Regarding reservoir outflow

[Kaushal Garg]

Dear SWAT users

I have one query regarding reservoir outflow and SWAT modeling strategy. I have one reservoir some where in middle across the river. I have reservoir outflow information only for a limited period but I wanted to have simulation for long period of time. I wanted to have simulation for a period where reservoir outflow information is not available then how can I make my modeling protocol.

manual shows that there are 4 ways to define reservoir outflow in project.

Outflow simulation code: 0 : uncontrolled reservoir

Outflow simulation code: 1 : Measured monthly outflow

Outflow simulation code: 2 : Simulated controlled outflow

Outflow simulation code: 3 : Measured daily outflow

 

I believe that I should use second or third option for my problem. But the terminology is not much clear to me. Can anyone please help me and elaborate more!

Thanks in advance.

 

Regards, Kaushal

 

[Nathan Bosch]

Kaushal,

My initial advice for you is to use the third option as you have them
listed. This is also called Targeted Release because you specify the
target volume of the reservoir. When you have times with high inflow
into the reservoir, the volume swells, and you set a number of days for
the reservoir to get back to the target volume once again. I use it
for reservoirs managed to be "run-of-the-river" meaning that they are
not supposed to alter the flow at all (inflow=outflow). I set the
NDTARG to 1 day and have the target volume be the same as the principle
volume of the reservoir. There is a nice section explaining the
outflow simulation options in the SWAT theoretical documentation that
you should read. It is hard for me to know exactly how to advise since
I am not familiar with the specific reservoir you are modeling, but I
hope my thoughts are helpful to you.

Thanks,

Nate

Quoting Kaushal Garg <garg...@gmail.com>:

-------------------------------------------
Nathan S. Bosch, Ph.D.
Research Fellow
School of Natural Resources and Environment
University of Michigan

[Kaushal Garg]

Thank you Nathan for your valuable advice regarding my query.

regards, Kaushal

 

[Kaushal Garg]

Dear Nathan

As per your suggestion I used targeted release option to model my reservoir in SWAT. I kept target reservoir volume as equal to principle volume and NDTARGR=1. Now I find some other problem in results.  Model is not able to hold any amount of water into reservoir. Inflow coming to reservoir is directly going out from the reservoir without filling it and reservoir volume showing almost nil.
 

I have attached one reservoir input file as for your reference. Would you please help me again and probably suggest any solution to fix this problem.

Thanks and regards,

Kaushal

 

On 5/6/08, Nathan Bosch <bos...@umich.edu> wrote:

[Raktim Haldar]

Hello,

I had a question regarding reservoir ourflows.

In SWAT does reservoir outflow gets added to reach? or is is assumed to get out of the river system (for irrigation)?

[Natalja C.]

Hello,

It depends on how your setup. But if you mean the basic "outflow" and not the water withdrawal, then yes - it gets added to the reach.

You can check this in the fig.fig file, where the reach is being supplemented (add command).

Natalja

[Jim Almendinger]

In SWAT, outflow from a reservoir is added to the flow of the next downstream reach.

-- Jim

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James E. Almendinger, PhD

Director, St. Croix Watershed Research Station

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Email: jalmen...@smm.org