16 February 2015 | rusty1052
Through MapLesotho every water body in the country is being mapped, with approximately 80% complete to date. Even in this incomplete state we are able to download the data and import into a PostGIS enabled database. The Lesotho data is downloaded from geofrabik (download.geofabrik.de/africa/lesotho.html) who provide daily snapshots of all the data.
By taking one of the well mapped features streams and rivers, and analysing this in tandem with buildings has allowed us to see the proximity of buildings to waterbodies.
As further localised extract was taken from Leribe in order to assertion the number of buildings and their respective which are potentially at risk from flooding due to proximity watercourses.
It was found that of the buildings mapped in Leribe approximately 38% were at risk of flooding. When adding features to OSM we use satellite imagery which can be up to 2 years old. When further examining the building type, of those tagged as under construction it was found that over 50% of those were at risk of flooding.