get_distance {rdwplus}

Compute Euclidean distance to a survey site or stream line within a watershed

Description

This function is needed to compute Euclidean distance from a feature of interest in a watershed raster.

Usage

get_distance(target, out, overwrite = FALSE)

Arguments

target

File name of the watershed outlet or streams (as a raster) in the current GRASS mapset.

out

File path for the result to be written.

overwrite

A logical indicating whether the outputs of this function should be allowed to overwrite existing files.

Value

Nothing. A file with the name basename(out) will be created in the current GRASS mapset.

Examples

if(check_running()){

# Retrieve paths to data sets
dem <- system.file("extdata", "dem.tif", package = "rdwplus")
lus <- system.file("extdata", "landuse.tif", package = "rdwplus")
sts <- system.file("extdata", "site.shp", package = "rdwplus")
stm <- system.file("extdata", "streams.shp", package = "rdwplus")

# Set environment
set_envir(dem)

# Get other data sets (stream layer, sites, land use, etc.)
raster_to_mapset(lus)
vector_to_mapset(c(stm, sts))

# Reclassify streams
out_stream <- paste0(tempdir(), "/streams.tif")
rasterise_stream("streams", out_stream, TRUE)
reclassify_streams("streams.tif", "streams01.tif", overwrite = TRUE)

# Burn in the streams to the DEM
burn_in("dem.tif", "streams01.tif", "burndem.tif", overwrite = TRUE)

# Fill dem
fill_sinks("burndem.tif", "filldem.tif", "fd1.tif", "sinks.tif", overwrite = TRUE)

# Derive flow direction and accumulation grids
derive_flow("dem.tif", "fd.tif", "fa.tif", overwrite = T)

# Derive a new stream raster from the FA grid
derive_streams("dem.tif", "fa.tif", "new_stm.tif", "new_stm", min_acc = 200, overwrite = T)

# Get distances
get_distance("new_stm.tif", "dist_from_stream.tif", T)

}