HR: 17:45h
AN: H14A-08    [Abstracts]
TI: How good are hydraulic-conductivity data?
AU: * Hill, M C
EM: mchill@usgs.gov
AF: US Geological Survey, 3215 Marine St, Boulder, CO 80303 United States
AB: Mathematical theories gain utility in addressing ground-water problems by integration with site-specific data of all kinds. These data are always uncertain, and it is important to understand and quantify this uncertainty. Two studies conducted to evaluate hydraulic-conductivity data are reviewed and compared here. The first study involves a highly controlled intermediate-scale laboratory experiment constructed of clean sands with hydraulic conductivities that vary over about two orders of magnitude and are measured using permeameter and column experiments (Barth and others, 2001, WRR). The second study involves an extensively monitored field tracer test in fluvial deposits with hydraulic conductivities that vary over about 6 orders of magnitude and were measured using borehole flowmeters (Barlebo and others, 2004, WRR). In both studies, tracer tests were conducted and hydraulic heads measured. The hydraulic-conductivity measurements were evaluated by attempting to use them predictively in numerical flow and transport simulations of the systems. This resulted in predictions that matched the measured heads and concentrations more poorly than expected. The discrepancies are investigated by determining what hydraulic conductivities would be needed to reproduce the measured heads and concentrations, comparing these to the measured values, and considering whether the problem is the measured hydraulic conductivities or other aspects of the simulation. In the field problem, a system for evaluating the differences is proposed. Results suggest that this investigative approach can help understand errors in common types of data. Specifically, hydraulic-conductivity measurements are likely to be problematic enough that their use in ground-water model development needs to be considered carefully.
UR: http://wwwbrr.cr.usgs.gov/projects/GW_ModUncert/
DE: 1829 Groundwater hydrology
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting