What are the increasing risks from river flooding and the threats to people and the environment?

River flooding is becoming more frequent and severe due to both natural and human-induced changes. Two key reasons for the increased risk are the more frequent storms associated with climate change and changes in land use. These factors interact with river systems and drainage basins to create higher flood risks, particularly in areas that are vulnerable.

Why Are River Floods Becoming More Common?

Increased Frequency and Intensity of Storms

• Climate change is increasing global temperatures, resulting in increased evaporation and more intense rainfall.
• The UK has experienced more frequent extreme weather events, such as Storm Ciara and Storm Dennis in 2020.
• Intense rainfall in short periods overwhelms drainage systems, causing rivers to rise rapidly.
• Repeated storms close together saturate the soil, resulting in increased surface runoff and a higher flood risk.

Land Use Changes

Human activity has altered natural landscapes, reducing their ability to absorb rainfall and increasing flood hazards:

• Urbanisation: Towns and cities are expanding onto floodplains. Concrete and tarmac are impermeable surfaces that increase runoff into rivers.
• Deforestation: Trees intercept rainwater and encourage infiltration. Removing trees means water reaches rivers more quickly.
• Farming Practices: Ploughing and compacting soil reduce infiltration and increase overland flow, particularly when fields are left bare.
• Drains and Sewers: Designed to remove water quickly, these systems can direct rainfall directly into rivers during storms, thereby speeding up the river’s response.

Threats to People

Flooding can have serious social and economic consequences for individuals and communities:

• Damage to Homes and Property: Floodwater can ruin furniture, electrical systems, and personal belongings.
• Evacuation and Homelessness: Flooding may force people to leave their homes, sometimes for weeks or months.
• Disruption to Services: Roads, railways, schools, and hospitals may close, reducing access to emergency services.
• Health Risks: Standing water can lead to contamination, spreading diseases like cholera or causing mental health strain.
• Insurance Costs: Rebuilding and recovery are expensive. Many people in flood-prone areas face rising premiums, or can’t get insurance at all.

Threats to the Environment

Floods not only affect people, but they also impact the natural landscape:

• Soil Erosion: Fast-flowing floodwaters can wash away topsoil and damage farmland.
• Habitat Destruction: Riverside habitats, wetlands, and animal homes can be damaged or destroyed.
• Water Pollution: Floods can wash chemicals, oil, and sewage into rivers, harming aquatic life and affecting drinking water.
• Sedimentation: When rivers flood, they can deposit large amounts of sediment, which can smother habitats and reduce water quality.

A Growing Challenge

Increased river flooding is a complex issue driven by global and local changes. As climate change accelerates and human land use expands, the threat to both people and the environment is growing. Managing these risks requires a combination of flood defences, sustainable land-use planning, and improved forecasting.