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: SpatRaster object with the digital elevation model of the region
river: An object of class sf::sf or sf::sfc representing the river

Value

River valley as a simple feature geometry of class sfc_MULTIPOLYGON

Examples

if (FALSE) { # interactive()
bucharest_osm <- get_osm_example_data()
bucharest_dem <- get_dem_example_data()
delineate_valley(bucharest_dem, bucharest_osm$river_centerline)
}