Subject: Clarification on Reservoir Terminologies in WEAP Posted: 7/19/2025 Viewed: 1116 times
Dear all,
I would greatly appreciate your clarification regarding some terminologies in WEAP.
Does "Top of Conservation" in WEAP refer to the "Full Supply Level" or the "Active Storage Level"? Also, does "Top of Inactive" refer to the Dead Storage?
Additionally, what is the mathematical relationship between these values in MCM (Million Cubic Meters)?
Thank you in advance for your time and support.
Best regards,
Selam
Mr. Doug Chalmers
Subject: Re: Clarification on Reservoir Terminologies in WEAP Posted: 7/21/2025 Viewed: 1107 times
Selam,
Top of Conservation is the fullest volume that you would want to fill your reservoir- also often referred to as the "flood rule curve". If your reservoir storage fills above the Top of Conservation, WEAP will release water downstream as fast as it can, up to the Maximum Hydraulic Outflow, until the storage level goes below the Top of Conservation, regardless of if anyone needs the water downstream. This is done to avoid the water going over the Top of Storage and having uncontrolled flooding.
Top of Inactive is indeed the dead storage- it is the storage level at the elevation of your lowest outlet. If the reservoir storage hits the Top of Inactive, the water can't be released, but can still be lost to evaporation and groundwater seepage.
Note that both these parameters are optional- depending on how your reservoir is operated, you likely want to include them, but you aren't forced to. Surely the Top of Conservation would be higher than your Top of Inactive, but otherwise I'm not aware of any universal mathematical standards for these parameters. It would just depend on how your reservoir is operated for flooding, and the location of your lowest release outlet.
In WEAP, go to Help --> Search --> "Reservoir Zones and Operations" and see the illustration which shows all these parameters for more info.
Hope this helps!
-Doug
Eng. Selam Sahlu
Subject: Re: Clarification on Reservoir Terminologies in WEAP Posted: 7/25/2025 Viewed: 955 times
Dear Doug,
Thank you so much for the clear and well-elaborated explanation, and for pointing me to the Help option in the WEAP.
Thank you for your time and insights.
Selam
Topic "Clarification on Reservoir Terminologies in WEAP"
