Relative Elevation Model (REM)
Plugin ID: 5475
Generates a Relative Elevation Model (REM): a raster showing how high each cell sits above the nearest river channel, revealing floodplain features such as levees, palaeochannels and terraces. Includes a semi-automatic river line extractor.
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This plugin adds two Processing tools under "REM Tools":
1. Create River Line from DEM (semi-automatic): extracts a river/channel network from a DEM using fill sinks, flow accumulation, thresholding and thinning. The result is meant to be inspected and cleaned by hand before use. For very flat areas (e.g. the Sudd) a hand-drawn line is recommended instead.
2. Generate Relative Elevation Model (REM): samples DEM elevation along the river line, interpolates a smooth river surface (IDW), and subtracts it from the DEM to produce the REM.
IMPORTANT: the DEM and the river line MUST share the same projected (metre-based) coordinate reference system. Geographic (degree-based) data will not work correctly.
The output REM is loaded with a bundled 0-10 m colour ramp suited to floodplain mapping.
