HR: 13:55h
AN: H22F-02 INVITED     [PDF]
TI: Visualizing and Analyzing Geologic and Hydrologic Models of the Death Valley Regional Ground-water Flow System, Nevada and California
AU: * Faunt, C C
EM: ccfaunt@usgs.gov
AF: U.S. Geological Survey, 5735 Kearny Villa Rd., Suite O, San Diego, CA 92123 United States
AU: San Juan, C
EM: csanjuan@usgs.gov
AF: U.S. Geological Survey, Denver Federal Center, P.O. Box 25046, MS 421, Denver, CO 80225 United States
AB: Numerical modeling of the Death Valley regional ground-water flow system, Nevada and California, involves the conceptualization and simulation of a complex and heterogeneous geologic and hydrologic system. The hydrogeologic characteristics of the region result from an arid climate and complex geology. Interbasin regional ground-water flow occurs through a thick Paleozoic carbonate-rock sequence, a locally thick Tertiary volcanic-rock sequence, and basin-fill alluvium. Throughout the system, deep and shallow ground-water flow may be controlled by extensive and pervasive faults and fractures. Understanding ground-water flow requires the formulation of conceptual and digital models that characterize the three-dimensional (3D) hydrogeologic framework within which the water moves. Part of this study includes the construction of a digital 3D geologic model that provides a description of the geometry and composition of the hydrogeologic units and structures that control ground-water flow. These hydrogeologic units and structures are then simulated in the hydrologic model using the Hydrogeologic Unit Flow (HUF) Package and the Horizontal-Flow Barrier (HFB) Package of the ground-water modeling code MODFLOW-2000. The HUF Package allows the geometry of the hydrogeologic units to be defined explicitly using hydrogeologic units that can be different from the defined flow-model layers. The HFB Package allows the simulation of features that retard flow. Likewise, zone and multiplication arrays can be utilized to incorporate hydraulic property detail, such as facies changes within a particular unit. Utilizing these capabilities significantly contributes to the ability of the modeler to better simulate the hydrogeologic conceptual model of the flow system. As geologic and hydrologic modeling software increase in complexity, modelers have the ability to better visualize and interact with the simulated hydrogeologic system and flow-model results. Post-processing utilities such as MODPATH and ZONEBUDGET allow the calculation of information helpful for analyzing the vast quantities of data. New and existing geographic information system (GIS) techniques can be used to visualize these results, such as flow paths and water-budget data, as well as water-level altitudes, hydrogeologic units, zone arrays, and flow-model layers. For example, three-dimensional views of particle paths along with the geometry of hydrogeologic units and structures provide insight into which features may be controlling ground-water flow paths. Employing GIS to develop maps of flux in and out of particular parts of the system aids in the visualization of the water budget. In addition, with the advent of the newer techniques and modeling tools the scientist can better explore the links between the hydrogeologic framework and the flow system. For instance, the scientist may conduct hypothesis testing regarding the hydraulic parameters associated with specific units or features based on visualizations analyses performed with the aid of GIS. Thus, the power of combining the GIS techniques and modeling packages is that, in addition to helping the scientist calibrate the ground-water model, it allows the scientist to test the degree to which the flow-model results match the conceptual model.
DE: 1829 Groundwater hydrology
DE: 3210 Modeling
SC: Hydrology [H]
MN: 2003 Fall Meeting