| Global urbanization occurs rapidly,which increases the risk of floods,droughts.under background of global change,and results in environmental degradation.Among all natural disasters that threaten human society,flood hazards may be the most destructive and frequent.China is a high-risk and flood-prone area with flood disasters of varying degrees occurring almost every year.Flood disasters are major natural disasters affecting two-thirds of China,50% of the population and 70% of property.Severe urban flooding is expected to occur more frequently in cities in the future because of ongoing global climate change and accelerated urbanization.Urban flooding has become an important issue affecting city security and sustainable development of China.As an important support for the economic development of northeast China,the central and southern Liaoning urban agglomeration has made outstanding contributions to the economic development of northeast China and even the whole country.With the high concentration of urban population,economy and buildings,urban flooding has become more prominent and the risk of inundation has become more severe.In this study,south-central Liaoning urban agglomeration is taken as an example,and natural and socio-economic conditions are considered.Based on the theory of surface hydrological process and disaster risk assessment,the urban flooding process model and comprehensive risk assessment model were constructed to evaluate the urban storm flooding process and comprehensive risk characteristics under different rainfall return periods.Based on the,the flooding prevention and control strategies are proposed to provide theoretical basis and suggestions for the flooding prevention and control and sustainable development of the central and southern Liaoning urban agglomeration.The main research contents and conclusions of this thesis are as follows:(1)Stagnation processes and flow-sink processes were analyzed.Based on ArcGIS platform,the UGI storage capacity and sink production capacity of the study area were calculated.The results show that the UGI with good storage capacity are mainly located in the periphery of the city,while the storage capacity in the core area of the city is poor.In addition,the rainwater storage capacity of UGI has obvious advantages under 10 a rainfall conditions.With the increase of rainfall,the canopy retention and soil infiltration capacity of UGI gradually reach saturation effect and cannot function in a short period of time.The yield rate is positively correlated with the rainfall recurrence period,i.e.,it increases with the increase of rainfall recurrence period,and the yield rate of different recurrence periods shows a trend of stable growth.(2)Spatial characteristics of urban flooding were analyzed.The results show that with the increase of rainfall return period from 10 a to 100 a,the depth of flooding in the same sub-catchment increases continuously.Under the same rainfall conditions,the depth of flooding in different areas also has significant differences,and the depth of urban flooding decreases from the core to the peripheral areas of the city.The areas with serious flooding are mainly concentrated in road intersections and their surrounding residential neighborhoods,urban villages and old neighborhoods.In addition,according to the results of Moran’s I index,urban flooding events in the central and southern Liaoning urban agglomeration have significant spatial clustering characteristics and most urban cores are dominated by high-high and low-low clusters.(3)Comprehensive risk assessment of flooding based on AHP and entropy method.Based on the theory of hazard,exposure and vulnerability of disaster system and disaster prevention and mitigation capacity("H-E-V-R"),a weighting method combining AHP and entropy weighting method was used to assess the comprehensive flooding risk in the south-central Liaoning urban cluster.The results show that the comprehensive risk of urban storm flooding has significant spatial heterogeneity,the composition of risk indicators is obviously different in different cities,the comprehensive risk of storm flooding is higher in Shenyang and Dalian than in other cities,and there is consistency in the spatial distribution characteristics of comprehensive risk and urban flooding events. |
