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11/01/2010

The coastal map
Now on Géoportail you can view the coastal map, which is the product of assembling IGN’s land maps with the maps of the seas and oceans produced by the SHOM (Hydrographic and Oceanographic Service of the French Navy). Another great reference tool to improve your knowledge and understanding of France’s coastal areas
Either side of the coastline
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To make this coastal map, maps of the areas to 10km either side of the coastline (demarcation line between marine and terrestrial zones, as determined by the two organisations concerned) produced by IGN and the SHOM (Hydrographic and Oceanographic Service of the French Navy) were put together edge to edge. |
How can I display the coastal map ?
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- Go to the commune of your choice that is situated near the coast - In the ‘Layers catalogue’, open the ‘COASTLINE’ file, and tick the ‘Coastal map’ box |
Help with reading the map
The marine map is designed to meet the requirements of marine navigation. It shows, amongst others, the sea’s depth, the nature of the sea-bed, maritime signals etc. *
Below you will find some tips to improve your understanding of the marine part of the coastal map.
> Ocean depth
Depth is indicated by the following colours:
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green : indicates the shore (whole of the zone covered at highest tides and uncovered at lowest) |
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dark blue: indicates shallow zones |
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light blue: indicates deeper zones |
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white: indicates deepest zones |
The sounding, that is, the height of the water as compared with the level at the lowest tide, (hydrographic zero) is indicated by two figures (usually in italics): the first number represents the metres and the second, in subscript, represents the decimetres. If the first number is underlined, the level is a negative level as it only emerges at the lowest tides (above the map zero).
If the figures are not in italics the sounding is less reliable.
> Buoys
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The buoys represent fixed or floating maritime buoyage (beacons, boat hooks, buoys etc.) |
> Other symbols
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You can find an exhaustive list of all the symbols used on the marine section of the coastal map in the marine mapping document on the SHOM website. |
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Why do we need a coastal map ?
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The ‘coastal map’ layer currently covers the North Sea, Channel and Atlantic coasts, with the Mediterranean coast due to be added by the end of 2009.
* NB : the coastal map cannot be used instead of a navigation map for sailing purposes, as it has no legal value.


