floodrisk

Flood risk is the potential for adverse consequences caused by flood events in a specified area and period. It is commonly understood as a function of the flood hazard, the exposure of people and assets, and their vulnerability to damage. In quantitative terms, risk is often approximated as risk equals hazard times exposure times vulnerability, though exact formulations vary.

Hazard describes the physical flood process; its probability, magnitude, extent, depth, and duration—typically depicted in flood hazard maps and return-period estimates. Exposure encompasses people, buildings, infrastructure, crops, and services located in flood-prone zones. Vulnerability reflects how susceptible assets are to damage and how quickly communities can recover, influenced by construction, maintenance, and preparedness.

Assessment methods combine hydrological and hydraulic modeling with geographic information systems to produce probabilistic or scenario-based flood risk assessments. Data sources include topography, rainfall-runoff simulations, river gauge records, land use data, and historical flood losses. Results support land-use planning, infrastructure design, flood defenses, insurance, and emergency preparedness.

Climate change and rapid urbanization are expected to alter flood risk by increasing hazard in some regions and expanding exposure elsewhere. Limitations include data gaps, model uncertainties, and the difficulty of capturing social vulnerability. Effective flood risk management combines non-structural measures—early warning, zoning, and preparedness—with appropriate structural defenses and governance.