Flood risk behaviors of United States riverine metropolitan areas are driven by local hydrology and shaped by race.

Knighton J ，Hondula K ，Sharkus C ，Guzman C ，Elliott R ... -  《-》

Predicting flood insurance claims with hydrologic and socioeconomic demographics via machine learning: Exploring the roles of topography, minority populations, and political dissimilarity.

Current research on flooding risk often focuses on understanding hazards, de-emphasizing the complex pathways of exposure and vulnerability. We investigated the use of both hydrologic and social demographic data for flood exposure mapping with Random Forest (RF) regression and classification algorithms trained to predict both parcel- and tract-level flood insurance claims within New York State, US. Topographic characteristics best described flood claim frequency, but RF prediction skill was improved at both spatial scales when socioeconomic data was incorporated. Substantial improvements occurred at the tract-level when the percentage of minority residents, housing stock value and age, and the political dissimilarity index of voting precincts were used to predict insurance claims. Census tracts with higher numbers of claims and greater densities of low-lying tax parcels tended to have low proportions of minority residents, newer houses, and less political similarity to state level government. We compared this data-driven approach and a physically-based pluvial flood routing model for prediction of the spatial extents of flooding claims in two nearby catchments of differing land use. The floodplain we defined with physically based modeling agreed well with existing federal flood insurance rate maps, but underestimated the spatial extents of historical claim generating areas. In contrast, RF classification incorporating hydrologic and socioeconomic demographic data likely overestimated the flood-exposed areas. Our research indicates that quantitative incorporation of social data can improve flooding exposure estimates.

Knighton J ，Buchanan B ，Guzman C ，Elliott R ，White E ，Rahm B ... -  《-》

Flooding in semi-unformal urban areas in North Africa: Environmental and psychosocial drivers.

Urban flooding is recognized as a nature-driven disaster shaped by inherent factors such as climate, morphology, and hydrology, affecting vulnerability and flood exposure. While these factors play a paramount role, significant psychosocial intricate drivers are acknowledged, though they are challenging for prediction and assessment. This study delves into these drivers in a specific context, aiming to draw conclusions that extend beyond. It undertakes a comprehensive approach, integrating cloud-based Radar flood detection, analysis of flood causation patterns, and geostatistical analysis of a social survey based on cross-synthesis, contingency analysis, and structural equation modeling. In particular, we characterize the case of the coastal city of Tetouan in Morocco, which is representative in its environmental and socioeconomic settings to most cities in North Africa. It unraveled the nuanced interplay of psychosocial, economic, and territorial dynamics influencing flood exposure. The findings reveal how watershed location molds unique environmental exposures, steering nuanced, emotional, and behavioral responses among residents. Gender and education differentials reveal diverse perceptions and awareness of flood risks. Psychosocial intricacies come to the forefront, portraying education, income, and awareness as crucial mediators influencing cognitive and affective responses. Elevated education, increased income, and heightened awareness correlate with heightened perception and coping strategies. Findings reveal that risk perception significantly and differently influences risk acceptance, coping, and aversion through an array of identified key factors influencing coping strategies, mediating elements in flood damage relationships, and underscoring the pivotal role of perception in shaping responses to risk. Moreover, it found that lower risk acceptance leads to higher coping and aversion, and the latter positively affects coping, indicating that acceptance reduces the motivation to avoid the risk and decreases the willingness to adopt coping strategies to reduce the exposure. The outcomes carry critical implications for comprehending individual and collective social behaviors, informing strategies, and mitigating flood risk that apply at a wider context. It accentuates the inadequacy of relying solely on structural engineering for risk management, citing spatial constraints, misinformation, and lapses in prior-risk memory as compounding exposure challenges. This recognition catalyzes action, advocating tailored awareness campaigns, educational initiatives, and capacity-building programs, spotlighting the need for heightened individual profiles to enhance social understanding, engagement, and resilience. We anticipate profound insights, fostering a richer comprehension of urban flooding complexities and informing adaptive strategies on a broader scale.

Salhi A ，Larifi I ，Salhi H ，Heggy E ... -  《-》

Nonstationary streamflow effects on backwater flood management of the Atchafalaya Basin, USA.

A non-stationary increasing streamflow trend has been observed on the Mississippi River and other major river basins around the world. The current study analyzed the non-stationary streamflow effects (NSFEs) on flood management in backwater areas adjacent to the Atchafalaya Basin floodway in Louisiana, USA. A continuous simulation hydrology model coupled with a quasi-two-dimensional hydrodynamic model of the basin floodway and surrounding regions was used to develop over 180 simulation scenarios by superimposing local flood events (early summer 2014 and late summer 2016) against 90-years' worth of daily Atchafalaya River streamflow hydrographs. The NSFE on the Atchafalaya River induced substantial reductions in the performance of major flood regulating structures with seasonal effects based on the annual flood cycle. Capacity reductions at the structures were demonstrated to trigger a cascade of effects in ostensibly protected backwater areas including amplification of erosion potential near the levee and within tidal passes during early summer floods. Increases in mean and peak flood levels on the order of 15-20 cm during local storm events were shown to extend as far as 20 km away from the floodway protection levee during both early and late summer local flooding scenarios. Low-lying areas closest to the levee were adversely affected during both the high (early summer) and low flow (late summer) periods of the annual discharge cycle. The approach and findings of this study are relevant for risk management in river basins around the world affected by NSFEs.

Miller RL 《-》

Flood hazard delineation in an ungauged catchment by coupling hydrologic and hydraulic models with geospatial techniques-a case study of Koraiyar basin, Tiruchirappalli City, Tamil Nadu, India.

Natarajan S ，Radhakrishnan N 《-》