Flow Accumulation (upslope area)

Flow accumulation algorithm that routes through flats

*** Note that this file is outdated. Please find TopoToolbox, a Matlab suite of functions for topographic analysis at
https://topotoolbox.wordpress.com/ . wflowacc will be removed from the File Exchange in the future. ****
How much water flows where? Use this algorithm to calculate the upslope area of each cell in a digital elevation model.

Algorithm specifications:
- multiple flow direction
- single flow direction
- routes across flats
- calculates deterministic, randomized and random flow
- allows you to specify a weighting exponent that governs the relation flow direction - slope
- handles edge effects