Given a digital elevation model and the coordinates of the catchment outlet, this function calculates the flowlength of each gridcell to the outlet, based on a single flow direction algorithm (D8).
flowlength(DEM,outlet)A matrix of the same size as DEM
A matrix representing a digital elevation model [m] with equally sized pixels and equal NS and EW resolution
A vector containing the row and column indices of the pixel representing the catchment outlet.
Wouter Buytaert, Imperial College London, based on an implementation from the Hydrology Group of Lancaster University
The function returns the flowlength in cell size units. So you have to multiply by the map resolution to get the flow in meters.
See https://github.com/ICHydro/topmodel for examples.
sinkfill, river