groundwater drawdown analysis

[eng003]

If this is not the right forumn for this I would appreciate any alternate suggestions.

I need assistance in a short term dewatering analysis. I have used a time varied computer modeled based on the modflow routine to evaluate drawdown. I have been asked by reviewer to use simple steady state calcs based on Sichardt (1928) to determine zone of influence. My questions are as follows:

1. How do you determine the time it takes to reach steady state?
2. Even with a pump capacity of say 400 gpm you will not always extract this much as the soil hydraulic conductivity limits the rate of extraction how does this factor in over time?
3. What would be any negative effect to a road bed going under rapid groundwater drawdown?

 

[fattdad]

Steady state equations do not reflect the time to reach steady state. It's an equation that shows the position of the steady state drawdown and the steady state withdrawal. You'll have to assume or estimate a few boundary conditions (partially penetrating, fully penetrating, distance to zero drawdown).

This reference provides some steady state equations for various well/trench systems.

http://i238.photobucket.com/albums/ff102/fatt-dad/IMG_5028.jpg

look at Chapter 4 for various steady-state equations.

f-d




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