Spithead is situated on the western side of the Portsmouth Channel, and lies in a deep and sheltered section of the Solent.
Portsmouth is a large city on the south coast, and provides a strategically important site for the Royal Navy, and has historically been a major naval base. The natural variability of the shoreline is limited.
The shoreline comprises a shingle beach on the foreshore and several large banks to the offshore side. The bathymetry is complex within the harbour mouth with numerous sand bars and shoals, such as Spit Sand. Spithead is controlled by shoreline processes as well as the behaviour of the harbour's entrance.
The presence of HM Portsmouth naval base means the shoreline is heavily fortified. The shoreline has become increasingly developed over time, as the naval port has increased in importance. The shoreline structures limit the erosion of the coast, but limit the amount of sediment being transported from the beach to the offshore zone. Shoreline structures limit sediment availability. Dredging also exacerbates the problem.
The area of seabed adjacent to Spithead is shallow compared to the deep water channels of the Solent, between Spithead and Ryde Sands.
The chart illustrates that the main channel of Portsmouth Harbour has been dredged to 6 fathoms. Along the banks of the channel, the depth varies substantially. The edges of the bank consist of muds which are exposed at low tide.
Spit Head is situated on the western side of the Portsmouth Channel, and lies in a deep and sheltered section of the Solent.
It comprises a shingle beach on the foreshore and several large banks to the offshore side. The bathymetry is complex within the harbour mouth with numerous sand bars and shoals, such as Spit Sand.
The presence of HM Portsmouth naval base means the shoreline is heavily fortified.
1897 source map
The chart illustrates that the bathymetry is again extremely detailed. The shoreline has become substantially more developed than previous charts. Gosport and Portsmouth are built up with a substantial amount of naval buildings on Gosport's shores. The chart illustrates the varying depths of the area, with the deepest water being in the main harbour entrance.
Adjacent to the harbour entrance, the large sand shoal provides shelter and shallower water. The main channel has also been dredged to 29 feet. This is significantly deeper than the adjacent areas of 1-2 feet.
1914 source map
There is very little difference to 1914, in an area comprising a deep channel and shoals at the harbour mouth. The harbour entrance is surrounded by several naval buildings and shoreline structures defending the coastline.
The chart highlights the amount of anthropogenic development along the shoreline, particularly the influence of the navy. The man-made structures and the dredging programme which has occurred have changed the structure of the harbour mouth, particularly the main channel.
Little change has occurred in the plan form of the harbour mouth and the general morphological shape of the sand bars forming at the entrance. However, depth of the seabed below the surface has changed slightly.
It is clear from the chart, how the influence of the Royal Navy along this shoreline has determined the driving forces behind the coastal change.
1924 source map
The chart illustrates a deep channel in Portsmouth Harbour, surrounded by sand bars and intertidal mud flats, which are exposed on the ebb tide. The shoreline is heavily defended with sea walls and quaysides.
The main shipping channel has been dredged to allow for the larger ships and ferries entering the harbour. The area is still influenced by the Navy who occupy a substantial amount of Gosport and the eastern side of the harbour channel (Portsmouth).
2001 source map
You can also compare all the Spithead maps on a single page.
This feature has been made possible by a partnership between The Crown Estate and The Open University. The Crown Estate manages property in the UK within the Marine, Urban and Rural Estates and all their revenue surplus is returned to the Treasury. The Marine Stewardship Fund, which supports this project, contributes to the good management and stewardship of the marine estate. The Open University is committed to making education available to all.
With thanks to the National Maritime Museum. Find out more about the National Maritime Museum's collections.
We would like to thank Sefton Coastal Partnership for access to and use of some of its resources .
We would also like to thank the Hydrographic Office for permission to use their charts and to ABP Humber for additional permission to use the 2001 Humber chart.