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chri_and

User

Registered: 2017-07-27

Posts: 34

difference between zhydrograph and coupling

Hello everyone

I tried to model the sediment deposition in a tributary river due to a flood in the main river and had some problems with a cross section which did not have sediment at all.
I now tried to model it without the coupling but only with a zhydrograph downstream boundary (with same water level as the flood in the main river) and I had the same problem with no sediment in one cross section.

What is the difference between the coupling and the zhydrograph or does it actually do the same thing?
Does anybody have an idea where the problem could come from?

Best

Matteo Facchini

Developer

From: Trento

Registered: 2014-09-05

Posts: 284

Re: difference between zhydrograph and coupling

Hi,
where is the cross-section that is having issues?
Cheers

chri_and

User

Registered: 2017-07-27

Posts: 34

Re: difference between zhydrograph and coupling

Hi

The CS having issues is the second last.

In the meantime I run another simualtion with a different river/geometry. In this new case a tributary joins the main river at almost 90 degrees. The goal is to estimate the amount of sediment deposition in the tributary for different flood event in both rivers. I have used two approaches:
1) “zhydrograph” with a given water level at the last CS of the tributary.
2) 1D coupling using type “junction”.
Although I was able to run the simulations with both approaches, I noticed that for both there is no sediment deposition at the very last cross-section of the tributary. When using the 1D coupling is there an exchange of sediment between the different regions? Is there any difference between the two approaches? Which approach is the more suitable to get closer to “reality”?

Looking forward to hearing from you

Cheers

chri_and

User

Registered: 2017-07-27

Posts: 34

Re: difference between zhydrograph and coupling

Hello

Does anyone have any comments on my last questions?

Cheers

Matteo Facchini

Developer

From: Trento

Registered: 2014-09-05

Posts: 284

Re: difference between zhydrograph and coupling

Hi
it is quite difficult to answer such question with this little information.
For instance, without seeing your bmc file it is hard to figure out how you coupled the domains.
In the case of the zhydrograph it is hard to say what is happening without knowing about the values you use, how you calibrate it...

Anyway, my feeling is that there is (of course) a problem with the downstream boundary. I'd suggest you to run some very simple tests, maybe with a simplified geometry, first with constant discharge, then with a steps hydrograph...and so on.

Maybe you already did that, but I would start very easy to get gradually complicated afterwards

Best