Subject: Water Right Modelling Posted: 1/20/2011 Viewed: 19458 times
I'm using WEAP to model reservoir operations for a reservoir yield study. The res has total capacity of 4400 AF with no flood control component. The water rights include: 1) 1800 AF/yr of diversion to storage between October and May which may be done as quickly or slowly as needed (i.e., we'll usually store water as quickly as possible) 2) 5.55 cfs (11 AF/day) of direct diversion any time which we'd rather use before the stored water. However, the inflow typically goes to zero for several months of the year so no direct diversion is available for those months. 3) Maximum total diversion (storage and direct) or 3500 AF/yr. 4) Maximum withdrawal from storage of 1800 AF/yr. I also have six demands.
I expect to model the system as two off-line (local) reservoirs. The direct diversion res will have a capacity of zero and each demand site will be connected to it with a 1 for supply preference. Downstream of this will be the storage res with a capacity of 4400 AF and supply preference of 2.
How do I implement the maximum diversion to storage, total diversion, and withdrawal from storage?
I've considered and rejected limiting the transmission link flow to the storage res (which I will be using for the direct diversion res) since I can't write expressions in the individual monthly maximums. I also don't think I can use the "operations" parameters for the same reason. I think I might be able to use a downstream flow requirement that ties back to previous res capacity but I'm still pondering the needed code snippet.
Any thoughts and input would be greatly appreciated.
Subject: Re: Water Right Modelling Posted: 2/7/2011 Viewed: 19432 times
Hi Glenn, I am a bit confused by the two diversions rights. Is the 1800 af/yr diversion to storage, from another storage source; and is the direct diversion, the diversion from tributary streams above the reservoir? Do you have a schematic or a weap area that might help me understand your modeling problem? David Yates
Subject: Re: Water Right Modelling Posted: 2/7/2011 Viewed: 19426 times
The real system is an online reservoir. All demands are actually supplied out of the reservoir. As I understand it, the regulatory definition is that diversion to storage is any water stored in the reservoir and not used in the month it comes in, while direct diversion is water actually supplied during the month it comes in. All the water that's not diverted, either directly or "to storage," must be released.
Obviously, I want to maximize the amount of water I store which means I want to fulfill demands with direct diversion first and fill the res as quickly as I can.
I've put in-stream flow requirements between the withdrawal and return nodes for each res and begun writing equations for them that will incorporate the water right limits (I hope), but I'm still trying to wrap my head around what I actually want to do. Also, trying to get the units to work has been a huge pain.