The Importance of Prior Geologic Information on Hydraulic Tomography Analysis at the North Campus Research Site (NCRS)

Abstract

The purpose of this study is to investigate the importance of prior information about hydraulic conductivity (K) by Kriging, using point K data and/or residual covariance, on improvements of K estimates at the North Campus Research Site (NCRS). Among many methods that can characterize the mean or detail distribution of hydraulic conductivity (K), the Cooper-Jacob straight line solution, Kriging using point K data, single-well pumping tests inversion and Hydraulic Tomography (HT) have been compared in this study, using the head data collected from 15 cross-hole pumping tests collected at NCRS, where 9 existing wells were installed with packer system and the pressure responses at different intervals in different wells were monitored with transducers. It is found that the HT method, which fuse all the available pumping test data, yields more accurate and consistent results. However, many studies have indicated that the hydraulic data combined with geologic investigation will improve the HT estimates. Thus, in this study, hard data of K obtained by permeameter (227 data points) are brought in using Kriging and combined with HT to yield better estimate K field. Moreover, the validations of unused tests indicate that the estimated K obtained using collected K information makes more accurate predictions.