The Severn Estuary is the estuary of the River Severn, flowing into the Bristol Channel between South West England and South Wales. Its very high tidal range, approximately 50 feet (15 m), creates valuable intertidal habitats and has led to the area being at the centre of discussions in the UK regarding renewable tidal energy.
The Severn estuary at Beachley, Gloucestershire, showing the strong tidal currents.
Diagram of a plan to harness tidal power on the River Severn circa 1921. Caption from Popular Mechanics Magazine 1921
View of Severn Estuary from Newport Wetlands
An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environments and are an example of an ecotone. Estuaries are subject both to marine influences such as tides, waves, and the influx of saline water, and to fluvial influences such as flows of freshwater and sediment. The mixing of seawater and freshwater provides high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world.
Río de la Plata estuary
New York–New Jersey Harbor Estuary
River Exe estuary
Estuary mouth located in Darwin, Northern Territory, Australia