I'm trying to calculate flow accumulation layer (with arcGIS) in a basin with 2 outlet points. I have used "dem reconditioning" tool to modify my dem according to a vector layer, which contains my digitized stream network. The problem is that a few km before the main river delta a diversion is constructed (for flood management) creating thus 2 riverbeds, the natural and the constructed one, resulting in two outlet points and two deltaic parts along the coastline. I'm trying to work with a specific flood event in the river and I need to calculate flow accumulation layer with these two outlet points . I've tried many things with no success.