Thames Estuary Airport a major International hub at Cliffe which would link in with the HS1 line through Kent to St Pancras. The Cameron government was committed to a full Aviation Review and a scoping study was released in March 2011. The "Marinair" proposal was put forward in the 1990s, in which an airport would be built on an offshore artificial island in the Thames estuary, north east of the Isle of Sheppey. When the proposal was put forward again in the government's 2002 consultation, it was rejected on the grounds of insufficient information and prohibitive expense. The Marinair plans had been developed
Estuary river valleys are also known as coastal plain estuaries. In places where the sea level is rising relative to the land, sea water progressively penetrates into river valleys and the topography of the estuary remains similar to that of a river valley. This is the most common type of estuary in temperate climates. Well-studied estuaries include the Severn Estuary in the United Kingdom and the Ems Dollard along the Dutch-German border. The width-to-depth ratio of these estuaries is typically large, appearing wedge-shaped (in cross-section) in the inner part and broadening and deepening seaward. Water depths rarely exceed . Examples of