Subject: Different Maximum Hydraulic Outflows for different outflows of a single reservoir Posted: 1/15/2018 Viewed: 827 times
My first question is that is it possible to have 2 or more outflows from a single reservoir?
And moreover, I was wondering if it is possible to assign different values of Maximum Hydraulic Outflows (MHO) for different ouflows (e.g., diversion channel, transmission link, rivers, etc.) of a single reservoir.
Ms. Stephanie Galaitsi
Subject: Re: Different Maximum Hydraulic Outflows for different outflows of a single reservoir Posted: 1/22/2018 Viewed: 811 times
You'll see that when you build a reservoir, there is a single place where you can enter data for "maximum hydraulic outflow" of the reservoir itself.
From the Help menu "Reservoir Maximum Hydraulic Outflow": [the maximum hydraulic outflow is the] maximum reservoir outflow during a timestep due to hydraulic constraints. Typically this will be a function of reservoir elevation at the beginning of the timestep. [There is] no constraint during timesteps when the reservoir is completely full; water will overtop the reservoir at an unlimited rate. Normally, when there is no maximum hydraulic outflow constraint, WEAP will never allow reservoir storage to exceef the top of the conservation zone [see reservoir operations data]. However, if there is a maximum hydraulic outflow constraint specified, it is possible for the reservoir storage to exceed the top of the conservation zone in timesteps where releases from the reservoir equal the maximum hydraulic outflow.
If you want to have multiple water transfers using the water that is released from the reservoir, you can create your reservoir on a river, and you can build directly downstream of the reservoir (where the water is released) transmission links to your various demands, and those can have limited volume flow (you can enter data for the transmission links "maximum flow volume").
Would this option correctly simulate your existing system?
Mr. Kasra Keshavarz
Subject: Re: Different Maximum Hydraulic Outflows for different outflows of a single reservoir Posted: 1/30/2018 Viewed: 767 times
Thanks for the note. Let me explain the system that I am trying to model. Just imagine that a lake (reservoir) have two different control structures at two different places. In this case, each control structure can have different outflow capacities based on the elevation of the reservoir.
In the case of putting various Transmission Links or Diversion Channels just below the reservoir's single outflow, I guess I should sum the Maximum Hydraulic Outflow (MHO) of the two control structures of the reservoir (which are calculated based on the reservoir's elevation in the previous time-step). Then the calculated MHO should be assigned as the final MHO of the reservoir. Then I should be able to put various Diversion Channels just below the reservoir. Is this approach correctly resembling my system?
Ms. Stephanie Galaitsi
Subject: Re: Different Maximum Hydraulic Outflows for different outflows of a single reservoir Posted: 2/1/2018 Viewed: 699 times
I would concur that you should start by summing the MHOs (since they are dependent the elevation). Then you can build a diversion link just below the reservoir (on the river) and use the parameter "fraction diverted" to specify the proportion of water that would leave the reservoir through one of the control structures. The reservoir leaving the other control structure would be represented by the river itself.
If they have different outflow capacities based on the elevation of the reservoir that includes different PROPORTIONS of capacities for different elevations of the reservoir, you use embedded "if" statements about the reservoir elevation in the previous time step.
Something like this
If(PrevTSValue(Supply and Resources\River\Main River\Reservoirs\Reservoir:Storage Elevation[m])>=30,0.8,PrevTSValue(Supply and Resources\River\Main River\Reservoirs\Reservoir:Storage Elevation[m])>=20, 0.7,0.6))
What I've written here is:
If, at the end of the previous time step, the reservoir elevation is more than or equal to 30 m, 80% of the water goes to the diversion. If the elevation was between 20-30 m, 70% of the water goes to the diversion. If the elevation was less than 20 m, 60% of the water goes to the diversion.
So it can be as flexible as you need it to be to divide the water leaving the reservoir.
Topic "Different Maximum Hydraulic Outflows for different outflows of a single reservoir"