Spatial characterization of hydraulic conductivity in alluvial gravel-and-sand aquifers: a comparison of methods

For groundwater transport modeling on a scale of 10-100 m, detailed information about the spatial distribution of hydraulic conductivity is of great importance. At a test site (10x20 m) in the alluvial gravel-and-sand aquifer of the perialpine Thur valley (Switzerland), four different methods were applied on different scales to assess this parameter. A comparison of the results showed that multilevel slug tests give reliable results at the required scale. For its analysis, a plausible value of the anisotropy ratio of hydraulic conductivity (K (v) /K (h) ) is needed, which was calculated using a pumping test. The integral results of pumping tests provide an upper boundary of the natural spectrum of hydraulic conductivity at the scale of the test site. Flowmeter logs are recommended if the relative distribution of hydraulic conductivity is of primary importance, while sieve analyses can be used if only a rough estimate of hydraulic conductivity is acceptable.