Mapping Near-Surface Salinization Using Long-Wavelength AIRSAR
Jeffrey G. Paine, principal investigator

In this multiyear study, which ended in July 2002, we explored whether long-wavelength airborne radar (AIRSAR) data can be used to cost-effectively survey large areas for evidence of salinization of near-surface soil and water. Because radar waves are sensitive to the electrical properties of the ground, and because the electrical conductivity of soil and water greatly increases with salinity, we attempted to use airborne radar as a screening tool to identify salinization. We expected radar reflectance to be influenced by ground conductivity (particularly at the longer wavelengths) and expected some degree of correlation between radar reflectance images at these wavelengths with ground conductivity images recorded during our previous studies of these test areas. In support of this study, the National Aeronautics and Space Administration (NASA) collected and processed AIRSAR data in two test areas: (1) within the Colorado River watershed near San Angelo in West Texas, where a 1996 airborne EM survey revealed the presence of natural, oilfield-related, and agricultural salinity sources, and (2) within the Red River basin of Texas and Oklahoma, where a 1997 airborne geophysical study of salt-impacted agricultural lands revealed oilfield-related salinization extending over many square kilometers. Comparisons of radar reflectance images with aerial photographs and detailed ground conductivity maps revealed that AIRSAR can reliably identify areas where salinization has resulted in loss of vegetation but cannot delineate larger areas of subsurface salinization that have not significantly affected surface vegetation.

For more infomation, please contact Jeff Paine, principal investigator. Telephone 512-471-1260;
February 2003