Mountain Lake in Giles County, Virginia, has a documented history of severe natural lake-level changes involving groundwater seepage [Jansons, 2004] that extend over the past 4200 years [Cawley, 1999], and as of December 2010 the lake was about 2% full by volume. Situated in the Valley and Ridge physiographic province on the axis of a plunging anticline and straddling contacts between three upper Ordovician and lower Silurian formations, the lake is one of two natural lakes in Virginia.
A daily water balance, geophysical surveying with dipole-dipole electrical resistivity, and chemical sampling have shed light on the nature of flow to and from the lake, including: 1) the steady nature of net groundwater outflow, 2) the seasonal response to precipitation of a forested first-order drainage system in fractured rock, 3) the influence of a fault not previously discussed in literature regarding the lake, and 4) the possibility of flow pathways through karst features.
Results from a water balance indicate steady lake drainage and significant recharge when vegetation is dormant, particularly during rain-on-snow melt events. The resistivity profiles display a highly heterogeneous subsurface and reveal low-resistivity areas that suggest flow pathways to and from the lake. Well logs, satellite images, and outcrop observations appear to confirm the presence of a fault to the east of the lake. Chemical evidence suggests that karst features may be present in the upper Reedsville-Trenton formation underlying the lakebed. / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/31950 |
| Date | 09 May 2011 |
| Creators | Roningen, Jeanne Marie |
| Contributors | Geosciences, Burbey, Thomas J., Henika, William S., Mauldon, Matthew, Parker, Bruce C. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | Roningen_JM_T_2011_Copyright.pdf, Roningen_JM_T_2011.pdf |
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