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Create stream network

Source: R/streams.r
streams.Rd

This function estimates the course of streams and rivers from an elevation raster. It is based on the GRASS module \href{https://grass.osgeo.org/grass84/manuals/r.stream.extract.html}{r.stream.extract}, where more details can be found.

Usage

# S4 method for class 'GRaster'
streams(
  x,
  accumulation = NULL,
  depression = NULL,
  flowThreshold = 1,
  dirThreshold = 1,
  montgomery = 0,
  minLength = 1
)

Arguments

x

A GRaster representing elevation.

accumulation

Either NULL (default) or a raster representing flow accumulation. If not supplied, an accumulation will created internally. You can generate an accumulation raster using flow().

depression

Either NULL (default) or a GRaster representing depressions (areas from which streams will not flow out of).

flowThreshold

Numeric > 0: Minimum threshold for a stream to be generated. The default is 1, which is not necessarily a reasonable value.

dirThreshold

Numeric (default is Inf): When flow exceeds this threshold, its direction is estimated using a single-flow direction algorithm. Below this threshold, a multi-direction flow model is used. This is the d8cut parameter in r.stream.extract, and it is only used if accumulation is NULL. The default is 1, which is not necessarily a reasonable value.

montgomery

Numeric: The "Montgomery" exponent for slope, multiplied by accumulation as per accumulation * slope^montgomery. This value is then compared to the threshold to determine if it is sufficient. The default is 0 (i.e., no slope scaling).

minLength

Numeric: First-order streams less than this length are removed (units in cells). Default is 0 (no removal).

Value

A GRaster.

See also

flow(), flowPath(), the \href{https://grass.osgeo.org/grass84/manuals/r.stream.extract.html}{r.stream.extract} module in GRASS

Examples

if (grassStarted()) {

# Setup
library(terra)

# Example data
madElev <- fastData("madElev")

# Convert a SpatRaster to a GRaster
elev <- fast(madElev)

# Calculate stream channels
streams <- streams(elev)
plot(streams)

}