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Water shade delination

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#1
yeneneshabebe

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Dear all,
I was trying to delinate water shade boundary from AsterGDEM 30m elevation dataset for microcatchemnet level using ArcSWAT. The watershade boundary which is generated using one outlet point for the area didn't include the points (The 5 red points in the atached image) which are considered as head flow or starting points for the watershade. The watershade boundary starts to the northwest of the red points from the purpule point. The problem is the flow direction on the field observed by the hydrologists and on the output from the DEM is deifferent. According to their observation the flow starts from the red points and continue to north west towards the outlet. In the output the flow dirction for the red points is towards south. Is there any idea about this ? What about the accuracy of AsterGDEM 30m for flow direction and watershade boundary delination. Some say there is a flow direction variation in the DEM output and on the ground on some streams when you use this elevation dataset is that true? Any comments, suggestion and solutions....??


Hope to get some help on this issue


It seems I am not alowed to attach the file . But hope you understand the problem

Yenenesh

#2
Hans van der Maarel

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It seems I am not alowed to attach the file . But hope you understand the problem


How big is the file? You're a validated member, so it should work as long as it's an allowed file type and it's under 10 Mb.
Hans van der Maarel - Cartotalk Editor
Red Geographics
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#3
yeneneshabebe

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Dear Hans,

It is 1.04mb very small and word file just screen shot.

But this time also it says U 'Upload failed. You are not permitted to upload this type of file'


Yenenesh

#4
Hans van der Maarel

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It is 1.04mb very small and word file just screen shot.

But this time also it says U 'Upload failed. You are not permitted to upload this type of file'


Word is indeed not supported (primarily because it requires the launching of another application to view) Try saving it as a JPG or PDF, those are allowed and most browsers will be able to handle those just fine.
Hans van der Maarel - Cartotalk Editor
Red Geographics
Email: hans@redgeographics.com / Twitter: @redgeographics

#5
yeneneshabebe

yeneneshabebe

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Dear all,
I was trying to delinate water shade boundary from AsterGDEM 30m elevation dataset for microcatchemnet level using ArcSWAT. The watershade boundary which is generated using one outlet point for the area didn't include the points (The 5 red points in the atached image) which are considered as head flow or starting points for the watershade. The watershade boundary starts to the northwest of the red points from the purpule point. The problem is the flow direction on the field observed by the hydrologists and on the output from the DEM is deifferent. According to their observation the flow starts from the red points and continue to north west towards the outlet. In the output the flow dirction for the red points is towards south. Is there any idea about this ? What about the accuracy of AsterGDEM 30m for flow direction and watershade boundary delination. Some say there is a flow direction variation in the DEM output and on the ground on some streams when you use this elevation dataset is that true? Any comments, suggestion and solutions....??


Hope to get some help on this issue


It seems I am not alowed to attach the file . But hope you understand the problem

Yenenesh

Attached Files



#6
yeneneshabebe

yeneneshabebe

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It is 1.04mb very small and word file just screen shot.

But this time also it says U 'Upload failed. You are not permitted to upload this type of file'


Word is indeed not supported (primarily because it requires the launching of another application to view) Try saving it as a JPG or PDF, those are allowed and most browsers will be able to handle those just fine.



Dear Hans,
I have uploaded the image. Any solutions on the problem?
Yenenesh

#7
Hans van der Maarel

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I have uploaded the image. Any solutions on the problem?


I don't to be honest, I don't know anything about watersheds, but hopefully one of our other members is able to help you out. I think a lot of people are enjoying the christmas holidays though.
Hans van der Maarel - Cartotalk Editor
Red Geographics
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#8
Sab

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I usually use GRASS GIS to do that, where you can change some hydrological parameters to fine-tune the output.
It is very fast and as a matter of fact we have turned the whole process to a Web Processing Service:

http://webgis1.lutraconsulting.co.uk/catchment_finder/




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