Case Study Analysis of Natural Resource Management in Western ColoradoEPA Grant Number: U914724
Title: Case Study Analysis of Natural Resource Management in Western Colorado
Investigators: Bradford, John H.
Institution: Rice University
EPA Project Officer: Broadway, Virginia
Project Period: January 1, 1995 through January 1, 1997
Project Amount: $68,000
RFA: STAR Graduate Fellowships (1995) Recipients Lists
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Earth Sciences
The objective of this research project is to develop an accurate description of the subsurface morphology of aquifers and confining units in a small island in the San Juan Archipelago.
Many of the San Juan Islands in the Puget Sound region of the Pacific Northwest depend on freshwater aquifers that lie in complex glacial-marine sedimentary environments. As the aquifers are depleted, sea water is drawn in, posing a serious salinization problem. A simple hydrogeologic model based on horizontally stratified layers is inadequate in this setting. To develop a useful model, it is essential that an accurate description of the subsurface morphology of the aquifers and confining units is developed. The sedimentary environment in which the aquifers lie poses a unique problem for direct imaging techniques such as high-resolution seismology. The complexity of the deposits is prohibitive of conventional data-processing techniques, and such techniques will not accurately represent the subsurface morphology. Yet, direct imaging techniques are necessary to provide the detailed information that is required.
The first stage of this research project will consist of developing seismic data acquisition and processing techniques, which will provide an accurate representation of the complex strata. To provide a control, seismic experiment data acquisition will be conducted parallel to cliffs that show good outcrop over 100 m of relief. Some uncertainty will be introduced by the horizontal offset required to avoid interference effects from the cliff face. Nonetheless, this provides an ideal setting to develop imaging techniques.
The second phase of this research project will consist of a detailed survey and interpretation of the primary aquifer system and overlying structure using primarily high resolution seismology. Potential field data will be collected to determine basement rock depth constraints, and a well will be drilled to provide calibration points. Ground-penetrating radar also may be used to obtain highly detailed information at very shallow depths (< 20 m). Additionally, a geodetic quality global positioning system will be used in lieu of conventional surveying procedures for station location in potential field analysis, geophone location, and appraisal of well head elevations.