Urban flooding restructures mobility through coupled behavioral and network disruption: A systematic review of evidence

Uncertainties of urban flood modeling: Influence of parameters for different underlying surfaces

Effects of urban drainage inlet layout on surface flood dynamics and discharge

Flash floods in Mediterranean regions pose significant threats to lives, infrastructures, and economies. Recent episodes of extreme rainfall in one such region led to devastating flash floods, resulting in loss of life, destruction of homes, and widespread disruption of transportation networks. Therefore, there is a critical need for advanced methods to monitor and analyze the flood dynamics, especially in urban areas. This study investigates the use of two advanced image-based techniques, Fudaa-LSPIV (Coz et al., 2014) and SSISM-Flow (Ljubičić et al., 2024) for surface velocity and discharge estimation of urban flash floods. The research used videos or images of historical urban flood events and estimated the surface velocity. To analyze the urban floods, Matera, a city of southern Italy, was selected as case study. Matera was chosen because its historical city center, the “Sassi”, was affected by extreme rainfall events in the last few years, e.g. 2014, 2018, 2019, and 2023. Five extreme past flood events occurred on 3 Aug 2018, 12 Nov 2019, 2 Jun 2023, and 2 & 21 July 2024 were recorded for estimation of surface velocity. Fudaa-LSPIV works according to the Particle Image Velocimetry (PIV) principles, while SSISM-Flow is a user-friendly and Python-based innovative tool with OpenCV integration for precise surface velocity filed extraction. These methods involve steps such as image stabilization, camera calibration, orthorectifications, and velocity calculation. Both techniques were evaluated based on their accuracy, performance, and application to overcome the limitations of analyzing the surface flow of urban floods. This study is innovative in comparing methods to estimate surface velocity of real-time flash floods in urban areas. Using these techniques, the surface velocities were estimated along key transects, and results were cross-validated using the Float Time method as benchmark. The outcomes of both approaches turned out to be consistent with benchmark data, confirming their reliability in monitoring urban floods. This comprehensive flow analysis provided insights for calibrating flood models and enhanced risk management. This study introduced a novel application of these techniques in real-time urban flood monitoring. Furthermore, it contributes to the development of an early warning system, enhances management strategies, and mitigates flood risks in vulnerable areas.ReferenceLjubičić, R., et al., 2024.  SSIMS-flow: image velocimetry workbench for open-channel flow rate estimation. Environ. Model. Softw. 173, 105938.Coz, Jérôme Le, wt al., 2014. Image-Based Velocity and Discharge Measurements in Field and Laboratory River Engineering Studies Using the Free Fudaa-LSPIV Software. In Proc.of the Inter.  Conf. on Fluvial Hydraulics, River Flow, 1961–67.AcknowledgmentsThis work was funded by the Next Generation EU - Italian NRRP, Mission 4, Component 2, Investment 1.5, call for the creation and strengthening of 'Innovation Ecosystems', building 'Territorial R&D Leaders' (Directorial Decree n. 2021/3277) - project Tech4You - Technologies for climate change adaptation and quality of life improvement, n. ECS0000009. This work reflects only the authors’ views and opinions, neither the Ministry for University and Research nor the European Commission can be considered responsible for them.

A flood vulnerability assessment of the City of Tucson, Arizona’s transportation systems was conducted with special reference to low-income and minority neighborhoods. Short-term flooding from extreme storm events pose a serious challenge to transportation system reliability and emergency response in cities across the United States. This problem, which is anticipated to grow over the next century due to climate change, is often hardest on vulnerable populations, including low-income and minority neighborhoods. Our work aimed to advance national research methods for assessing multi-modal transportation degradation due to flooding. We identified priority locations for Tucson to make transportation improvement investments for the purpose of mitigating urban transportation system flooding. This included increasing equitable accessibility to the multi-modal transportation network across three modes: vehicular, bicycle, and public transportation via pedestrian access to bus stops. As a case study, our proposal has national flood hazard transportation vulnerability and equity implications. The project had three stages. In Stage 1 we estimated flood conditions based on a 5-year, 1-hour storm event with FLO-2D and a digital elevation model (DEM) constructed using LiDAR data. In Stage 2 we analyzed neighborhood transportation vulnerability based on overall transportation system performance and use across the three transportation networks. In Stage 3, we performed thirty (the top ten sites for the three modes of transportation) green infrastructure (GI) scenario analyses to determine the impact that GI implementations could have on the multimodal system. Of the thirty areas studied, 93% were part of census tracts with median household incomes below the Tucson average. We found that GI implementation performs most effectively to increase multi-modal access when implemented in moderate flooding conditions. In extreme cases, comprehensive, neighborhood-scale GI implementation did not result in creating greater accessibility during flood events. Rather than municipalities selecting areas for GI implementation that have the highest volumes of flooding or citizen complaints, GI implementation funds may be invested in moderate flooded area for greatest improvement of multimodal access. Future research will assess impact across time durations (rather than simple peak event calculations) and work to optimize GI implementation across multiple benefits for multiple modes of transportation (rather than individual modes). We plan to communicate our findings broadly. This research is a proof of concept for a larger, long-term project to advance national research methods to reduce the impact of chronic flooding on the multi-modal transportation network. Additional funding from NITC and other sources is currently being targeted.

This paper summarizes research on the effects of rail transit on the performance of transportation systems in major U.S. cities. It summarizes results from the study Rail Transit In America: Comprehensive Evaluation of Benefits, which evaluates rail transit benefits on the basis of comparison of transportation system performance in major U.S. cities. It finds that cities with larger, well-established rail systems have significantly higher per capita transit ridership, lower average per capita vehicle ownership and mileage, less traffic congestion, lower traffic death rates, and lower consumer transportation expenditures than otherwise comparable cities. These findings indicate that rail transit systems can provide a variety of economic, social, and environmental benefits and that benefits tend to increase as a system expands and matures.

On the distribution of urban road space for multimodal congested networks

Urban flood hazard is a typical natural disaster that occurs due to the reduction of permeable surfaces as a result of land use conversion and changes in rainfall intensity. It ensures the need of different mitigation strategies such as sufficient drainage system, and it is a simple mitigation measure that can be applied in the ground. This paper is timely due to the lack of research studies undertaken that are related to the study area. Natural disasters, flood hazard, influence of urbanization for urban flood, and negative influence of urban flood in the context of the world and Asian region have been discussed in the available literature. Limited research has been undertaken on urban flood mitigation based on hydrological analysis and run off volume calculation in Kaduwela Municipal Council (KMC) area. With this limitation, this paper focuses on analysing the runoff rainwater volume to mitigate urban flood in 2030 (predicted land use) by calculating the rainwater volume in natural and artificial possible outfalls of each watersheds in KMC. The analysis consists of three phases such as: land use prediction, hydrological analysis, and calculation. A GIS-based land use prediction is simulated to analyse the land use changes in relation to green, blue, and brown fills. The revealed land use conversion is also processing day by day as a result of land use conversion and rapid urbanization which will increase the runoff volume in 2030. A GISbased Hydrological analysis was carried out to identify the outfalls and watersheds of the study area. The possible outfalls function as outlets of runoff water which were collected in each watershed. Runoff volume was calculated by using rational formula (Q = 0.0028CIA) and the parameters of the equation used were the coefficient of land use in 2030, rainfall intensity, and 90 acres portion of the watersheds. A sufficient drainage system was also designed to make KMC a disaster resilient municipality. This research will be important in the process of decision-making and policy implementation in the fields of urban planning and flood mitigation.

Understanding and managing disaster evacuation on a transportation network

Integrated urban and riverine flood risk management in the Fujiang River Basin-Mianyang city

With global climate change and rapid urbanization, it is critical to assess urban flood resilience (UFR) within the social-economic-natural complex ecosystem in dealing with urban flood disasters. This research proposes a conceptual framework based on the PSR-SENCE model for evaluating and exploring trends in urban flood resilience over time, using 27 cities in the Yangtze River Delta (YRD) of China as case studies. For the overall evaluation, a hybrid weighting method, VIKOR, and sensitivity analysis were used. During that time, UFR in the YRD region averaged a moderate level with an upward trend. This distinguishes between the resilience levels and fluctuation trends of provinces and cities. Jiangsu, Zhejiang, and Anhui provinces all displayed a trend of progressive development; however, Shanghai displayed a completely opposite pattern, mainly because of resilience in the state dimension. During that time, 81.41% of cities exhibited varying, upward trends in urban flood resistance, with few demonstrating inverse changes. Regional, provincial, and city-level implications are proposed for future UFR enhancement. The research contributes to a better understanding of the urban complex ecosystem under flood conditions and provides significant insights for policymakers, urban planners, and practitioners in the YRD region and other similar flood-prone urban areas.

Evaluating climate change adaptation policies for urban transportation in India

Located by Nha Be River and within 30 km of the South China Sea, the Nha Be District is one of the outer districts of Ho Chi Minh City that has suffered severe urban flooding. For a comprehensive understanding of urban floodingUrban flooding in this district within the larger context of global climate change, this quantitative study aims to describe the frequency, intensity, and impacts of floods on the locals as well as summarize multi-scale responses. In surveying 210 households in the Nha Be District, and by conducting 14 in-depth interviews with community representatives andLandmanagement land managementLand management officers, the study found that rapid urbanization and climate variability in the last ten years have contributed to the complexity of flooding in this area, which is characterized by low-lying terrain and an interlocking waterway system. Among the surveyed households, half of them have frequently faced flooding throughout the year, and 39.4% of them have been impacted at one time. Flood intensity is variable, with the average depth at approximately 20 cm. Since flooding has negatively influenced living quality, commuting, and housing quality, several solutions have been implemented by homeowners, the community, and the local government to cope with the growing impacts of flooding. Despite certain approaches taken by different stakeholders, it is critical to propose further approaches for dealing with urban floodingUrban flooding in Nha Be District. These approaches might take into account the solutions relating to flood-proof housing and urbanHousing and urban settlements areas in response to urban floodingUrban flooding in the context of climate change.

Urban flooding is an escalating threat driven by climate change, rapid urbanization, and altered land use patterns, resulting in increased impervious surfaces and disrupted hydrological cycles. Globally, flood risks have intensified due to rising temperatures and shifting precipitation patterns. Urban populations continue to grow, increasing the vulnerability and exposure of cities to flood hazards. In India, urban centers face frequent flood disasters with significant economic and social impacts. This study reviews recent advances in urban flood modeling, focusing on climatic and land-use influences, with applications of models such as PCSWMM, HEC-HMS, and coupled 1D-2D hydrodynamic approaches. Climate scenarios from IPCC’s latest reports and urban growth projections are integrated to assess future flood risks. Additionally, flood mitigation strategies, including Low Impact Development (LID) practices like detention ponds, permeable pavements, and green roofs, are evaluated for their effectiveness in reducing flood peaks and volumes. Case studies from Indian cities demonstrate the critical need for sustainable urban water management and adaptive infrastructure to enhance resilience against the increasing threat of urban floods induced by climatic and anthropogenic factors.

Depth prediction of urban flood under different rainfall return periods based on deep learning and data warehouse.

Urban flood risk warning under rapid urbanization