Coastal flooding
Coastal flooding is the inundation of normally dry land along a coast by seawater, caused by elevated water levels, waves, or both.
Storm surge: A temporary rise in sea level caused mainly by storm winds pushing water toward the coast. Strong onshore winds can raise coastal water enough to flood land beyond the normal tide.
Coastal flood forecasting: The prediction of coastal water levels, inundation, or flood impacts using observations and models. Forecasts combine tides, surge, waves, and sea-level conditions to anticipate inundation.
1938 New England hurricane: A powerful 1938 Atlantic hurricane that struck the northeastern United States and produced destructive coastal flooding. Its storm surge and waves devastated shoreline communities across New England.
Riverine flooding: The inundation of land when rivers overflow their banks or exceed channel capacity. It originates from overflowing rivers, although high coastal water can impede river drainage.
Tide: The periodic rise and fall of sea level, driven chiefly by the Moon’s and Sun’s gravity. High tides raise the baseline on which storm-driven water levels build.
Flood hazard map: A map showing areas exposed to flooding under specified scenarios or probabilities. Hazard maps identify locations where coastal water can reach under modeled conditions.
Hurricane Katrina: A 2005 Atlantic hurricane whose storm surge and levee failures caused catastrophic flooding in the Gulf Coast region. Coastal surge combined with failed flood defenses to inundate parts of the New Orleans region.
Flash flood: A rapid flood that develops within minutes or hours, often after intense rainfall or sudden water release. Its trigger is rapid runoff or water release rather than elevated seawater.
Wave run-up: The vertical distance waves travel up a beach, slope, or coastal structure above still water level. Wave run-up can carry seawater over a shoreline even without exceptional still-water levels.
Flood risk: The potential consequences of flooding, shaped by hazard, exposure, and vulnerability. Inundation becomes a risk when people, infrastructure, or valued ecosystems are exposed.