This brief report focusses on work carried out on behalf of the Environment Agency (South-Western Region), formerly the National Rivers Authority.
The Environment Agency is responsible for the monitoring and public safeguarding of rivers and their catchments in England and Wales. The South Western Region is currently developing a Geographic Information System to enable the catchments in this region to be monitored more effectively. A vital part of the information to be contained within the GIS is data on conservation areas. In total 5195 sites needed to be captured from paper maps held by authorities such as County and District Councils, Wildlife Trusts, English Heritage and the Royal Society for the Protection of Birds. These sites ranged from large polygons such as National Park boundaries and Areas of Outstanding Natural Beauty to small areas designated as Local or County Wildlife Sites.
The preferred method of data capture involved 'heads-up' digitising using PCI's ImageWorks software (part of the EASI/PACE image processing system). Black and white raster 1:10000 scale map files (TIFF format ) supplied by the Ordnance Survey covering a 5 x 5 km area were assigned geographic coordinates for the top left and bottom right corners of each tile. Each Conservation Designation (e.g. Site of Special Scientific Interest) was digitised over the raster backdrop using the paper maps as a reference. Errors on the original paper maps, which occurred typically at the edges of map sheets, were identified and rectified during the quality checking and topological integrity checking phases of the project. The Conservation Designation vectors were exported to an Environment Agency internal ASCII format for input to the GIS system.
The figure below show an example of the Conservation
Designation boundaries captured for a section of the Avon valley
in west Hampshire. Boundaries include the Avon Valley Site of
Special Scientific Interest.
Download a larger image
The vector data could be superimposed upon satellite image
data. The image below shows an enhanced band 2,3,1 pseudo
true-colour composite image acquired by the SPOT satellite in
July 1994. This image was processed by I.S. Ltd on behalf of the
Wessex region of the then National Rivers Authority in order to
identify areas of maize. The NRA wished to identify the
concentrations of maize fields and relate these to water
boreholes which were found to be contminated with the pesticide
Atrazene. The maize fields have been highlighted in yellow.
Download a larger image
Remote Sensing and GIS Mapping Software
Satellite Image Catalogue
Mapping Peat Bogs in Lewis, Scotland
Fuelwood Assessment and Management in Chad
Conservation Areas Captured in SW England