watershed using hydrology

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10-05-2021 12:20 AM
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RenMauriceAlaba
New Contributor

Good day to all.

I have a question about creating watersheds in ArcMap.
I am working on a watershed delineation for a certain place here in the Philippines. I am using a SRTM 1arc Global tif file from USGS. My question is: am I doing something wrong because the output keeps on creating solid colors? These colors will eventually turn into lines after I do Flow Accumulation from Hydrology. Did I choose the wrong file?

I am attaching a screenshot of my work.

Here is my workflow
-tif file to layers
-Arctoolbox > Hydrology > Fill
-Arctoolbox > Hydrology > Flow Direction

I hope you guys can help me.

What kind of file do I need to download?
Can you spare me some sites where I can download them?


Good day to all!

3 Replies
DrVSSKiran
Occasional Contributor II

Can you please share the screenshot of the input dem file. Also, I would like to suggest you to test some other datasets.

RenMauriceAlaba
New Contributor

Hi @DrVSSKiran,

Thank you for your response.

Attached here is the screenshot of my DEM uploaded in Arcgis.

0 Kudos
ThomasHamill
Occasional Contributor II

Contiguous/uniform areas in the Flow Direction result usually mean the surface is flat (like open water), but it might be some other artifact in your original DEM or Filled DEM because those triangle-like areas suggest there was null/no-data cells in your original input raster.

You're correct that the Flow Accumulation (after Flow Direction) will turn the result into lines--you may just have to adjust the symbology (two bins, make one black and one white) to see the linework.

Kindest Regards,

t