topidx {topmodel} | R Documentation |
Calculation of the topographic index from a DEM raster
topidx(DEM, resolution, river = NULL)
DEM |
A matrix representing a digital elevation model with equally sized pixels and equal NS and EW resolution |
resolution |
Resolution of the digital elevation model (m) |
river |
A matrix representing a river map (optional). All cells with values higher than 0 will be treated as river cells and are not included in the calculations. |
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, Imperial College London, based on routines developed by the hydrology group of Lancaster University
See http://paramo.cc.ic.ac.uk/topmodel_tutorial for examples.
data(huagrahuma.dem) topidx <- topidx(huagrahuma.dem, resolution= 25)$atb image(topidx)