),the area of water area and grassland is smaller,and the area of unused land is the smallest(7.83 km~2).Compared with the land use of Chaohu basin in 2005,the area of cultivated land decreased significantly,which is reduced by about 3,022.84 km~2.The area of forestland and construction land increase by 983.66 km~2 and 1562.81 km~2 respectively,and the changes of others are small.(2)The vulnerability curve of different land use in Chaohu basin are constructed,including paddy field,dry land,woodland,shrub forest,rural settlements,urban land,industrial land,traffic land,high coverage grassland,lakes,rivers,ponds,bare land.Among them,paddy fields and drylands are the most severely affected by floods.Urban land,industrial land and rural residential areas are seriously affected.Shrubbery,high coverage of grassland,and woodland are relatively low.Reservoirs,ponds,traffic land,river channels,lakes and bare land are least damaged.(3)The submergence range and submerged depth of Chaohu basin are simulated under the condition of heavy rainfall in 2016.The inundated area of Chaohu basin is mainly located around Chaohu Lake.The eastern part of Chaohu city,the southeast of Baohe district,the west of Feixi county,the east of Shucheng county and the northwest of Lujiang county have a large submerged area,and the submerged depth are deeper than other areas.The vulnerability of Chaohu city,Feidong county,Baohe district and Yaohai district,Lujiang county,Shucheng county are relatively high,while the vulnerability of Changfeng county,Jin'an district and Luyang district are low.(4)The accumulation of water in Chaohu basin under two kinds of rainfall intensity are simulated by the model of MIKE FLOOD.And the distribution of disaster vulnerability under the risk conditions are plotted.On the whole,the high vulnerability areas are mainly concentrated in the valley areas in the southwest mountain areas,the urban built-up areas in the central regions,paddy fields and dryland farming areas.The rural settlements and industrial land in the middle of the region are more vulnerable.Lakes and unused land in the east are least vulnerable.With the increase of rainfall intensity,the time of water accumulation appear in advance,and the submergence range and submerged depth also increase significantly.Therefore,the vulnerability of flood disaster is also increasing significantly.