Extract the river valley from the DEM — delineate

The slope of the digital elevation model (DEM) is used as friction (cost) surface to compute the cost distance from any grid cell of the raster to the river. A characteristic value (default: the mean) of the cost distance distribution in a region surrounding the river (default: a buffer region of 2 km) is then calculated, and used to threshold the cost-distance surface. The resulting area is then "polygonized" to obtain the valley boundary as a simple feature geometry.

Usage

delineate_valley(dem, river)

Arguments

dem: Digital elevation model of the region
river: A simple feature geometry representing the river

Value

River valley as a simple feature geometry

Examples

if (!requireNamespace("CRiSpData", quietly = TRUE)) {
  message("Install CRiSpData from GitHub to run this example.")
} else {
  delineate_valley(terra::unwrap(CRiSpData::bucharest_dem),
                   CRiSpData::bucharest_osm$river_centerline)
}
#> Geometry set for 1 feature 
#> Geometry type: MULTIPOLYGON
#> Dimension:     XY
#> Bounding box:  xmin: 412402.4 ymin: 4910692 xmax: 448052.6 ymax: 4928318
#> Projected CRS: WGS 84 / UTM zone 35N
#> MULTIPOLYGON (((445998.1 4912232, 445998.1 4912...