I have two layers, one with rivers and one with watersheds. I am interested in having 1 river within each polygon, but my problem is that I have too many watershed polygons. Therefore I wish to dissolve the polygons that dosen't have a river with the neighboring polygons that does have them. How can this be done?
I assume you know which whatersheds don't contain a river already; you can give this a try: - select all whatersheds that don't contain a river; - run Eliminate tool to merge each of them with a remaining watershed by the area/border option you specify.
Test a few features first to see if you get what you expected.