topdistw: Distributes surface water by topographic wetness

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

Description

topdistw surface water, typically within a basin, by the topograhic wetness index of each basin grid cell

Usage

topdistw(tx, wvol, p = 0.3, xres, yres)

Arguments

tx	a vector or matrix of topographic wetness index values
wvol	a single numeric value of basin water volume (m^3)
p	a single numeric value of to power adjustment to apply to topographic wetness index values (see details)
xres	x grid cell resolution (m)
yres	y grid cell resolution (m)

Details

the coefficient p scales the relationship between topographic wetness and the distribution of surface water. If p = 1, soil moisture is strongly concentrated in cells with a high topographic wetness. If p = 0, soil moisture is evenly distributed across the basin. The correct choice of p depends on sub-grid scale variation in basin depressions, and on complex lateral flows, and thus best determined empirically. A choice of 0.3 for is likely to provide a reasonable approximation.

Value

a vector or matrix of surface water depth (mm) for each grid cell of tx

See Also

topidx()

Examples

library(raster)
tpx <- topidx(dtm100m)
# average depth on 10 mm
sel <- which(is.na(is_raster(tpx) == F))
wvol <- 10 * 100 * 100 * length(sel) / 1000
# NB - not distributed by basin
swd1 <- topdistw(is_raster(tpx), wvol, p = 0.3, xres = 100, yres = 100)
swd2 <- topdistw(is_raster(tpx), wvol, p = 0.1, xres = 100, yres = 100)
plot(if_raster(swd1, dtm100m))
plot(if_raster(swd2, dtm100m))

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