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User Forum

All Topics | Topic "Current accounts"
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Author Message
Mohammed Jamous

Subject: Current accounts   
Posted: 10/7/2015 Viewed: 5719 times
I am quoting from the help manual in WEAP.
" Establishing Current Accounts requires the user to "calibrate" the system data and assumptions to a point that accurately reflects the observed operation of the system. "

Can some please explain the above paragraph? and can you please explain the idea of WEAP calibration because I totally can't get yet ?

thank you.
Stephanie Galaitsi

Subject: Re: Current accounts   
Posted: 10/19/2015 Viewed: 5585 times
Sure thing:

When you're using WEAP, you're often asking questions of what will happen in the future (since we can't go back and change the past). The current account years is meant to represent the system as it is in a point of time when you know the data that characterizes the system. I usually think of it as a very recent year, when I know:
1) The population exerting demand on the system
2) The infrastrucutre (existing reservoirs, transmission links, wastewater treatment plans, etc)
3) Agricultural catchment information (land cover)
4) Climate data

This is what the "current" system looks like, althought the need for climate data might mean your "current accounts" year is actually 2-3 years ago.

Once you have the actual data of the system, you enter it all into WEAP in the Current Accounts, and then see how the observed data (streamflow, for example) matches your modeled data. This is the calibration mentioned in your quote.

If the model matches the observed data well, you can begin exploring possible futures for your model - new infrastrucutre, changing demand patterns, and changing climate conditions. Those are the scenario years. But it's important to start off with a solid foundation in the "current accounts" year so you can ensure that your model is producing information that may actually represent reality.

If the calibration is not satisfactory, that's an opportunity to try to improve your model before you start asking questions about the future.

Good luck,

Stephanie
Mohammed Jamous

Subject: Re: Current accounts   
Posted: 10/19/2015 Viewed: 5578 times
Dear Mrs. Stephanie;

Thank you so much for such a great and helpful answers.

I have an other question please.

how to calibrate?????

I dont know how to do it exactly.
For example, in my graduation project the only thing I have to calibrate is the flow in the river of the watershed, and as I can remember the parameters contributing in the flow of the river in my case are:

1- Treated wastewater from WWTP.
2- Runoff from rain
3- Ground water base flow

For the first Factor I cant change any thing because it is a fixed amount of water that is discharged into the river.

Now considering the other two factors they depend another date like Crop coefficient, Effective Evapotranspriation, evaporation and more. (consider using the Rainfall Runoff (simplified coefficient method)

Now after running the module for the first time I am gonna get the flow from WEAP and it wont be matching the observed flow, and here starts my nightmare :( I dont know how to calibrate the module, should I take the equations (from the calculation algorithms of weap User Manual) that are used in calculating the runoff into a river and then enter them into and excel sheet then start the changing the eqation parameters until the real data fits the moduled data by WEAP.

I really dont know how to calibrate :( :( can you please help me.

Best regards




Mohammed Jamous

Subject: Re: Current accounts   
Posted: 10/19/2015 Viewed: 5575 times
By equations I mean like these ones used in the Simplified Coefficient Methods (Rainfall Runoff & Irrigation Demands Only)

PrecipAvailableForETLC = PrecipHU * AreaLC * 10 -5 * PrecipEffectiveLC

ETpotentialLC = ETreferenceHU * KcLC * AreaLC * 10 -5

PrecipShortfallLC,I = Max ( 0, ETpotentialLC,I - PrecipAvailableForETLC,I )

SupplyRequirementLC,I = (1 / IrrFracLC,I ) * PrecipShortfallLC,I

SupplyRequirementHU = S LC,I SupplyRequirementLC,I

those are from the User Manual

Stephanie Galaitsi

Subject: Re: Current accounts   
Posted: 10/20/2015 Viewed: 5540 times
Hi Mohammed,

Yes, calibrating is a very difficult process, and it really depends on the model. I would say, before you begin changing variables, think a lot about seasonality and how to best capture that. You may also want to think about which times are year are most crucial to represent correctly.

Also, just a thought, are you certain that the wastewater treatment plant always has the same amount of outflow? Assumptions like these are important to verify. Good luck.

Stephanie
Mohammed Jamous

Subject: Re: Current accounts   
Posted: 10/21/2015 Viewed: 5530 times
Thank you so much
Topic "Current accounts"