Hi, recently my colleagues hydrologists asked me whether it is possible to create basins of similar area using GRASS. Let's say you have DEM available for area of interest and want to create basis of area size 4-5 km2. Do you have any idea? Thanks! Ma -- Martin Landa http://geo.fsv.cvut.cz/gwiki/Landa http://gismentors.cz/mentors/landa