Canvey Island risks to London and the Thames estuary area. It is proposed that the western side of Canvey is developed as a site which is either temporarily flooded at times of risk, or transformed into a permanent wetland. Developments in the 20th century have produced a marked contrast between the environments in the east and west of the island. The eastern half of the island is allocated to residential areas, the main public amenities and a small holiday camp and seafront, while the western half of the island is mainly farmland, marshes and industrial areas. The marshes in the west include
Yalu River its length. Most of the river freezes during winter and can be crossed on foot. The depth of the Yalu River varies from some of the more shallow parts on the eastern side in Hyesan (1 m) to the deeper parts of the river near the Yellow Sea (2.5 m). The estuary is the site of the Amrok River estuary Important Bird Area, identified as such by BirdLife International. About 205 islands are on the Yalu. A 1962 border treaty between North Korea and China split the islands according to which ethnic group was living on each island. North Korea