Ponding effect?

[Niguse Abebe]

Hi Tom and members,

I'm experiencing a ponding effect in 'reach mode', even though outlet is at a lower elevation, water is not leaving. Lowering it further didn't help. Extending the outlet works, but causes unwanted part erosion/deposition.

Any quick solution to allow water to leave the outlet, please?

Thanks!

Best regards,

Niguse

[Tom Coulthard]

Hi Niguse - the outlet has to be directly connect to the edge of the DEM. Water will not move through nodata (-9999) cells - this may be the issue as you mentioned extending the outlet (to the edge?) works.. 

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From: caesar-...@googlegroups.com <caesar-...@googlegroups.com> on behalf of Niguse Abebe <nigus...@gmail.com>
Sent: Wednesday, January 22, 2025 11:20:01 AM
To: caesar-lisflood <caesar-...@googlegroups.com>
Subject: Ponding effect?

 

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[Niguse Abebe]

Thanks for the respond.

The Reach DEM was clipped using the buffered polygon as you can see screenshot, water is not leaving. My reach DEM interest point doesn't fit with the CL window edge, (I don't know why). Does the outlet DEM should fit with CL visual page edge?

[Tom Coulthard]

Yes - has to be at the edge of the image. 

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From: caesar-...@googlegroups.com <caesar-...@googlegroups.com> on behalf of Niguse Abebe <nigus...@gmail.com>

Sent: Wednesday, January 22, 2025 4:47:29 PM
To: caesar-lisflood <caesar-...@googlegroups.com>
Subject: Re: Ponding effect?

 

To view this discussion visit https://groups.google.com/d/msgid/caesar-lisflood/7de8da46-d50a-4afb-946f-04595aeb7ca6n%40googlegroups.com.

[Niguse Abebe]

Thanks! Does it matter if the DEM is arranged following the stream centerline (irregular shape) as shown in the previous screenshot? If I make it rectangular, it will increase the number of unwanted cells, potentially slowing down model runtime.

[Tom]

Not quite sure i understand - but I'd suggest just cropping the DEM where the nodata cells start.. e.g. take away the first 20 (or however many there are) rows.