- June 23, 2014 at 4:17 pm #3645
I am doing some simulation of hydrodynamics with EE. The results of water levels and temperature is good in one year but not so good in another year. I only know we can change bottom roughness, time step.etc. But the result seems no better. What parameter effect water levels and temperature a lot?
I want to know what parameters I should adjust, and what’s the recommended range of each parameter? (My study area is a reservoir, 188km2, about 30m deep)
And we should also change values of “turbulent diffusion” or “turbulent intensity” when we calibrate our model? or we have a recommended value?
I am looking forward to your answer. Thank you very much!
DaisyJune 23, 2014 at 5:59 pm #3646
The common parameters that can be tuned up to calibrate the EFDC model are as follows:
1) Bottom roughness height
2) Wind drag coefficient
3) Solar Radiation (increasing or decreasing)
4) Wind sheltering
5) Smagorinsky Coefficient (c)
6) Vertical Eddy Viscosity
7) Fast Solar Radiation attenuation coefficient
8) Initialize thermal thickness of bed and bed temperature
9) Heat transfer coefficient between Bed / WC
Calibration Parameters and their Range[table][/table]
Calibration Parameters Calibration Range
Smagorinsky Coefficient 0.1 – 0.25
Roughness height 0.01 m – 0.1m
Wind sheltering coefficient depending on the location
Vertical Eddy viscosity 1.0E-7 to 1.0E-3 m2/s
Horizontal eddy viscosity 0.5-20 m2/s
(usually 10^2-10^7 times greater than vertical eddy viscosity)
Heat transfer coefficient between bed/ WC typically 0.3
You also need to look your data such as vertical profiles and time series to see whether you have large stratification or very small stratification. If you have large stratification in your observed data but you are getting well mixed condition in your model results you might need to play around with the vertical eddy viscosity.
For water surface elevation, the key parameters are smagorinsky coefficient and roughness height.
I hope this helps.
Janesh D.June 25, 2014 at 5:00 am #3647
Thank you so much for your detailed response! It really helps a lot! But I still have a little doubt as follows.
(1) I can’t find where to change the Wind drag coefficient? Could you show me a printscreen of that?
(2) When I set the value of Smagorinsky Coefficient, I should select “activate HMD with Smagorinsky” or “activate HMD with Smagorinsky, wall drag and WC Diffusion”?
Thank you very much!
Ravina.June 27, 2014 at 5:31 pm #3648
1. Please find the attached figure to see where you can change the wind drag coefficient. To find the atmospheric parameters window you need to define the atmospheric series first.
2. When you select the Smagorinsky coefficient, you can select “activate HMD with Smagorinsky” option.
Janesh DevkotaApril 15, 2019 at 2:15 pm #5913
Your previous post introducing the parameters and their ranges is really helpful, but how can I reference them?
Do you have any published form showing them?
Additionally, what can be a reasonable range for vertical molecular diffusivity (m2/s), called ABO?
MinjeongApril 16, 2019 at 1:00 am #5916
Janesh is no longer a moderator and does not check the forum anymore, so I will try to address your question.
The values Janesh gave are a good general guide, and I have used these myself on several occasions to get started on model calibration. However, we don’t offer these as a general guide because they are ultimately still calibration parameters. You may find that some of the value ranges he has provided simply will not work if your model, so don’t take these ranges as anything more than suggestions.
Regarding the ABO value, generally, this value should be 10 – 100x less than your AVO value.
Hope that helps.
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