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    Environment Agency

    Environment Agency
    Historic Flood Maps

    • Specialist data conversion from non-standard mapping sources
    • Quick and easy accessibility to historic flood information related to current day map features
    • Full integration with GIS search, navigation and analytical tools to maximise the data’s value 
    Environment Agency


    Historic reconnaissance maps can provide very useful flood event information and are a valuable resource. However, the original paper map and photo compilations can be difficult to access, are in deteriorating condition, and some of the information they contain was not in GIS format and needed to be included in the Environment Agency's published flood map.

    Landmark has provided expert data conversion assistance to the Environment Agency to capture historic records of flood events for use within the Agency’s geographic information systems and the Environment Agency’s published flood map.

    The Environment Agency has built a customized GIS toolbar to search and display the historic flood event data, in relation to current day digital mapping. The purpose is to allow easier comparisons between flood events of different dates, to enable other EA staff to view the historic maps in a GIS environment and also to include, where possible, this digitised data in the EA Published Flood map.


    Environment Agency

    Our Solution

    Landmark was asked to undertake the conversion because of their specialist knowledge of converting historic map data from complex and variable sources into seamless digital geodatabases.

    The contract involved the following elements:

    • Initial advice on the most appropriate geospatial data model for storing the data
    • On site scanning of original maps to identify all map elements within the images and without damaging the original documents or removing them from site
    • Specialist geo-referencing of maps that had been compiled and glued together from various sources, scales and vintage, did not often have any form of grid identification and were commonly aligned along to suit the flood extents rather than to north
    • The generation of business rules to guide the capture process and to assign a confidence level to the captured data
    • Capture/interpretation of individual flood extents and associated attributes in relation to current day Master Map data
    • Quality Assurance and validation of boundaries
    • Attribution of digistised data that permitted ‘hot linking’ from digitised data to source map
    • The combination of individual flood extents from different periods into a seamless geodatabase with links back to the original geo-referenced scanned map images

    Benefits Realised

    Operational benefits identified by the Environment Agency include:

    • Speed and ease of access to information
    • Information related to current day map features
    • Ability to view multiple flood events together
    • Integration with GIS search, navigation and analytical tools to maximise the value of the data