maximum hydraulic conductivity exists?

Hi groundwater modelers:

A question for you all. If a surface water body is included within a model domain, people usually assign a very big hydraulic conductivity to it, assuming that this big hydraulic conductivity will make the resistance to groundwater flow negligible. My question is: Is a very big hydraulic conductivity, say 100 m/s, physically feasible? If we use the most common method to measure the hydraulic conductivity of a medium, I would guess the biggest hydraulic conductivity could be obtained if there is only one tiny smooth sand (and air so that you still think it is a porous medium in a limit sense) in the vertical column. what value of hydraulic conductivity do you think you could get for this medium?  sqrt(2*g*h)?

Any comments are welcome.

Quinn

There is no need to physically represent the K of open air when model elements are used in this manner to represent open water bodies (e.g. lakes).  It is only necessary to make the K significantly greater than the adjacent porous media so that gradients in the lake will be flat compared to the adjacent sediments.

Also don't forget to assign Sy =1.