Driven by climate change,extreme events such as floods are becoming increasingly frequent globally.To address the growing and dynamic flood risks and foster the development of resilient cities,the concept of urban flo...Driven by climate change,extreme events such as floods are becoming increasingly frequent globally.To address the growing and dynamic flood risks and foster the development of resilient cities,the concept of urban flood resilience has been increasingly applied to flood prevention.Investigating multi-scale responses of urban flood resilience to climate change can help policymakers develop multi-level enhancement pathways and concrete measures to enhance flood resilience,providing guidance for urban flood risk management.However,research in this field remains insufficient.Therefore,taking the Pearl River Delta(PRD)as the target area,this study applied the pressure-state-response(PSR)model and the extension catastrophe progression method to assess urban flood resilience in 2019 and 2070 under SSP1-2.6.From the perspectives of the city,economic circle,and urban agglomeration,the impacts of climate change on multi-scale urban flood resilience and multi-level enhancement pathways for flood resilience of the PRD were investigated.Results show that its response of flood resilience to climate change is most evident in Zhuhai and least evident in Shenzhen.Climate change exerts its strongest impacts on the flood resilience of the Shenzhen-Dongguan-Huizhou(SDH)economic circle and the weakest on the Guangzhou-Foshan-Zhaoqing economic circle.Across all scales,climate change impedes the maintenance of flood resilience in the PRD,even under a low-emission sustainable development scenario.This impact is more pronounced in highly urbanized areas than in less urbanized ones.Consequently,the PRD should establish a"top-down"multi-level approach of"highly urbanized areas—the SDH economic circle-Dongguan"for flood resilience enhancement.Strengthening the flood resilience of Dongguan is of significant importance for achieving the overall enhancement in the PRD under climate change.展开更多
Road networks are a critical infrastructure system for the sustainable functioning of cities.However,they are frequently disrupted by urban flooding,leading to increased travel times and hindering emergency responses....Road networks are a critical infrastructure system for the sustainable functioning of cities.However,they are frequently disrupted by urban flooding,leading to increased travel times and hindering emergency responses.This study proposed a novel dynamic flood–response simulation framework for urban transportation to evaluate the impacts of rainstorms and flooding on traffic systems,focusing on coupling the Integrated Hydrology and Hydrodynamics Urban Flood Model(IHUM)and the Simulation of Urban MObility(SUMO)model.The results obtained from Xiaoguwei Island,Guangzhou City,indicate that a 2-h rainstorm of a 2-year return period can affect traffic for over 4.5 h.During a 100-year return period rainstorm,average travel speed declines by 54%,while the emergency response time,for example,for police services,increases from 4.83 to 14.52 min.These findings highlight the significant impacts of flooding on urban traffic networks,assisting local authorities and stakeholders to proactively identify vulnerable network segments and prioritize targeted interventions for enhancing transportation system resilience to floods.展开更多
This study focused on the performance and limitations of the local inertial approximation form model(LIM)of the shallow water equations(SWEs)when applied in urban flood modeling.A numerical scheme of the LIM equations...This study focused on the performance and limitations of the local inertial approximation form model(LIM)of the shallow water equations(SWEs)when applied in urban flood modeling.A numerical scheme of the LIM equations was created using finite volume method with a first-order spatiotemporal Roe Riemann solver.A simplified urban stormwater model(SUSM)considering surface and underground dual drainage system was constructed based on LIM and the US Environmental Protection Agency Storm Water Management Model.Moreover,a complete urban stormwater model(USM)based on the SWEs with the same solution algorithm was used as the evaluation benchmark.Numerical results of the SUSM and USM in a highly urbanized area under four rainfall return periods were analyzed and compared.The results reveal that the performance of the SUSM is highly consistent with that of the USM but with an improvement in computational efficiency of approximately 140%.In terms of the accuracy of the model,the SUSM slightly underestimates the water depth and velocity and is less accurate when dealing with supercritical flow in urban stormwater flood modeling.Overall,the SUSM can produce comparable results to USM with higher computational efficiency,which provides a simplified and alternative method for urban flood modeling.展开更多
The integration of gray and green infrastructure has proven to be a feasible approach for managing stormwater in established urban areas.However,evaluating the specific contributions of such coupled strategies is chal...The integration of gray and green infrastructure has proven to be a feasible approach for managing stormwater in established urban areas.However,evaluating the specific contributions of such coupled strategies is challenging.This study introduced a novel integrated hydrological-hydrodynamic model that takes into account the layout of low-impact development(LID)facilities along with pipeline alignment and rehabilitation.Reliable results from modeling were used to assess the individual contribution of LID and improved drainage facilities to urban flooding mitigation.We selected a natural island in Guangzhou City,China,as the study site.The results indicate that combining three LID measures,namely green roofs,sunken green spaces,and permeable pavements,can reduce total runoff by 41.7%to 25.89%for rainfall recurrence periods ranging from 1year to 100 years,and decrease the volume of nodal overflow by nearly half during rainfall events of less than 10-year return period.By integrating LID measures with the upgraded gray infrastructure,the regional pipeline overloading condition is substantially alleviated,resulting in a significant improvement in pipeline system resilience.For urban flooding control,it is recommended to integrate sufficient green space and avoid pipe-laying structural issues during urban planning and construction.The findings may assist stakeholders in developing strategies to best utilize gray and green infrastructure in mitigating the negative eff ects of urban flooding.展开更多
The Pearl River Delta(PRD)is one of the three urban agglomerations in China that have experienced rapid development.For this study,a core area of the PRD was identified,comprising the highly urbanized areas of Guangzh...The Pearl River Delta(PRD)is one of the three urban agglomerations in China that have experienced rapid development.For this study,a core area of the PRD was identified,comprising the highly urbanized areas of Guangzhou,Foshan,Zhongshan,Zhuhai,Shenzhen,and Dongguan Cities.The expansion of these urban areas was tracked across three time periods—the year population urbanization rate exceeded 70%(2000),18 years before(1982),and 18 years after(2018).This study used the Weather Research and Forecasting(WRF)model to explore summer rainfall changes across different urbanization periods in the PRD core area.The results show that urban land expansion mainly occurred in the post urbanization period.Rainfall changes acros s different urbanization periods were roughly consistent with previously observed spatial and temporal changes accompanying urban expansion in the PRD core area.Extreme rainfall mainly increased in the post urbanization period,shifting rainstorm center towards the PRD core area.Further causal analysis revealed that land use changes affected rainfall by altering thermodynamics and water vapor transfer.The urban expansion changed the surface energy balance,resulting in increased surface heating and heat island effects.The heat island effects thickened the planetary boundary layer and increased vertical wind speeds,which initiated dry island effects,thereby causing more water vapor transportation to the atmosphere.Consequently,rainstorms and extreme rainfall events have become concentrated in urban areas.展开更多
文摘Driven by climate change,extreme events such as floods are becoming increasingly frequent globally.To address the growing and dynamic flood risks and foster the development of resilient cities,the concept of urban flood resilience has been increasingly applied to flood prevention.Investigating multi-scale responses of urban flood resilience to climate change can help policymakers develop multi-level enhancement pathways and concrete measures to enhance flood resilience,providing guidance for urban flood risk management.However,research in this field remains insufficient.Therefore,taking the Pearl River Delta(PRD)as the target area,this study applied the pressure-state-response(PSR)model and the extension catastrophe progression method to assess urban flood resilience in 2019 and 2070 under SSP1-2.6.From the perspectives of the city,economic circle,and urban agglomeration,the impacts of climate change on multi-scale urban flood resilience and multi-level enhancement pathways for flood resilience of the PRD were investigated.Results show that its response of flood resilience to climate change is most evident in Zhuhai and least evident in Shenzhen.Climate change exerts its strongest impacts on the flood resilience of the Shenzhen-Dongguan-Huizhou(SDH)economic circle and the weakest on the Guangzhou-Foshan-Zhaoqing economic circle.Across all scales,climate change impedes the maintenance of flood resilience in the PRD,even under a low-emission sustainable development scenario.This impact is more pronounced in highly urbanized areas than in less urbanized ones.Consequently,the PRD should establish a"top-down"multi-level approach of"highly urbanized areas—the SDH economic circle-Dongguan"for flood resilience enhancement.Strengthening the flood resilience of Dongguan is of significant importance for achieving the overall enhancement in the PRD under climate change.
基金supported by the National Natural Science Foundation of China(Grant No.52279015)the State Key Laboratory of Subtropical Building and Urban Science(Grant No.2023ZA01)+1 种基金the Department of Education of Guangdong Provincethe UK-China Institutional Partnership Exploration Fund by the British Council(Grant No.6).
文摘Road networks are a critical infrastructure system for the sustainable functioning of cities.However,they are frequently disrupted by urban flooding,leading to increased travel times and hindering emergency responses.This study proposed a novel dynamic flood–response simulation framework for urban transportation to evaluate the impacts of rainstorms and flooding on traffic systems,focusing on coupling the Integrated Hydrology and Hydrodynamics Urban Flood Model(IHUM)and the Simulation of Urban MObility(SUMO)model.The results obtained from Xiaoguwei Island,Guangzhou City,indicate that a 2-h rainstorm of a 2-year return period can affect traffic for over 4.5 h.During a 100-year return period rainstorm,average travel speed declines by 54%,while the emergency response time,for example,for police services,increases from 4.83 to 14.52 min.These findings highlight the significant impacts of flooding on urban traffic networks,assisting local authorities and stakeholders to proactively identify vulnerable network segments and prioritize targeted interventions for enhancing transportation system resilience to floods.
基金supported by the National Natural Science Foundation of China(Grant Numbers 51739011 and 51879108)。
文摘This study focused on the performance and limitations of the local inertial approximation form model(LIM)of the shallow water equations(SWEs)when applied in urban flood modeling.A numerical scheme of the LIM equations was created using finite volume method with a first-order spatiotemporal Roe Riemann solver.A simplified urban stormwater model(SUSM)considering surface and underground dual drainage system was constructed based on LIM and the US Environmental Protection Agency Storm Water Management Model.Moreover,a complete urban stormwater model(USM)based on the SWEs with the same solution algorithm was used as the evaluation benchmark.Numerical results of the SUSM and USM in a highly urbanized area under four rainfall return periods were analyzed and compared.The results reveal that the performance of the SUSM is highly consistent with that of the USM but with an improvement in computational efficiency of approximately 140%.In terms of the accuracy of the model,the SUSM slightly underestimates the water depth and velocity and is less accurate when dealing with supercritical flow in urban stormwater flood modeling.Overall,the SUSM can produce comparable results to USM with higher computational efficiency,which provides a simplified and alternative method for urban flood modeling.
基金supported by the State Key Laboratory of Subtropical Building and Urban Science(Grant No.2023ZA01)the Science and Technology Program of Guangzhou,China(Grant No.202201010271)the National Natural Science Foundation of China(Grant No.52109018)。
文摘The integration of gray and green infrastructure has proven to be a feasible approach for managing stormwater in established urban areas.However,evaluating the specific contributions of such coupled strategies is challenging.This study introduced a novel integrated hydrological-hydrodynamic model that takes into account the layout of low-impact development(LID)facilities along with pipeline alignment and rehabilitation.Reliable results from modeling were used to assess the individual contribution of LID and improved drainage facilities to urban flooding mitigation.We selected a natural island in Guangzhou City,China,as the study site.The results indicate that combining three LID measures,namely green roofs,sunken green spaces,and permeable pavements,can reduce total runoff by 41.7%to 25.89%for rainfall recurrence periods ranging from 1year to 100 years,and decrease the volume of nodal overflow by nearly half during rainfall events of less than 10-year return period.By integrating LID measures with the upgraded gray infrastructure,the regional pipeline overloading condition is substantially alleviated,resulting in a significant improvement in pipeline system resilience.For urban flooding control,it is recommended to integrate sufficient green space and avoid pipe-laying structural issues during urban planning and construction.The findings may assist stakeholders in developing strategies to best utilize gray and green infrastructure in mitigating the negative eff ects of urban flooding.
基金supported by the National Natural Science Foundation of China(Grant No.52279015)。
文摘The Pearl River Delta(PRD)is one of the three urban agglomerations in China that have experienced rapid development.For this study,a core area of the PRD was identified,comprising the highly urbanized areas of Guangzhou,Foshan,Zhongshan,Zhuhai,Shenzhen,and Dongguan Cities.The expansion of these urban areas was tracked across three time periods—the year population urbanization rate exceeded 70%(2000),18 years before(1982),and 18 years after(2018).This study used the Weather Research and Forecasting(WRF)model to explore summer rainfall changes across different urbanization periods in the PRD core area.The results show that urban land expansion mainly occurred in the post urbanization period.Rainfall changes acros s different urbanization periods were roughly consistent with previously observed spatial and temporal changes accompanying urban expansion in the PRD core area.Extreme rainfall mainly increased in the post urbanization period,shifting rainstorm center towards the PRD core area.Further causal analysis revealed that land use changes affected rainfall by altering thermodynamics and water vapor transfer.The urban expansion changed the surface energy balance,resulting in increased surface heating and heat island effects.The heat island effects thickened the planetary boundary layer and increased vertical wind speeds,which initiated dry island effects,thereby causing more water vapor transportation to the atmosphere.Consequently,rainstorms and extreme rainfall events have become concentrated in urban areas.
