Use of archydro for drainage analysis area with internal well as external drainage

[HeidiDaxberger1]

Hello everyone,
I am new to this forum and to the use of archydro as well!
I read through the tutorial of the toolbar and I am already excited what it should be able to solve. But sadly my first trails did not get me where I wanted to be.
The area what I work on includes external as well as internal drainage (an arid high plateau with salt pans where the water evaporates away).
I use an STM dem (90m resolution) resampled to 30m resolution (cubic) as base for the drainage analysis of my area which is c. 800 x 300 km.
So there should be sinks in my drainage analysis, what I know is possible with archydro, but I did not figure out yet hoe I get the once I want and fill the rest. I tried to follow th tutorial with sink prescreening and evaluation. Selecting sinks and filling , where I think might be my error in handling the tool right. I went on with calculating the flow direction with sinks and after that the flow accumulation and stream delineation. After that I was a bit lost if I have to do batch watersheds or catchments etc.
I definitely know from my trails with arcgis tools that filling all the sinks won't work because it connects streams of the left and right side of the salt pans to one stream. Also somehow my trail of calculating the sink depth never worked!
It might be due to many user problems but also there I followed a tutorial.
It would be great if anyone would have some ideas. Thanks a lot in advance for every post it only can gt better than it is now 🙂
Cheers daxerl

[HeidiDaxberger1]

One more edit: I know the location of the salt pans (sinks) so I could select them by location and group could give them a separat ID (like the is sink attribute) and fill all the others by using the tool fill sinks but not the ones with the (issink attribute). Could that work?
Thanks again!
Daxerl

[MatejCunder]

Hi,

My suggestion would be:
- create a polygon feature class with your sinks and use it in the Fillsink step as a Deranged Polygon layer
- after "Flow direction with Sinks" step you may get a raster that has other values than expected (1,2,4,8,16,32,64 and 128). The unexpected cell numbers will occure on the locations of sinks that are not correctly defined. In this case you must extend or reduce the size of the sink polygons on those locations.
- continue these steps untill you get a Flow direction grid with cell numbers 1,2,4,8,16,32,64,128 and 255, which is the cell value of the sink.

Hope this will help,
Matej

[HeidiDaxberger]

Hi Matej!
Thanks for your response!
Yeah thats how I solved it in the end.
It worked fine.
cheers Heidi

[Pedro_PabloVillegas_Yepes]

In the blog "Agua y Sig" section you will find examples ArcHydro stepper using this tool, you might find them useful.
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regards.
seorimícuaro