CHARACTERIZATION OF SPATIAL VARIABILITY OF HYDROGEOLOGIC PROPERTIES FOR UNSATURATED FLOW IN THE FRACTURED ROCKS AT YUCCA MOUNTAIN, NEVADA

摘要

In the conceptual model currently used for the site characterization of Yucca Mountain, the lateral variability of hydrogeologic properties and its effect on flow and transport is neglected by assuming uniform layer-scale properties at each hydrogeologic layer. In this research, the lateral variability of three most sensitive layer-scale hydrologic properties (matrix permeability κ_m, and matrix α_m, and fracture permeability κ_f,) was investigated using individual inverse modeling. The calibration of the three properties at each deep borehole was performed using measurements of water saturation, water potential and pneumatic pressure, and those of intrinsic permeability and desaturation curve data. All other hydrologic properties are fixed at their optimal laterally averaged values obtained by simultaneous inverse modeling. Considerable lateral variability of hydrogeologic properties is obtained. The lateral variability of κ_m is two to three orders of magnitude and that of α_m and κ_f is one order of magnitude. The lateral variability of κ_m is smaller than the dominant vertical variability of five to six orders of magnitude between hydrostratigra-phic units.