HR: 0800h
AN: H11C-0314 INVITED     [Abstracts]
TI: The Relative Importance of Concentration and Mass Flow Observations in the Calibration of Solute Transport Simulations
AU: * Yager, R M
EM: ryager@usgs.gov
AF: U.S. Geological Survey, 30 Brown Rd, Ithaca, NY 14850 United States
AB: Model calibration of ground-water flow simulations through parameter estimation has indicated that observations of flow are highly influential in the estimation of hydraulic properties. Moreover, estimates of some pairs of properties, such as hydraulic conductivity and recharge, are highly correlated when only observations of hydraulic head are specified. As a result, additional information, such as flow measurements, is required to independently estimate values for these two parameters. In contrast, little information has been published concerning the relative influence of different types of observations used to calibrate solute transport simulations. The solute transport simulation in this work utilized BIOMOC to represent biodegradation of trichloroethene (TCE) and UCODE to apply nonlinear regression to estimate reaction rates. The simulation was calibrated to concentrations of TCE and its metabolites (1,2-cis-dichloroethene, vinyl chlorine and chloride) measured under natural gradient and pumping conditions, and the pumped mass of chlorinated ethenes during a five-year period. The transport simulation required the specification of a boundary condition and associated parameter to represent the source of TCE and four other parameters: the effective porosity of the aquifer material and three first order rate constants governing the sequential biodegradation of TCE to ethene. These parameters were correlated and could not be estimated independently with the available data. The assumptions and additional information, such as ground-water velocity, required to uniquely estimate all these values will be discussed. The relative influence of observations of concentration and mass flow computed using the influence statistics Cook's D and DFBETAS will be compared and discussed in relation to their value in reducing parameter correlation.
DE: 1829 Groundwater hydrology
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting