topidx {topmodel} | R Documentation |
Calculation of the topographic index from a DEM raster
topidx(DEM, resolution, river = NA)
DEM |
A matrix representing a DEM with equally sized pixels and equal NS and EW resolution |
resolution |
Resolution of the DEM (m) |
river |
A matrix representing a river map (optional). All cells with values higher than 0 will be treated as river cells. |
The river map should not contain negative values
The function returns a list, containing 2 rasters. Atb are the topographic index values of each grid cell. Area contains the contributing area
Wouter Buytaert, University of Bristol, based on routines developed by the hydrology group of Lancaster University
data(huagrahuma.dem) topidx <- topidx(huagrahuma.dem, resolution= 25)$atb image(topidx)