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All Topics | Topic "Problems in result of WEAP model (Supply Delivered and Reservoir)"
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Author Message
Mr. Hassan Ahmadifard

Subject: Problems in result of WEAP model (Supply Delivered and Reservoir)   
Posted: 8/15/2023 Viewed: 1710 times

1. I develop a simple model in the last version of WEAP (WEAP 2023) which includes a river, a reservoir dam and two demand sites. In this model, the top off inactive of dam is equal to 3.5 MCM, the demand priorities is set to one and two and the reservoir priority is equal to 99. According to the SOP rule, the outflow of the reservoir should be zero until the dam is filled up to the volume of 3.5 MCM (MOL of the reservoir). But the results of the simulation show that in some months, despite the reservoir volume is below the MOL of the reservoir, there is a small amount of outflow from the reservoir which is allocated to the demand sites.

2. In the other month, the demands with high priority are not met 100%, but the water is allocated to the demands with low priority. By searching in the previous Topics (Topic "Reservoir Calculation (Top of Inactive, Evaporation, Allocation)",1/6/2021), this question has been answered by Ms. Anne Hereford as follows:
"Due to numerical instability issues in the LP solver, very small amounts of water (usually <1 cubic meter per timestep) are sometimes alotted to lower priority demand sites even when higher priority sites are not receiving 100% of their demand. This prevents the solver from reporting infeasibility in later iterations. (Thanks to Jack Sieber for this explanation)".
in this answer mentioned that this amount is below 1 cubic meter per timestep, but this amount (supply delivered) in the last model reaches almost 1000 cubic meters per month for the demand of 1.3 million cubic meters per month.
Could you please explain the reasons for these problems?

Best regards
Ms. Anne Hereford

Subject: Re: Problems in result of WEAP model (Supply Delivered and Reservoir)   
Posted: 10/4/2023 Viewed: 1268 times
Hi Hassan,
It's hard to say whether this might be an issue with the LP solver. If you like, send us your model through the WEAP help menu and we'll have a look.

Topic "Problems in result of WEAP model (Supply Delivered and Reservoir)"