HR: 1340h
AN: H13A-1331    [Abstracts]
TI: Parameter Sensitivity Analyses For A Large-Scale Unsaturated Flow Model
AU: * Zhang, K
EM: kzhang@lbl.gov
AF: Erath Sciences Division, Lawrence Berkeley National Laboratory, MS 90-1116, 1 Cyclotron Rd, Berkeley, CA 94720 United States
AU: Wu, Y
EM: YSWu@lbl.gov
AF: Erath Sciences Division, Lawrence Berkeley National Laboratory, MS 90-1116, 1 Cyclotron Rd, Berkeley, CA 94720 United States
AU: Houseworth, J
EM: JEHouseworth@lbl.gov
AF: Erath Sciences Division, Lawrence Berkeley National Laboratory, MS 90-1116, 1 Cyclotron Rd, Berkeley, CA 94720 United States
AB: Field investigations for the Yucca Mountain site have shown that large variabilities exist in flow parameters over the spatial domain of the mountain. Even though considerable progress has been made in model development for this area, uncertainty associated with the site-scale unsaturated zone (UZ) flow model input parameters has not been investigated in depth. In this study, parameter sensitivity analyses have been conducted using the site-scale 3-D UZ flow model. The sensitivity analyses are intended to evaluate the effects of uncertainties in hydrologic parameters on UZ flow and contaminant transport. Sensitivity analyses are carried out using the parameter uncertainties for fracture and matrix permeabilities and van Genuchten alphas, which are the most sensitive parameters affecting UZ flow simulations. These sensitivity simulations are performed using the UZ flow model by incrementing or decrementing a given parameter by one standard deviation, a modification performed for each parameter in all the hydrogeologic units/layers as well as faults. The parameter variation results in a total of eight parameter sets to account for the uncertainties of the four hydrological parameters. Modeling results for the eight flow simulation sensitivity cases have been compared with observed borehole matrix liquid saturation, matrix water potential, and perched water data. In addition, the eight simulations are also compared with simulation results from the base-case parameter set. The effects of parameter uncertainties on the flow fields are discussed in detail through the comparison of results.
DE: 1805 Computational hydrology
DE: 1829 Groundwater hydrology
DE: 1873 Uncertainty assessment (3275)
DE: 1875 Vadose zone
SC: Hydrology [H]
MN: Fall Meeting 2005