Flooding

Section 1What flooding is

Flooding is the temporary covering of normally dry land by water. It happens when more water arrives than the land or drainage system can handle. Floods are one of the most common and damaging natural hazards worldwide.

Section 2Main types and causes

River flood — heavy or prolonged rainfall fills a river beyond its banks; develops over hours or days. Flash flood — sudden intense rain (especially in mountainous or paved areas) causes rapid rise; can occur with little warning. Coastal flood — storm surge from a hurricane pushes sea water inland. Urban flood — heavy rain overwhelms drains and runs off paved surfaces with nowhere to go. Dam or levee failure — engineered structures break, releasing held water suddenly.

Section 3Effects

Loss of life and injury, especially in fast-onset flash floods. Damage to homes, roads, bridges, and crops. Contamination of drinking water from sewage and run-off. Displacement of communities. Economic losses from damaged infrastructure and lost work. In Jamaica, floods from hurricane rainfall and heavy storms have repeatedly caused major damage in low-lying parishes.

Section 4Prevention and response

Engineering: levees, flood walls, retention ponds, drainage upgrades, dams. Planning: avoid building on floodplains, restore wetlands that absorb water, keep coastal vegetation. Early warning: weather monitoring, public alerts, evacuation plans. During a flood: move to higher ground, avoid flood water (it can be deeper, faster, and dirtier than it looks), follow official guidance.