New Formula Links Urban Design and Flood Severity

As cities worldwide face increased flooding due to stronger storms and urban expansion, new research from UC Irvine reveals that the layout of a neighborhood—specifically its building density and street network—plays a significant role in flood severity. Published in *Nature Communications*, the study introduces a statistical mechanics-based formula that simplifies the assessment of flood risks tied to land development.

Inspired by physics, the research team, led by UC Irvine’s Department of Civil and Environmental Engineering, adapted methods used to analyze complex systems like porous solids to develop a universal model for predicting flood hazards in different cities. This model highlights the connection between urban design, rainfall intensity, and flood losses.

Ph.D. candidate Sarah Balaian emphasized that future severe weather events will disproportionately impact dense urban populations, especially those lacking resources for protection or evacuation. Current global flood modeling is limited by inadequate data, prompting the team to create a new approach based on the physical layout of urban areas.

Brett Sanders, co-author and professor at UC Irvine, explained that the formula was derived from thousands of flood simulations across diverse city layouts. Grounded in physical laws, the equation offers a practical tool for global planning and vulnerability assessments and will be integrated into civil engineering education to prepare future engineers to manage flood risks associated with urban development.