I want to include a river as possible path in the least cost analysis, hence not as barrier yet as a possible alternative route. I read about it in Wheatley-Gillings 2002 in which the authors say that it makes by creating a central corridor with a central low value and the surroundings with an high values in order to force the estimation to choose the river as path.
I looked for it in letterature, yet I didn't find anything that could give me a detailed answer.
Does someone know how to do that and how, afterwords, to include this friction surface into a more general one so as to estimate the paths?
P.s. I use ArcGIS 10.1