Combining Multiple Seismic and Ground Penetrating Radar Techniques to Analyze Geologic Controls of Riparian Meadow Complexes in the Central Great Basin, Nevada USA
G.S. Baker and K. Sturtevant
Event name: Near Surface 2007 - 13th EAGE European Meeting of Environmental and Engineering Geophysics
Session: Best of SAGEEP
Publication date: 03 September 2007
Info: Extended abstract, PDF ( 4.55Mb )
Price: € 20
Riparian meadow systems in the Central Great Basin are of interest because they support the majority of ecosystem diversity in the region. The riparian meadows are highly dependent upon groundwater levels, thereby making them vulnerable to fluctuations. These systems are actively degrading due to incision of the streams, resulting in a lowered water table and modification of the associated ecosystems. Geologic controls, such as bedrock geometry and sediment variability, are important in the meadows because of their control on the overall system. The current hypothesis is that the sediments associated with side-valley alluvial fans and fault-related bedrock steps interact to constrict ground water flow. Seismic reflection data and seismic refraction tomography data were collected to analyze bedrock structure and topography from 10 to 80 meters depth, while ground penetrating radar (GPR) data were collected to determine the stratigraphic variability in the upper 10 meters. These data were integrated to provide a comprehensive interpretation of the upper 80 meters of the subsurface. Seismic reflection data were processed to identify the bedrock surface. This surface was then correlated with the seismic refraction tomography to extend the bedrock surface across the meadow complexes. The large volume of GPR data were interpreted by classifying radar facies based on the characteristics of the radar reflectors. These facies (in conjunction with borehole information) confirm and extend areas of alluvial fan related sediment distribution. Integration of these three geophysical techniques is advantageous because they provide more information than could be obtained with the individual techniques.