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 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.
A matrix of the same size as DEM
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 http://paramo.cc.ic.ac.uk/topmodel_tutorial for examples.
sinkfill, river