topidx: Calculates Bevan and Kirkby's topographic wetness index

In ilyamaclean/ecohydrotools: hydrogical modelling for ecological applications with R

Description

topidx is used to calculate the topographic wetness index described in Bevan and Kirkby (1979) basin

Usage

topidx(dem, minslope = atan(0.005/mean(res(dem))))

Arguments

dem	a raster object of elevations.
minslope	an optional positive value specifying the minimum slope allowed (see details).

Details

If slope is zero, infinite topographic wetness index values are returned. Thus, flat areas are assigned a value specifed by minslope. The default value, given by atan(0.005 / mean(res(dem))), assumes that height differences between adjacent cells exceed 0.005. Accumulated flow is multiplied by the cell dimensions, thusdem should have an equal area projection.

Value

a raster object of topographic wetness.

References

Bevan KJ & Kirkby MJ (1979) A physically based, variable contributing area model of basin hydrology. Hydrological Sciences Journal 24: 43-69.

Examples

dem <- aggregate(dtm1m, 20)
plot(log(topidx(dem)), main = "Topographic wetness")

ilyamaclean/ecohydrotools documentation built on June 10, 2019, 5:45 a.m.