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Identifying the Impact of Human Made Transformations of Historical Watercourses and Flood Risk

In the past, many urban rivers were piped and buried either to simplify development, hide pollution or in an attempt to reduce flood risk and these factors define a culverted watercourse. A large amount of these watercourses are not mapped, and if they are, then their original nature is not clearly identifiable due to being recorded as part of the sewer network. Where these culverted watercourses are not mapped due to being lost to time and development, we expressed these to be so-called ‘lost rivers’. There is a lack of awareness of the flood risk in catchments housing these rivers, and because many of them are incorrectly mapped as sewers, there is often confusion over their legal status and responsibility for their maintenance. To identify the culverted watercourses many datasets were used including LiDAR data (Ground Elevation Data), historical maps (earliest 1840's), asset data (Sewer network), and the river network. Automatic and manual identification of potential culverted watercourses were carried out and then the mapped assets are analysed with flooding data to understand the impacts. A GIS map has been created showing all potential lost rivers and sites of culverted watercourses in the North London area.