Need help on Hantush equation

[tsli001]

Hi guys:

Recently I had come across on mounding analysis. And, everyone know that people are using ‘Hantush’ equation to do the analysis. But, in the formula there are two valuables I am having trouble to figure them out. To be more specify is the initial calculation without field data.1. Hydraulic Conductivity. 2. Specific Yield. Is there anyway I can figure out those two valves?

thank you.

 

[dgillette]

Those are both material-specific. Nearly any lab can do the hydraulic conductivity, a.k.a. permeability, or it can be guesstimated in granular materials without many fines within a factor of 10 by correlations with D10, but it also depends on porosity. The permeability of a formation is likely to be very anisotropic, even without much visible stratification.

Specific yield is the amount of water that drains out of one m^2 of the aquifer when you lower the water table by 1 m. It is less than the porosity because some water is held back by capillary effects. In clean gravel, it is pretty close to the porosity (up to 0.35 or so). In clay, it is practically zero, since ALL of the water is usually kept in place by capillarity.

 

[tsli001]

Thanks dgillette, for replying me. I was wondering is there any web site that can show me a table or chat that can help me on estimate those two element. Is really hard sometime to provide some number that without any back up information.

thanks

tsli

 

[fattdad]

Here's a reference that has a correlation to D20 (or D10) and hydraulic conductivity (notice the units are in 10-4 cm/sec):

http://home.comcast.net/~fatt-dad/permeability_correlation.pdf

Do a sieve, get the D20 (or D10) size and enter the chart to get the hydraulic conductivity.

For information on Specific Yield, look at Figure 2-5 at this reference:

http://www.usace.army.mil/publications/eng-manuals/em1110-2-1421/entire.pdf

Hope this helps.

f-d

¡papá gordo ain’t no madre flaca!