RAMSEY, Michael S., Geology Department, Arizona State University, Box 871404, Tempe, AZ 85287, ramsey@elwood.la.asu.edu; and LANCASTER, Nicholas, Desert Research Institute, 7010 Dandini Blvd., Reno, NV 89512.

Using remote sensing to study dynamic features such as dunes has given the geologist a synoptic view of entire eolian systems. The ability to examine changes over time also allows for the monitoring of marginal drought-prone regions susceptible to future desertification. As human activity increases, these areas can benefit from repetitive monitoring on the multi-year time scale. Such an observation strategy is currently being developed for the spaceborne Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER) instrument scheduled for launch in 1999. ASTER is part of NASA's new Earth observation satellites designed for long-term environmental monitoring. It will provide multi-spectral data from visible to the thermal infrared region at three different spatial scales. The primary mission is to compile a global map of the land surface, however resources have been allocated for focused scientific studies requiring more frequent data coverage. The arid lands monitoring project is designed to map desert regions and intensively observe certain key sites, chosen because of ongoing active research into the processes of land degradation and sand encroachment.

Prior to the proposal of such a monitoring effort, field sites in the Mojave Desert, CA were chosen and airborne data collected. These data were analyzed with newly developed deconvolution software using a spectral mineral library. At the Kelso Dune site, surface mineral maps derived from the data show sediment mixing patterns and confirm the possibility of performing similar studies from space. The Kelso dune are located at the terminus of a moderate-length sand transport path beginning 50 km to the west. Previous investigations have reported a fairly uniform mineralogy. However, processing of 1995 airborne data showed significant mineralogic differences, which were later confirmed by petrographic analysis. The data were deconvolved using a mineral library approach for endmember mineral selection. This technique produced mineral maps showing variations within the dunes, and identified a significant input source of potassium feldspar from a nearby granite-dominated alluvial fan. Using a similar approach, geologic mapping and monitoring of the global deserts will be possible with ASTER.

Key words: remote sensing, arid lands, desertification

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Presented at: Geological Society of America Annual Meeting
Date: 1998