Differences in dune morphology related to changes in groundwater geochemistry, White Sands National Monument
The White Sands of New Mexico contain transverse, barchan and parabolic dunes composed of gypsum sand. This study focuses on the zone of transition from barchan dunes that migrate rapidly (3 m/year) through an unvegetated landscape, to isolated parabolic dunes migrating at 1 m/year through vegetated, stabilized dunes and sand sheets (Mckee and Douglas, 1971). One theory is that the vegetated parabolic dunes can only form where enough sand has been deposited above the permanent saline water table to allow the formation of a fresh water lens. Conversely, where there is not enough vegetation, due to the proximity of the permanent and highly saline groundwater table, the sand blows away as barchan dunes, deflating the dune field. ^ A combination of geochemical sampling, ground penetrating radar and GPS surveying was used to test this theory. In a 5 km long swath through the dunes, 6 sites were established, two barchan, two parabolic and two in the transition zone. Groundwater and soil samples were collected in December 2004, and in March, May and June 2005 to measure both seasonal and spatial variations of water salinity. Groundwater and soil samples were analyzed for conductivity, total dissolved solids, dissolved oxygen and pH. The water table was less than 1.9 m deep, at all sites. (Abstract shortened by UMI.) ^
Rose, Jessica Mae, "Differences in dune morphology related to changes in groundwater geochemistry, White Sands National Monument" (2006). ETD Collection for University of Texas, El Paso. AAI1435320.