Why is the risk of river flooding increasing in the UK?

The UK is facing an increased risk of river flooding, and this is predicted to get worse in the future.

Climate change

Climate change is influencing the likelihood of river flooding in the UK in several ways:

1. Increased Frequency and Intensity of Depressions: Climate change is leading to more frequent and intense weather depressions, areas of low atmospheric pressure resulting in stormier conditions. These depressions often bring heavy rainfall, which can significantly increase river levels and lead to flooding. The heightened intensity of these weather events means that the volume of water can overwhelm river systems, causing them to overflow their banks more frequently and with greater severity.
2. Increasing Periods of Hot, Dry Weather: Extended periods of hot, dry weather, which are becoming more common due to climate change, can impact river flooding in a somewhat paradoxical way. Initially, these conditions lead to drier soil, which reduces the land’s ability to absorb water. When heavy rainfall does occur, this can result in rapid surface runoff into rivers, as the parched ground is less capable of soaking up the water. This sudden influx of water can lead to swift and severe river flooding, especially in areas where the ground is heavily compacted or urbanised.
3. Increasing Periods of Cold Weather: Climate change is also associated with more frequent and severe cold weather events in some regions due to disruptions in weather patterns like the polar vortex. These cold periods can lead to significant snowfall, and when a sudden warm spell follows, the rapid melting of this snow contributes to increased river levels and potential flooding. This is especially concerning when river systems are not adapted to handle large volumes of meltwater, leading to an elevated risk of floods.

Land-use change

Land-use changes are significantly contributing to the increased risk of river flooding in the UK in several ways:

1. Urbanisation: The expansion of urban areas replaces natural, absorbent ground with impermeable surfaces like concrete and asphalt. This increases surface runoff during heavy rainfall, as water cannot percolate into the ground, raising the risk of river flooding.
2. Deforestation: Removing trees and vegetation for agriculture or urban development reduces the land’s ability to absorb rainwater. Trees and plants play a critical role in absorbing water and reducing surface runoff, so their removal increases water flow directly into rivers.
3. Drainage Systems and Land Reclamation: The construction of drainage systems to convert wetlands and other natural landscapes into agricultural or urban land can alter natural water courses. This often leads to quicker runoff into rivers and reduces the landscape’s capacity to store excess water, increasing flood risk.
4. Agricultural Practices: Certain agricultural practices, such as overgrazing and removing hedgerows, can reduce the soil’s ability to absorb water and increase soil erosion. This leads to higher runoff into rivers and contributes to the silting up of riverbeds, which can decrease their capacity to carry water and lead to flooding.
5. Floodplain Development: Building on floodplains reduces the area available for rivers to expand naturally during high flows. This encroachment into floodplains can exacerbate flooding, as the river has less space to spread out, and the water level rises more quickly.

What are the threats of flooding to people and the environment?

Threats to people:

• Loss of Life and Injury: Floods pose a significant risk to human safety, potentially leading to fatalities and physical injuries.
• Home and Property Damage: Flooding can cause severe damage to houses and personal property, resulting in substantial repair costs and loss of valuables.
• Health Risks: There’s an increased risk of waterborne diseases, mental health issues due to trauma and displacement, and physical injuries during cleanup.
• Displacement and Relocation: People may be forced to evacuate their homes, leading to temporary or permanent displacement.
• Economic Hardship: Floods can result in job loss, business disruption, and increased insurance premiums, causing financial strain.
• Disruption to Education: Flooding can lead to school closures, impacting children’s education and daily routine.
• Transportation Disruptions: Floods can damage transport infrastructure, leading to travel delays and isolation of communities.
• Access to Services: Flooding can disrupt essential services such as healthcare, emergency services, and utilities, affecting daily life and well-being.

Threats to the environment:

• Habitat Destruction: Flooding can destroy wildlife habitats, leading to biodiversity loss and ecosystem disruption.
• Soil Erosion: Intense water flow can erode riverbanks and nearby land, degrading soil quality and affecting land stability.
• Water Pollution: Floodwaters often carry pollutants, chemicals, and sewage, contaminating rivers and surrounding environments.
• Loss of Plant Life: Excessive water can damage or destroy plant life, impacting local flora and fauna dependent on these plants.
• Disruption of Aquatic Life: Sudden changes in water levels and quality can harm fish and other aquatic species, disrupting the ecological balance.
• Increased Greenhouse Gas Emissions: Flooding can release greenhouse gases from submerged soils and vegetation.
• Spread of Invasive Species: Floodwaters can transport invasive plant and animal species to new areas, threatening native biodiversity.