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Delwaq and FLOW - Constituents not transported through culverts

ED
Edward Divita, modified 5 Years ago.

Delwaq and FLOW - Constituents not transported through culverts

Youngling Posts: 3 Join Date: 10/18/12 Recent Posts
Is there a way to get DELWAQ to track discharges and transport through culverts in a coupled FLOW model?

I have a coupled Flow-DELWAQ model which represents a series of ponds linked together by a system of culverts and open water channels. The preliminary results seem to show that DELWAQ is not allowing constituents to pass through the culverts, while the hydrodynamic model shows quite a lot of discharge passing through these culverts. I have tried a couple different culvert configurations and but best as I can tell the DELWAQ results seem to completely ignore all flows through the culvert structures.

Am I doing something wrong or is DELWAQ simply unable to track flows through culverts modeled in FLOW?

I am running a 2D model with online coupling and I am not using grid aggregation.
SZ
Stephanie Zeunert, modified 4 Years ago.

RE: Delwaq and FLOW - Constituents not transported through culverts

Youngling Posts: 14 Join Date: 6/2/14 Recent Posts
Hi,

I'm currently trying to couple my FLOW results with DELWAQ. I've got the same problem as Edward. DELWAQ seems unable to simulate the transport of substances through a culvert. Is this not implemented for DELWAQ or do I have to change any configurations? I couldn't find anything regarding this topic in the manuals.

Kind regards
Stephanie
AM
Arjen Markus, modified 4 Years ago.

RE: Delwaq and FLOW - Constituents not transported through culverts

Jedi Knight Posts: 222 Join Date: 1/26/11 Recent Posts
Hi,

the problem is that the two parts of a culvert need to be linked up explicitly, as this information is not transferred automatically from Delft3D-FLOW to Delft3D-WAQ. The current method works as follows:

Assign the name "INLET1" to one part of the culvert and the name "OUTLET1" to the other part. Similarly, INLET2/OUTLET2 for the second culvert and so on. That way Delft3D-WAQ can take out the mass associated with the flow on one side and release it on the other side.

Warning: this mechanism is usually used for coupling inlets to outlets, so the transport is unidirectional. I checked the source code: there is an implicit assumption that the flow is indeed from the inlet to the outlet. For a culvert this may change over time of course, so you probably need to define a similar pair the other way around, that is: for each culvert define an outlet on the location of the inlet and vice versa.

(Culverts are sufficiently rare in our projects that we have simply never gotten around to implementing a more appropriate solution.)

The alternative - which is much better in the longer run - is to define a waste load module that explicitly takes care of this type of waste loads. Not all that hard to do ;). And actually this has been the sort of things why we introduced the waste load module in the first place.

Regards,

Arjen