The Hydrography and Hydrographic Balances of the North Sea

Abstract

The North Sea is a shallow (30--200 m), rectangular-shaped basin with a shelving topography from south to north and a deep (up to 600 m) trough, the Norwegian Rinne, on its eastern margin. It encompasses a surface area of 575,000 km2 with a volume of 40.3 km3 (ICES 1983). The region is subject to oceanic influences in the north and to a minor extent via the Dover Straits; it is strongly influenced on the remaining three sides by terrestrial inputs, including a contribution from the Baltic through the Skagerrak. A knowledge of hydrography and water balances is needed to assess the impact of pollutant inputs from the major industrial nations which surround this partially enclosed sea. The physical oceanography of the North Sea has been reviewed by Hill (1973), Lee (1980) and Otto (1983); the present chapter seeks to summarise and update these descriptions, drawing attention to features of importance to pollution.