Subject: MODFLOW BOUNDARY CONDITION Posted: 12/19/2014 Viewed: 7949 times
Is there any way to use 'time varient head' as boundary condition in WEAP-MODFLOW linking model
Subject: Re: MODFLOW BOUNDARY CONDITION Posted: 1/20/2015 Viewed: 7769 times
it is not possible to use a time variant head boundary straightaway.
You would need to "translate" the heads into fluxes. Then, it is easiest to add the flows as wells along the boundary cells. The flow in the well-cells can be both positive or negative in order to simulate inflow or outflow.
Have a look at BGR's website for more info about WEAP and MODFLOW:
Subject: Re: MODFLOW BOUNDARY CONDITION Posted: 2/7/2015 Viewed: 7642 times
thank you Dear Markus
I did this translation between time variant head and specified flow boundary conditions in my CALIBRATING PERIODs. It works correctly, but main question is that for forecasting periods what we can do?
Subject: Re: MODFLOW BOUNDARY CONDITION Posted: 2/9/2015 Viewed: 7608 times
You would do it the same way as if you were working on a standalone MODFLOW model: You would identify the parameters that influence groundwater inflows and outflows. Then, you would change these parameters for different scenarios accordingly (e.g. abstraction from wells, recharge from rainfall, etc.).
The coupled model works in a similar manner, except that you don't need to change the MODFLOW model's well- or recharge files, but to change water demand at demand sites and precipitation at catchment nodes instead.
Example: you have a flow-boundary along 10 cells. The monthly inflow along this boundary is 10MCM.
- You would define a demand site in WEAP, name it "GW-Inflow", with a monthly demand of 10MCM.
- Connect it to an "Other Supply" node in order to ensure the demand will be fulfilled.
- Set consumption in the DS to 0% and use a return flow from the DS to the GW node that represents the Inflow-aquifer.
- Then, define those 10 boundary cells as "wells" in the linkage file.
Doing so, WEAP will "send" 1 MCM to each boundary cell (at each month, if you use monthly timesteps).
If the inflow changes over time, you could use any built-in function, spreadsheet data or script to change the demand.
Subject: Re: MODFLOW BOUNDARY CONDITION Posted: 4/7/2015 Viewed: 7226 times
Thank you Markus