HELP Please: DEM-based stream definition Area threshold giving 0 -0

[Shashwat Dhungana]

Hello users,

I have been stuck at the beginning for some weeks now. Your advice would be highly highly appreciated. Please!

After I calculated the Flow direction and accumulation, the Area: (0 - 0) is a cause for concern. My online searches gave me the impression that the culprit might be a faulty DEM. Therefore I used two DEMs from various sources. However, I still get the same problem.   

I can still click the Create streams and outlets button. However, I see that there are a lot of outputs (more than 1000+ in almost the same location when I do this). What could be the problem?

Despite all these, I have selected an output and tried to delineate a watershed but the following message is all I get. 

For your ready reference, a sample of my 30m SRTM DEM is shown below:

I would be eternally grateful. 

Warm regards,

SD

[Suwas Ghimire]

Hello Shashwat

Hope you are doing well. The error "object reference..." is generated because of improper loading of dem data as far as I know which might be due to to and fro working within the window. We can get rid of this by properly loading the dem data again. Second information about outlet is generated because outlet has been defined out of dem. This might be related to first error. So loading dem in proper way might resolve the issue. Please upload the discharge station point as shape file which would help you locate the outlet point precisely. After loading discharge station shapefile you can just add subbasin outlet point at your desired discharge station and define it as whole watershed outlet by just selecting it. Hope this would be helpful.

Thank you!

Suwas

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[Shashwat Dhungana]

Hello Suwas,

Many thanks for taking the time out to get back to me. Your comment was very helpful. Regarding my probelm, I discovered that the issue was with the way the DEM was projected. As soon as that was amended, the errors disappeared. 

Cheers,

Shashwat 

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