ISSN:
1745-6584
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Energy, Environment Protection, Nuclear Power Engineering
,
Geosciences
Notes:
Delineating ground-water flow paths is difficult to accomplish in desert terranes because paucity of wells and boreholes yields little data to construct hydrologic interpretations based upon physical parameters. This is especially true in the Big Bend National Park where, in a study area encompassing over 500 km2, there are only four wells and six perennial springs. These wells and springs were sampled and analyzed for major-element chemistry as well as for stable and naturally occurring radioactive isotopes to identify sources of recharge for the springs which discharge along banks of arroyos incised in alluvial pediment lying about 900 meters below the uplands of the Chisos Mountains.The springs recharge could be from three sources: (1) infiltration of precipitation falling on the desert floor to discharge at nearby arroyos; (2) infiltration of water at the onlap of the alluvial fan with the crystalline rock of the Chisos uplands and subsequent flow within the fan toward lowland springs; and (3) upward migration of deep-seated water. Of these, the third scenario is least compatible with respect to temperature, dissolved oxygen, and isotopic data.The waters total dissolved solids and calcite saturation indices increase with decreasing altitude, suggesting recharge from the Chisos uplands. However, temperature, dissolved oxygen, δ18O, tritium, and Carbon-14 data indicate a significant recharge component to springs occurs by infiltration of infrequent precipitation falling on the arid alluvial lowlands. This water percolates through the soil zone to aquitards (essentially calcitic hardpans) which function as horizons which channel the water laterally toward discharge in springs. The springs recharge-to-discharge paths are short with flow being slow enough to reflect seasonal temperature differences of greater than 12°, yet recent enough to contain post-bomb spikes of tritium and Carbon-14.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1745-6584.1990.tb01711.x
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