Estimation of watershed-scale hydraulic conductivity for two watershed sites using GFLOW

Abstract

D. Goswami1, P. K. Kalita2, E. Mehnert3

(1. S.W. Florida Research and Education Center, University of Florida, Immokalee, FL 34142;
2. University of Illinois, 1304 W. Pennsylvania Avenue, Urbana, IL 61801;
3. Illinois State Geological Survey, 615 E. Peabody Drive, Champaign, IL 61801)

Abstract: For hydrologic and water quality studies, proper estimation of the hydraulic conductivity of the study site is very important.  The hydraulic conductivity values determined in the laboratory are usually lower than those observed in the field. Hydraulic conductivity increases with measurement scale.  This increase with larger scale is the result of spatial heterogeneities and is described as scaling-up of hydraulic conductivity.  Field and laboratory experiments to determine hydraulic conductivity values for large areas are expensive and time consuming.  Modeling may be a practical option to estimate hydraulic conductivity when the study area is large.  GFLOW, which is an analytical element model, was used to estimate the hydraulic conductivity values for two watershed sites in Illinois, namely the Big Ditch watershed and the Upper Embarras River watershed.  For each site, heads in shallow observation wells and stream discharge were used to calibrate the model.  The calibrated hydraulic conductivity values for the Big Ditch and Upper Embarras River watersheds were 4.05E-04 and 4.86E-04 m/s, respectively.  For watershed-scale studies, the hydraulic conductivity values estimated by the model might be acceptable.

Keywords: GFLOW, model calibration, hydraulic conductivity, measurement scale, USA

Citation: Goswami D, P.K. Kalita, and E. Mehnert.  Estimation of watershed-scale hydraulic conductivity for two watershed sites using GFLOW.  Agric Eng Int: CIGR Journal, 2010, 12(2): 7-13.