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This question already has an answer here:

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.

enter image description here

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marked as duplicate by whuber Jan 31 '14 at 15:40

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

up vote 2 down vote accepted

You can achieve this with a simple model. This question was asked here, for which I give a model showing how it can be done.

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Many thanks for your answer :) – aelwan Feb 3 '14 at 8:50

Try using ArcHydo it is a much more comprehensive toolset.

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Thanks for your help. I'm using ArcHydro but I don't know which tool could delineate the catchments as illustrated in figure 2. – aelwan Dec 30 '13 at 2:30

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