Delineating catchments upstream of flow sites

Discussion created by aelwan1 on Dec 29, 2013
I have many flow sites and I used them to delineate catchments upstream of each flow site using Spatial Analyst Tools > Hydrology > Watershed.

As you know using this tool, you'll get the catchments delineated as shown below (Figure 1).

Is there a way to get the catchments delineated as illustrated in Figure 2? In other words, as you move downstream, the catchment of each flow site will include all the catchments upstream of this site.

Thanks in advance