Flood risk across Dorset
Dorset's chalk downland means groundwater flooding is a real risk in valleys after long wet winters. The Stour and the Avon meet at Christchurch, where river and tidal flooding combine, and Poole Harbour and Weymouth are exposed to tidal flooding. Parts of the Jurassic Coast are eroding.
Flood zones only show river and sea flooding, and they ignore flood defences. Surface water and reservoir risk aren’t part of the zones – check them on the Environment Agency’s long-term flood risk service, or get the full report, which covers every source.
Rivers that shape local flood risk
Main rivers are managed by the Environment Agency. Smaller watercourses and drainage are the responsibility of Dorset Council and landowners.
River Stour – Blandford, Wimborne and Christchurch
River Frome – Dorchester and Wareham
River Piddle – Wareham
River Avon – Christchurch
River Wey – Weymouth
Poole Harbour and the coast – Poole, Weymouth and Lyme Regis
Who manages flood risk here
Dorset Council and Bournemouth, Christchurch and Poole Council are the Lead Local Flood Authorities, responsible for surface water, groundwater and ordinary watercourses. The Environment Agency manages main rivers and the sea, and issues flood warnings. The same councils also decide planning applications – and asks for a flood risk assessment in Flood Zones 2 and 3.
Getting a written answer for an address
The free check describes the area around your postcode. For a specific property, the full report checks your exact address against every flood dataset and gives you a dated PDF to share with your surveyor, conveyancer or insurer.
For planning decisions, your local council has the final say.
