Watershed

[Michel Wurtz - LTE]

Hello,

I need a grass program that can give me, for any location on an
elevation model, which pixels are contribution to the water flow.
r.watershed is not exactly what I want, because you cannot choose
the point where your watershed ends (I have several mesure and
simulation along a river, and look for contributing area at each
location)

Does anybody have such tool or any other idea ?

-- 
Michel Wurtz    ENGEES - Laboratoire Territoires & Environnement
                1, quai Koch - BP 1039, F-67070 STRASBOURG cedex
                Tel: +33 03.88.24.82.45  Fax: +33 03.88.37.04.97