Flooding and Coastal Risk in Havant

Tidal flooding, surface water and climate adaptation

Havant's location at the head of Langstone Harbour, on low-lying coastal plain, means that flooding is a real and recurring risk for parts of the town and surrounding area. The combination of tidal surges, high rainfall and rising sea levels makes flood management one of the most important long-term challenges facing the borough.

Tidal flooding is the primary risk. When high spring tides coincide with storm surges and onshore winds, sea water can overtop or breach the harbour defences, flooding low-lying areas near the harbour shore. Langstone and the southern fringes of Havant are the most vulnerable to tidal flooding. The A259 coast road has been flooded on several occasions, and properties close to the harbour edge face a real risk of inundation during extreme tidal events.

Surface water flooding occurs when heavy rainfall overwhelms the drainage system, causing water to pool on roads and in low-lying areas. The flat terrain of the coastal plain means that water drains slowly, and the combination of impermeable surfaces in the built-up area and the limited capacity of older drainage infrastructure can lead to localised flooding during intense rainfall events.

The Environment Agency manages flood risk at a strategic level, maintaining flood defences, producing flood risk maps and issuing flood warnings. The agency's online flood risk map shows the areas of Havant that are at risk of flooding from rivers and the sea, and from surface water. Residents can sign up for flood warnings, which provide advance notice when flooding is expected.

Havant Borough Council works with the Environment Agency and Hampshire County Council on flood risk management. The council's planning policies seek to avoid new development in the highest-risk areas and require flood risk assessments for developments in areas of potential risk. Sustainable drainage systems are required on new developments to manage surface water runoff.

Sea level rise is the long-term concern. Climate projections indicate that sea levels around the south coast will continue to rise during the coming decades, increasing the frequency and severity of tidal flooding. Adaptation strategies, including upgraded flood defences, managed retreat in some areas, and property-level resilience measures, will be needed to manage this growing risk.

For individual residents, understanding flood risk is important when buying property, insuring a home and preparing for extreme weather events. The government's flood risk website provides property-level information, and insurance availability is governed by the Flood Re scheme for residential properties at high risk.

Sea level rise is the long-term concern. Climate projections indicate that sea levels around the south coast will continue to rise during the coming decades, increasing the frequency and severity of tidal flooding. Adaptation strategies, including upgraded flood defences, managed retreat in some areas, and property-level resilience measures, will be needed to manage this growing risk. For individual residents, understanding flood risk is important when buying property, insuring a home and preparing for extreme weather events. The government's flood risk website provides property-level information, and insurance availability is governed by the Flood Re scheme for residential properties at high risk.