Well,

the question means you have hydraulic conductivity and depths data, if this true, then the;

Best fit line relation (1st order equation) between K and Depth values is the simple equation.

Regards

Thanks for answers. I mean, if I have the hydraulic conductivity of a fractured rock measured near the surface, how can I calculate the hydraulic conductivity conductivity of this rock for a depth of 200 m.

Decreasing the hydraulic conductivity of an aquifer with depth is a result that we try to know. The hydraulic conductivity (K) may decrease or increase with depth depending on the aquifer physical properties and others factors. The grain size analysis for the different aquifer horizons is the simplest method to know the changes in K values with depth. It is a simple method and costs nothing,. More details about how to apply this method are found in the attached paper.

Well,

In this case, you must doing pumping test at the suggested depth.

Regards

I agree with Bayan Hussien & Salah Abdelwahab El-Sayed

Layer based pumping test or grain size analysis are among the techniques to estimate hydraulic conductivity values at specific depth. There is no such a consensus on the relation between depth and hydraulic conductivity. It's totally the property of the earth materials at specific depth and the fluid passing through. So, I don't think the hypothesis is write in the first place. Hydraulic conductivity doesn't depend on depth, it rather depends on the physical property of the earth materials right at the depth of interest.