flowtimes: Calculates flow time to basin bottom

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

Description

flowtimes calculates flow paths and applies the flow velocity function to calculate the the time taken for water from each cell to reach the lowest point in the basin. It is used to calculate which cells contribute to peak flow.

Usage

flowtimes(dem, nr = 0.025, wf = 5e-04, maxiter = 100,
  minslope = atan(0.005/mean(res(dem))))

Arguments

dem	a raster object of elevations
nr	an optional single numeric value, or a raster object, two-dimensional array or matrix of Manning's roughness coefficients (see details)
wf	n optional single numeric value, or a raster object, two-dimensional array or matrix of mean water volumes (see details)
maxiter	a positive integer specifying the maximum number of iterations allowed when flow path algorithm gets stuck in a loop.
minslope	an optional positive value specifying the minimum slope allowed (see details).

Details

If wf is a single value it should approximate the mean proportion of land wetted. If wf is an array, matrix or raster object, then values should approximate the mean proportion of land wetted seperately for each basin, but should not be variable within basins. 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. Values of nr fora variaty of substrate types can be found here: http://www.fsl.orst.edu/geowater/FX3/help/8_Hydraulic_Reference/Mannings_n_Tables.htm.

Value

a raster object of flow times (s)

Examples

plot(log(flowtimes(dtm100m)), main = "Log flow time (s)")

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