Accession Number : ADA318655

Title :   Calibration of MADE-2 Groundwater Flow and Contaminant Transport Models,

Descriptive Note : Final rept. 1 Mar 94-31 Dec 95,

Corporate Author : WEST VIRGINIA UNIV MORGANTOWN

Personal Author(s) : Rucker, Dale F. ; Gray, Donald D.

PDF Url : ADA318655

Report Date : NOV 1996

Pagination or Media Count : 213

Abstract : Public domain computer programs were used to simulate groundwater flow and contaminant migration through a site at the Columbus Air Force Base Mississippi In the MADE-2 (Macrodispersion Experiment a pulse of dissolved contaminants in the saturated zone of an alluvial aquifer was monitored for 15 months. MODFLOW solved for head and seepage velocity for input to the transport code,MT3D. The contaminant transport equation was solved separately from the flow equation since buoyancy effects were assumed to be negligible. Initial simulations of the tritlum plume did not extend far enough from the injection site. An ad hoc assumption of horizontal anisotropy applied to the conductivity field produced good agreement with the observed plumes. Although the simulated plumes were realistic, the horizontally anisotropic conductivity field used to achieve these predictions was not. The principal axes were not aligned with the directions suggested by pump tests or geology, the anisotropy ratio was in excess of any previously observed, and the effective conductivity was above what had been measured at the site. The use of public domain software to model contaminant transport at heterogeneous sites is technically practical; but in the absence of exhaustive field measurements, little confidence can be placed in the predictions.

Descriptors :   *COMPUTER PROGRAMS, *WATER FLOW, *GROUND WATER, *WATER POLLUTION, *CONTAMINANTS, *CALIBRATION, TEST AND EVALUATION, MATHEMATICAL MODELS, SIMULATION, MEASUREMENT, RATIOS, CONDUCTIVITY, SITES, FIELD TESTS, GEOLOGY, SATURATION, CODING, TRANSPORT PROPERTIES, AQUIFERS, PULSES, ANISOTROPY, TRANSPORT, HETEROGENEITY, AIR FORCE FACILITIES, PLUMES, EQUATIONS, PUMPS, CONFIDENCE LEVEL, DISSOLVING, BUOYANCY.

Subject Categories : Hydrology, Limnology and Potamology
      Computer Programming and Software
      Water Pollution and Control

Distribution Statement : APPROVED FOR PUBLIC RELEASE