Technological evolution survey allowed the broad use of 2D mathematical models for flood simulation. However, it is possible that the answer required for a given problem does not need a 2D approximation or even does not configure a 2D surface solution. Urban flood simulations may fall in this second case, since urban structures may interact with flood flows and introduce discontinuities in the surface solution. This study aims to highlight the discussion about the physical interpretation and the modeller role as key elements in the interpretation and representation of physical systems. To support this proposal, the MODCEL, a Quasi-2D flow-cell model, was used in two different ways: in a detailed raster approach, similarly to usual 2D model uses; and in an alternative conceptual and interpretive way, using larger cells representing homogeneous portions of the territory. The modelling results showed that equivalent responses can be obtained. Although other models can be used and could offer different absolute results, the relative analysis offered sufficient support to the research hypothesis that a physical-based process conducted by a conscient modeller is crucial for model reliability and optimization.

Urban flooding is a growing concern, particularly in coastal lowland cities where climate change exacerbates hazards through rising sea levels and intense rainfall. Traditional flood defenses like fluvial polders often exacerbate urban fragmentation and maintenance costs if poorly integrated into planning. This study proposes a multifunctional assessment design framework to evaluate polder design effectiveness considering both the hydraulic and social–environmental dimensions, emphasizing blue–green infrastructure (BGI) for flood control, leisure, and landscape integration. Three design scenarios for Rio de Janeiro’s Jardim Maravilha neighborhood were modeled hydrodynamically: S1 (dike near urban areas, pump-dependent) and S2/S3 (dikes along the riverbank, gravity-driven). Results show S2/S3 outperformed S1 in storage capacity (2.7× larger volume), freeboard resilience (0.42–0.43 m vs. 0.25 m), and urban integration (floodable parks accessible to communities), though S1 had faster reservoir emptying. Under climate change, all scenarios sustained functionality, but S1’s freeboard reduced by 86%, nearing its limit. The framework’s standardized scoring system balanced quantitative and qualitative criteria, revealing trade-offs between hydraulic efficiency and urban adaptability. The optimized S3 design, incorporating external storage and dredging, achieved the best compromise. This approach aids decision-making by systematically evaluating resilience, operational feasibility, and long-term climate adaptation, supporting sustainable flood infrastructure in coastal cities.

Risk can be defined as the relationship between the likelihood of a hazard causing a potential disaster and its consequences. This study aims to assess the likelihood that a new industrial region, located in the state of São Paulo (Brazil), will be flooded, causing the disruption of the mobility system and local economic activities. To fulfill this aim, a new approach is proposed by combining the vector information of the highway network that serves the region with the result of a quasi 2-D raster flood model, generating a set of interpreting rules for classifying the safety of routes. The model called MODCEL is a quasi-2D hydrodynamic model that represents the watershed using compartments called cells, and it was adapted to work using a raster file format in which each pixel is represented as a flow cell connected to its surroundings by the Saint-Venant equations without the inertia terms. Therefore, this study proposes an assessment framework that can be replicated for similar problems of flood risks to mobility. The possible effects of flood events on the accessibility to areas of interest are determined, indicating a possible disruption to economic activities and transportation and allowing for planning alternatives in advance.

Rapid global urbanization has intensified challenges related to unplanned growth, inefficient land use, and increased flood risk. Flood impacts, exacerbated by urban densification and land-use change, currently threaten approximately 1.81 billion people worldwide, affecting infrastructure, ecosystems, and human lives. This context highlights the need to integrate urban and environmental planning through sustainable approaches. Nature-based solutions and blue-green infrastructure offer strong potential to enhance urban flood resilience by combining ecological and hydraulic functions, while delivering co-benefits such as biodiversity enhancement, microclimate regulation, and improved urban livability. Aligning urban development with natural processes is particularly critical in vulnerable areas where conventional drainage systems are under pressure. In response, this study proposes an integrated environmental-urban diagnostic methodology that defines objective functions, identifies priority intervention areas, clarifies the role of each drainage project, and enables the measurement and comparison of intervention efficiency for flood risk reduction. Designed to be quantitative, accessible, and adaptable, the framework bridges scientific knowledge and municipal decision-making. The methodology was tested in Maricá (Rio de Janeiro, Brazil), focusing on the Bambu River basin, demonstrating its effectiveness in supporting integrated, resilient, and sustainable urban flood management.

The identification of areas prone to the occurrence of natural disasters is an important information, especially in urban areas. Therefore, this study aimed to propose a methodology for debris flow risk assessment, considered as one of the natural disasters that most cause deaths and material losses. To this end, this study made the slope stability modelling directly in a GIS software, in which the Infinite Slope Model was used for the slope stability calculation, and the SCS CN Method, as the infiltration model. For the risk assessment, Risk is defined by the product of the probability of the occurrence of a debris flow event (Hazard), where the influence of the environment’s physical characteristics and its triggering process are evaluated; with the severity of its consequences, measured in terms of the affected population (Exposure) and its weaknesses (Vulnerability).