Author Topic: Saltwater intrusion  (Read 398 times)

selva191

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Saltwater intrusion
« on: August 12, 2015, 08:13:08 pm »
Hi,

I am new to FEFLOW and trying to setup saltwater intrusion for variable density model with simple 2D vertical flow rectangular aquifer. I have checked out "invoke Boussinesq's approximation" box and defined density ratio as 1.025. Boundary conditions are specific head and specific concentration boundaries. However, with longitudinal dispersivity 10 m and hydraulic conductivity 44.2 m/day I cannot see any intrusion. Do I need to setup any other parameters? Please help me if there is any tutorial for this.

Thank you,
Selva

Peter Schätzl

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Re: Saltwater intrusion
« Reply #1 on: August 17, 2015, 10:41:40 am »
Selva,
You may have a look at the Henry example which is very simplified, but based on the same principle. Let us know if you still encounter problems. Once you've installed the FEFLOW Demo Data package, you'll find the Henry benchmark in C:\Users\Public\Documents\WASY FEFLOW 6.2\demo\benchmarks\femdata\bench_henry.fem (path for Windows 7, can be different on other operating systems).
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selva191

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Re: Saltwater intrusion
« Reply #2 on: August 25, 2015, 02:49:38 pm »
Peter,

Whether the seaside boundary condition for an confined aquifer should be in pressure form or head*1.025. And what should be the initial head inside if I want to my initial head to be MSL. In Henry problem why the seaside hydraulic boundary is given a linearly increasing function to 0.025. I could not understand how it represents the hydrostatic head.

Thanks,
Selva.

Peter Schätzl

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Re: Saltwater intrusion
« Reply #3 on: August 25, 2015, 06:53:24 pm »
FEFLOW uses the concept of an 'equivalent freshwater head' where the hydraulic head is expressed in terms of an equivalent head at freshwater conditions. Thus in case of saline groundwater, hydrostatic conditions result in an equivalent freshwater head that increases linearly with depth. The same concept has to be applied to initial head throughout the model domain. So in FEFLOW 'head' never means 'saltwater head' but always 'equivalent freshwater head'.
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selva191

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Re: Saltwater intrusion
« Reply #4 on: August 25, 2015, 08:23:47 pm »
Thank you! Just seen the white paper for hydraulic head boundary in density-dependent flow.

I have one more question:

How to define tidal boundary condition? Do I need to define different time series for each node of the seaside boundry since with varying time tidal water level might go below the nodes in inter tidal zone?

From previous post I have seen there is a plug-in for varying saltwater head.

http://forum.mikepoweredbydhi.com/index.php/topic,1075.0.html

Do I need to get the plug-in below or FEFLOW 6.2 included the update for the same?

Thank you,
Selva

razipv

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Re: Saltwater intrusion
« Reply #5 on: September 06, 2018, 05:27:08 am »
please answer for above question

razipv

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Re: Saltwater intrusion
« Reply #6 on: October 09, 2019, 06:01:06 pm »
Thank you! Just seen the white paper for hydraulic head boundary in density-dependent flow.

I have one more question:

How to define tidal boundary condition? Do I need to define different time series for each node of the seaside boundry since with varying time tidal water level might go below the nodes in inter tidal zone?

From previous post I have seen there is a plug-in for varying saltwater head.

http://forum.mikepoweredbydhi.com/index.php/topic,1075.0.html

Do I need to get the plug-in below or FEFLOW 6.2 included the update for the same?

Thank you,
Selva

Coastal_

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Re: Saltwater intrusion
« Reply #7 on: October 14, 2019, 03:44:21 am »
Short answer; no, you can't (at least not easily).

Long answer; you need to try and program it yourself via the IFM plugins or try to get this plug-in working properly (which is not simple).

https://forum.mikepoweredbydhi.com/index.php/topic,21058.msg27689.html#msg27689