Vertical hydraulic conductivity of highly permeable alluvial aquifers

Researchers have often paid much attention to determining horizontal hydraulic conductivity (Kh), but careful characterization of the vertical hydraulic conductivity (Kv) of an alluvial aquifer is needed for better evaluation of hydrological processes in the saturated zone, as well as in the unsaturated zone. This paper demonstrates the Geoprobe technique combined with permeameter tests for estimation of Kv of an alluvial aquifer. Six depth-profiles of Kv values were produced for a highly permeable alluvial aquifer in the Platte River valley of Nebraska. The results of this study indicate that 1) Kv is a spatially-varied parameter both in the horizontal and vertical dimension, 2) Kv values determined using the permeameter tests are compatible to Kv determined from pumping tests and no scaling effect or measurement-method effect was observed. Thus, this study shows an alternative method that can generate more detailed information on Kv in alluvial aquifers and is more cost effective than pumping tests. Most Kv values determined from sediment cores or from pumping tests for the alluvial aquifer in the Platte River Valley of Nebraska range from 1 to 10 m/d.