How to simulate the effect of water withdrawal in river

EFDC_Explorer
1

Hi there,
I have a EFDC model simulating the hydrodynamics of a large river. There are some oil sands companies along the river taking certain amount of water every day. Now I want to see how these water withdrawals effect the water level.

So my question is how to set up the Boundary Conditions for water withdrawal. I have tried the “withdrawal” BC. However, the EE keeps asking me to add “return cell” (I think it is for mass conservation purpose) which I don’t really need to because the companies take the water out and don’t give them back.

Can anyone give me some idea about this?

Thanks

Emily

2

Hi Emily,

If you are only interested about the withdrawal and not return, you can just use flow boundary and assign negative flows for water going out of the system. If you are simulating water quality / toxics you don’t need to provide outgoing concentrations as they will be calculated internally in the model. So, just go ahead and assign flow boundary for withdrawal. If you know what depth the flow is being extracted / withdrawn, you could specify only those particular layers.

Thanks.

Janesh

3

Hi Janesh,

Thanks for your solution. I use the negative flow as BC, and it works.

I have one more question. In addition to the water level, I also want to see the discharge. I am wondering how to export discharge data from EFDC.
From the viewing options, there is no discharge option I can choose.

Looking forward to you reply.

Emily

4

Hi Emily,

In order to extract the discharge from a cross-section you would need to use the “Water and Flux tool” on the view plan as shown in figure below:

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You will need to create the polyline where you want to extract the discharge. To create a polyline use the penline like icon on the figure above. Then choose “Velocites” in Viewing options. The flux calculation options window looks like following:



If you would like to extract time series then check the “Show TimeSeries” button. This is how you can extract the discharge data. You can use the flux line on calibration tool and use the calibration tool as well.

Thanks.

Janesh