HR: 1340h
AN: H23A-1110    [Abstracts]
TI: Hydrostratigraphic Characterization Using High-resolution Borehole Moisture Logs and Grain-size Distribution Statistics
AU: * Ward, A L
EM: andy.ward@pnl.gov
AF: Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 United States
AU: Keller, J M
EM: jason.keller@pnl.gov
AF: Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 United States
AU: Zhang, Z F
EM: fred.zhang@pnl.gov
AF: Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 United States
AU: Gee, G W
EM: glendon.gee@pnl.gov
AF: Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352 United States
AB: Small-scale heterogeneities typical of natural soils are known to impact field scale flow. Model predictions of flow and transport under such extreme variations in hydraulic and geochemical properties often show large discrepancies from field observations, perhaps because small-scale variations are often ignored. In this study, we develop pedotransfer functions, based entirely on the statistics of the particle-size distribution, to predict hydraulic and geochemical properties at multiple scales. Grain-size statistics, namely mean diameter, d$_{g}$, sorting index, S$_{o}$, and the Fredle index, F$_{i}$, are derived from samples taken on a coarse sampling interval. A relationship between the size-statistics and specific retention is coupled with high-resolution neutron moisture logs to predict size statistics on intervals as small as 3 inches. Hydraulic and geochemical properties, reflecting the small-scale heterogeneity, are then generated using the pedotransfer functions. Flow and transport of reactive contaminants using the STOMP simulator show very good agreement with observations from a waste site at Hanford. Hydrostratigraphic models ignoring the small scale heterogeneity were unable to match field observations. The Pacific Northwest National Laboratory is operated for the U.S. Department of Energy by Battelle under Contract DE-AC06-76RL01830.
DE: 1866 Soil moisture
DE: 1875 Unsaturated zone
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting