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Hello!

I am wondering if there is an easy way to calculate to water volume of each node for a 2D-result that I have. I know that the option exists in Fudaa and BK to do this for the entire mesh or portions of it. I would need to have the data specified for each node, either as a variable or in table would work great. The results will be evaluated on a monthly average so no time steps in the result.

Running the model again with an added output is unfortunately not an option this time.

Best regards

Jonas

Hi

Compute a volume of a node has no sense!
You could compute the volume on an element, not on a node.
Maybe you should try to explain a little more what you want...

Regards

Hello!

Yes of course, i realize that a node does not have a volume. The question was ill posed on my behalf, sorry.

However i was thinking of making an estimation of how large volume each node represents, if that makes sense? I will try and explain what I am attempting to do and pose new questions :)

Basically I have a lake, I have results for water depth and tracer koncentration in the lake, I need to make an estimation of what portion of the lakes volume that has a tracer concentration above a certain threshold.

Since it is possible to select a number of nodes in Fudaa and calculate a volume, I was looking to do something similar. How is this achieved in Fudaa?

Example of what I would like to achieve:
In May, X% of the lakes volume had a koncentration of tracer Y above 400.

This could offcourse also be solved by exporting the average koncentration per element and the average volume per element. However so far it has been my understanding that most of the exports from BK is at node level since they contain the info. But: Is it possible to export a list of all the elements contained within a polygon? The list must contain average tracer koncentration, average depth and surface area for each element.

I think this could be achieved through exporting, and interpolating using GIS but it would be great with a simpler way!

Dear Jonas,

There should different means to achieve the computation you want.

If you want to compute in 2D the volume in the domain where %tracer exceeds a thereshold, you can try PyTelTools.
If you are not used to code in Python, simply use the GUI. To compute this volume, you have to use 2 tools (from the "classic interface"):

1) Compute a new conditional variable with the "Variable Calculator"
Basically you clip water depth with a condition of the concentration.

Here is a dummy example to help you (as the tool is not yet documented) :


You have of course to adapt the variable name M and the threshold value of 0.5 to your need.

If you want to avoid a part of the domain, such as tidal flats with high values of concentration, you can try to :
* add a condition on H for example (with an "AND" operator)
* add a spatial condition (define zones with polygons)

2) Compute the volume of this variable
Simply compute the volume of this new variable to get the volume in m3/s (integrate volume between new variable and 0).

These operations can be done once on a file containing all the relevant frames (=times serie).

Hope it helps.
Luc

Hello!

Thank you for the helpful suggestions and for taking the time to write new tools! I will take a look at the tools, I was not aware of them before :)

I have a few things to try now, I like the fact that tidal flats can be completely excluded this way rather that just having a low "weight" due to shallow depths. For this simulations, the lake is a mountainous lake with quite small floodplains so I do not believe they will have a significant impact on the volume. It will be interesting to see if this hypothesis is correct!

Best regards