| Since the Industrial Revolution,estuarine cities located at the land-sea-river interface have grown rapidly,with high densities of population and economic activity.However,global climate change due to increasing greenhouse gases has exposed estuarine cities to unprecedented weather extremes and abnormal flooding beyond natural variability.In addition,the superposition of ground subsidence and sea level rise,the rapid urbanization triggering the reduction of natural water surface and infiltration difficulties,will aggravate the hazards of typhoon storm surge and flooding,affecting the production and living safety of estuarine city residents.The waterfront areas of estuarine cities are the most sensitive and vulnerable to flooding and are directly exposed to sthe ignificant and spatially non-homogeneous distribution of flood risks.How to reduce flood risks through collaborative planning of blue-green space in urban waterfront space is the basis of urban resilience construction.In this paper,we firstly combine the facts of climate change in estuarine cities and the characteristics of flood risk in waterfront space to establish the goal of climate change and flood adaptation in estuarine cities;secondly,we establish the methodological system of blue-green collaborative resilient flood adaptation planning in estuarine cities based on the investigation of flood risk background information,identification of risk characteristics and risk assessment;finally,we take the waterfront space of Huangpu River in Shanghai as the case object,and through the risk zoning the of waterfront area,catchment system model Finally,using the Shanghai Huangpu River waterfront space as a case study,we identified flood risks,implemented rainfall reduction,and ensured water safety through waterfront risk zoning,catchment system modeling,and coordinated blue-green update control to promote sustainable development of the urban waterfront.The main conclusions are as follows.(1)Construction of a collaborative blue-green resilient flood planning method system for the estuarine urban waterfrontCombining the investigation of flood risk background information in estuarine urban waterfront,risk characteristics identification,risk assessment,and multi-scale transmission of blue-green synergy,the network nested relationship of"macro-city scale-meso-waterfront scale-micro-site scale",scale The network nesting relationship of"macro-city scale-meso-waterfront scale-micro-site scale",scale conduction relationship and flood adaptation objectives at different levels are established to build a flood resilience system for estuarine urban waterfront space.Firstly,the macroscopic scale uses hazard,vulnerability,and exposure as the criterion layer to build the evaluation index system,and uses scenario simulation and spatial overlay to identify the spatial distribution of the flood risk index,and the scale unit is ten/hundred/thousand km~2 to solve the problem of urban scale flood suitability.The water surface rate is set according to the catchment area to achieve the convergence and volume of flooding,and the scale unit is taken as a unit of ten/hundred hm~2 to solve the problem of water security at the catchment scale;at the microscopic scale,the water surface rate design target is established for the mesoscopic scale,and the rainfall control is realized through the water surface rate and rainwater infrastructure synergy,and the front-end,middle-end and end-end organization of the water body are used to design flood regulation and detention.The design of flood regulation and detention space,clear feasibility of rainwater control,scale unit in hundred/thousand/million m~2,solve the problem of rainwater reductithe on at microscopic site scale.(2)Flood risk assessment and zoning measures for the Huangpu River waterfront in the estuary city of ShanghaiBased on the IPCC definition of risk,a flood risk index assessment model is constructed according to hazard,vulnerability,and exposure,11 evaluation indexes are selected,and the flood risk index is calculated by the method of scenario simulation and GIS spatial overlay.The spatial pattern of flood risk in the Huangpu River waterfront area of Shanghai under the climate change target is obtained based on the evaluation results by using the scenario simulation with 2030,205,0 and 2100 as the time points.The spatial pattern of flood risk in Shanghai’s Huangpu River waterfront under the climate change target was obtained based on the evaluation results.The results show that the floodplain is located in the east of Baoshan District and the northwest corner of Pudong New Area,and the waterfront space adopts the strategy of retreating and evacuating,implementing the"estuary protection plan",and constructing ecological wetlands in the upstream Qingpu and Songjiang Districts;the flood-resistant zone is located in the central city,and the risk of waterfront space is expanding,so it adopts the strategy of resistance;the flood-bearing zone adopts the strategy of coexistence wita h flood,but its potential is decreasing.The flood-bearing area adopts the strategy of living with floods,but its potential is decreasing.(3)Flood-bearing area of the Huangpu River is a synergistic flood management model of the blue-green space of the catchment systemBased on the macro-scale adaptation to climate change,we further analyze the adaptation and renewal strategies of flood-bearing areas on the waterfront at the mesoscopic scale.Based on the RIDEM model,D8 algorithm,and basin tool,the primary and secondary catchment areas are divided and the catchment zones are extracted and calculated,and the flood-bearing capacity before and after the design is calculated according to the volume method and the possibility of coexistence with the flood is judged.The relationship between the catchment capacity and flood risk of a specific site is measured according to different substrates and drainage coeffi,ands;and the feasibility of the 10 primary catchment samples in future flooding scenarios is analyzed.The results show that the water surface ratio of the sample sites J(development area)and J(development area)were adjusted.The results show that sample sithe te J(industrial base of the development zone)faces great flooding risk in the future and may lead to serious loss of life and property as an industrial development site in the planning guidelines,so it is recommended to control the development or plan as an ecological reserve;sample sites G,H and I(Pujiang Country Park area)face relatively low flooding risk in the future and can be planned as industrial development sites in the development zone.(4)Site catchment system blue-green infrastructure planning and controlBased on macroscopic risk zoning and mesoscopic catchment system model calculation,we conduct the site scale to realize blue-green cooperative update control.Around the design water surface rate and waterfront vegetation buffer zone planning index,calculate the increase of water surface rate,design the storage volume,through the water surface rate and rainwater infrastructure synergy to achieve rainwater flood control.The stormwater infrastructure is divided into regulating and detention types according to the flooding adaptation function,and the specific organization of different functions is studied,and how to achieve stormwater reduction is analyzed by front-end,middle-end and end-end,and the waterfront vegetation buffer zone is planned to promote the sustainable development of the site and its ponds.From the perspective of micro-renewal of the site,the method and location selection process of increasing the water surface rate according to the digital water system are proposed in the site design,and the specific spatial location of the water surface of the site is determined by Grasshopper software;the designed water surface rate and the waterfront vegetation buffer zone under the flood-bearing goal are planned in cooperation with the blue-green space to achieve the rainfall control and water safety goal. |
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