An estuary is a semi-enclosed coastal body of water with an open connection to the sea. Here fresh water from land drainage meets and mixes with saline water from the sea. Estuaries are highly dynamic, with a multitude of processes playing a role in their formation and maintenance (tides, waves, freshwater discharge, the influx of saline water and sediment, biophysical interactions). These processes may influence and interact with each other, making estuaries complex environments to understand and to work in. Estuaries belong to the most productive natural habitats in the world. Being home to unique plant and animal communities, they provide for multiple ecosystem services. Estuaries are not only valuable ecosystems to humans, but also to an abundant wildlife.
Different types of estuaries are found around the world (coastal plains, fjords, lagoons, etc.). These can be classified based on their geomorphology and water circulation patterns.
For more background information about estuaries, see Estuarine environment
Read more about estuarine solutions specifically in the UK in the Environmental Agency's evidence-base directory.