A cascading failure of landslide dams caused by strong earthquakes or torrential rains in mountainous river valleys can pose great threats to people’s lives,properties,and infrastructures.In this study,based on the t...A cascading failure of landslide dams caused by strong earthquakes or torrential rains in mountainous river valleys can pose great threats to people’s lives,properties,and infrastructures.In this study,based on the three-dimensional Reynoldsaveraged Navier-Stokes equations(RANS),the renormalization group(RNG)k-εturbulence model,suspended and bed load transport equations,and the instability discriminant formula of dam breach side slope,and the explicit finite volume method(FVM),a detailed numerical simulation model for calculating the hydro-morphodynamic characteristics of cascading dam breach process has been developed.The developed numerical model can simulate the breach hydrograph and the dam breach morphology evolution during the cascading failure process of landslide dams.A model test of the breaches of two cascading landslide dams has been used as the validation case.The comparison of the calculated and measured results indicates that the breach hydrograph and the breach morphology evolution process of the upstream and downstream dams are generally consistent with each other,and the relative errors of the key breaching parameters,i.e.,the peak breach flow and the time to peak of each dam,are less than±5%.Further,the comparison of the breach hydrographs of the upstream and downstream dams shows that there is an amplification effect of the breach flood on the cascading landslide dam failures.Three key parameters,i.e.,the distance between the upstream and the downstream dams,the river channel slope,and the downstream dam height,have been used to study the flood amplification effect.The parameter sensitivity analyses show that the peak breach flow at the downstream dam decreases with increasing distance between the upstream and the downstream dams,and the downstream dam height.Further,the peak breach flow at the downstream dam first increases and then decreases with steepening of the river channel slope.When the flood caused by the upstream dam failure flows to the downstream dam,it can produce a surge wave that overtops and erodes the dam crest,resulting in a lowering of the dam crest elevation.This has an impact on the failure occurrence time and the peak breach flow of the downstream dam.The influence of the surge wave on the downstream dam failure process is related to the volume of water that overtops the dam crest and the erosion characteristics of dam material.Moreover,the cascading failure case of the Xiaogangjian and Lower Xiaogangjian landslide dams has also been used as the representative case for validating the model.In comparisons of the calculated and measured breach hydrographs and final breach morphologies,the relative errors of the key dam breaching parameters are all within±10%,which verify the rationality of the model is applicable to real-world cases.Overall,the numerical model developed in this study can provide important technical support for the risk assessment and emergency treatment of failures of cascading landslide dams.展开更多
As sea level rises,low-lying coastal cites face increasing threat of flood disruption,particularly in terms of human mobility.Commuters are vulnerable to bad weather,as it is difficult to cancel trips even in extreme ...As sea level rises,low-lying coastal cites face increasing threat of flood disruption,particularly in terms of human mobility.Commuters are vulnerable to bad weather,as it is difficult to cancel trips even in extreme weather conditions.Using Shanghai's automobile commuting population as an example,we categorized commuters by travel distance and income level to assess disruptions and delays due to floods,considering future sea level rise.The results show that local flooding disrupts commuting patterns by affecting roadways,with disruption decreasing with distance from the flooded area.This offers a mobility perspective on the indirect impacts of floods.During baseline flood events,long-distance commuters and the lowincome group are most affected,while short-distance commuters and the high-income group are less impacted.As sea level rises,floods will threaten all commuting groups,especially the high-income group.Using inaccessibility-commuting delay bivariate maps,this study revealed how socioeconomic differences impact mobility recovery after floods under climate change.The research highlights the differential impacts of floods on various socioeconomic groups in the context of climate change,offering insights for future urban planning and disaster mitigation strategies.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant Nos.U22A20602,U2040221).
文摘A cascading failure of landslide dams caused by strong earthquakes or torrential rains in mountainous river valleys can pose great threats to people’s lives,properties,and infrastructures.In this study,based on the three-dimensional Reynoldsaveraged Navier-Stokes equations(RANS),the renormalization group(RNG)k-εturbulence model,suspended and bed load transport equations,and the instability discriminant formula of dam breach side slope,and the explicit finite volume method(FVM),a detailed numerical simulation model for calculating the hydro-morphodynamic characteristics of cascading dam breach process has been developed.The developed numerical model can simulate the breach hydrograph and the dam breach morphology evolution during the cascading failure process of landslide dams.A model test of the breaches of two cascading landslide dams has been used as the validation case.The comparison of the calculated and measured results indicates that the breach hydrograph and the breach morphology evolution process of the upstream and downstream dams are generally consistent with each other,and the relative errors of the key breaching parameters,i.e.,the peak breach flow and the time to peak of each dam,are less than±5%.Further,the comparison of the breach hydrographs of the upstream and downstream dams shows that there is an amplification effect of the breach flood on the cascading landslide dam failures.Three key parameters,i.e.,the distance between the upstream and the downstream dams,the river channel slope,and the downstream dam height,have been used to study the flood amplification effect.The parameter sensitivity analyses show that the peak breach flow at the downstream dam decreases with increasing distance between the upstream and the downstream dams,and the downstream dam height.Further,the peak breach flow at the downstream dam first increases and then decreases with steepening of the river channel slope.When the flood caused by the upstream dam failure flows to the downstream dam,it can produce a surge wave that overtops and erodes the dam crest,resulting in a lowering of the dam crest elevation.This has an impact on the failure occurrence time and the peak breach flow of the downstream dam.The influence of the surge wave on the downstream dam failure process is related to the volume of water that overtops the dam crest and the erosion characteristics of dam material.Moreover,the cascading failure case of the Xiaogangjian and Lower Xiaogangjian landslide dams has also been used as the representative case for validating the model.In comparisons of the calculated and measured breach hydrographs and final breach morphologies,the relative errors of the key dam breaching parameters are all within±10%,which verify the rationality of the model is applicable to real-world cases.Overall,the numerical model developed in this study can provide important technical support for the risk assessment and emergency treatment of failures of cascading landslide dams.
基金supported by the National Natural Science Foundation of China(Grant No.42371088)the China National Key R&D Program(Grant No.2023YFF0807000)the China Postdoctoral Science Foundation(Grant No.2024M763185)。
文摘As sea level rises,low-lying coastal cites face increasing threat of flood disruption,particularly in terms of human mobility.Commuters are vulnerable to bad weather,as it is difficult to cancel trips even in extreme weather conditions.Using Shanghai's automobile commuting population as an example,we categorized commuters by travel distance and income level to assess disruptions and delays due to floods,considering future sea level rise.The results show that local flooding disrupts commuting patterns by affecting roadways,with disruption decreasing with distance from the flooded area.This offers a mobility perspective on the indirect impacts of floods.During baseline flood events,long-distance commuters and the lowincome group are most affected,while short-distance commuters and the high-income group are less impacted.As sea level rises,floods will threaten all commuting groups,especially the high-income group.Using inaccessibility-commuting delay bivariate maps,this study revealed how socioeconomic differences impact mobility recovery after floods under climate change.The research highlights the differential impacts of floods on various socioeconomic groups in the context of climate change,offering insights for future urban planning and disaster mitigation strategies.
