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Problems with Flow Direction and Flow Accumulation

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01-01-2021 10:32 AM
AndréSouza
New Contributor

Hello,

I'm having troubles to generate the drainage network using the Flow Direction and Flow Accumulation tools. The Flow Direction creates wrong results and, consequently, influenced in the Flow Accumulation results. Concerned to Flow Accumulation, the results show "flows" totally wrong in relation to the streams and also do not is generate the "flow" to the main river.  I attached 3 figures showing it.
Some informations: I've used the NasaDEM with 30m of the spatial resolution and the procedures followed were: 1) Fill; 2) Flow Direction; 3)Flow Accumulation. I'm using Projected Coordinates SIRGAS 2000 23S (standard for Brazil) and ArcGis 10.8.

A few months ago I read in this community about adjustments that could be made by "Environments", but I didn't save the page for further reading. It would be to solve the problems or there is some other way. Could someone help me, please?

1 Reply
Robert_LeClair
Esri Notable Contributor

Andre - I start with the caveat I have not done Flow Direction / Flow Accumulation in a super long time.  Question I'd start with is are you following the workflow listed in the Understanding Drainage Systems part of the ArcMap Help located here?  It provides a good start on how to generate the output.

Additionally, a customer made this YouTube video on how to create a Drainage Map - good workflow here too.

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