River Flooding Explained

River flooding happens when a river, brook, stream or watercourse rises and spills onto nearby land. It can develop after prolonged rainfall, intense storms, snowmelt or when catchments are already saturated.

What causes river flooding?

• Heavy or prolonged rainfall across a river catchment.
• Saturated ground that cannot absorb more water.
• Blocked channels, culverts or restrictions that slow water flow.
• High tributary flows combining downstream.
• Tidal influence in some river areas close to the coast.

Why river levels can rise quickly

Some rivers respond quickly to heavy rainfall, especially in steep catchments or urban areas where water runs off hard surfaces. Larger rivers may respond more slowly but can stay high for longer.

How to prepare if you live near a river

• Check whether your address is in an area at long-term flood risk.
• Sign up for flood warnings where available.
• Prepare a personal flood plan.
• Move valuables and key documents away from ground-floor areas if warnings are issued.
• Know safe routes away from riverside roads, bridges and low points.

During river flooding

• Do not walk beside fast-flowing rivers or flooded banks.
• Avoid driving through flood water.
• Follow emergency services and local authority instructions.
• Keep children and pets away from flood water and river edges.

Useful checks

The official flood checking service lets users check current flood warnings and alerts, river, sea, groundwater and rainfall levels, plus flood risk over the next five days. GOV.UK also provides a long-term flood risk service covering rivers and the sea, surface water, reservoirs and groundwater where available.