Vexcel Corporation has announced a three-year contract with the Arizona Department of Water Resources (ADWR) and the Center for Space Research, UT-Austin, to provide a system that will monitor ground elevation changes that occur as a result of groundwater extraction. Vexcel’s approach uses synthetic aperture radar data from satellites and differential interferometry (DIFSAR) technology to address the needs of ADWR and those of the broader water resource community. The program originates from NASA’s Earth Science Office.
Groundwater extraction, especially in areas of growing population, can produce ground sinking, or subsidence, when water extraction exceeds aquifer recharge rates. Potential impacts of the ground deformation include damage to buildings, roads and underground pipes. According to the National Research Council, the price tag for flooding and structural damage associated with subsidence exceeded $125M per year as of the early 1990s.
Vexcel, an international provider of advanced SAR processing systems and GIS services, will implement DIFSAR technology to operationally monitor Arizona’s subsidence. The operational system will include retrieving data from satellite radar sensors; evaluating and processing the data; and interpreting, formatting and presenting calibrated subsidence information to maximize utility to the user. The resulting calibrated subsidence maps will provide ADWR with the information necessary to develop policies and regulations that may mitigate subsidence and its hazardous effects.
Historically, regional subsidence monitoring has been expensive and limited but the development of DIFSAR technology is overcoming those drawbacks. In contrast, the comparable operational DIFSAR product may cost only a few thousand dollars.
Through Interferometric technology, DIFSAR uses synthetic aperture radar data from satellites to provide sensitive measurement of ground motion. Interferometry enables the collection of measurements of ground displacement by comparing electromagnetic signals collected at two different times.
Vexcel is currently developing a refinement of DIFSAR that utilizes Coherent Target Monitoring (CTM). As an emerging technology that mitigates difficulties resulting from interference by vegetation and water atmospheric vapor, CTM will make the application even more robust.
NASA is funding the ADWR project as part of its goal to extend space technology to commercial applications. Ultimately, Vexcel will offer this operational subsidence monitoring capability as a service to the U.S. water resource community.