DETERMINING ANNUAL TO DECADAL SUBSIDENCE RATES AND AREAS USING AIRBORNE LIDAR, GPS, AND TOPOGRAPHIC MAPS AT THE WINK SINKHOLES, WEST TEXAS

Data from repeat airborne lidar topographic surveys, differential GPS surveys, satellite radar interferometry, and older topographic maps suggest that rapid land subsidence has been occurring for many years near two large (100- to 200-m diameter) sinkholes that formed in 1980 and 2002 in the Hendrick Oil Field near Wink, Texas. The sinkholes and surrounding subsiding area overlie Permian bedded evaporite strata on the Central Basin Platform on the eastern margin of the Delaware Basin. Previous investigations using interferograms constructed from synthetic aperture radar data acquired between 2008 and 2011 with the ALOS PALSAR L-band satellite-borne instrument identified local areas that were subsiding at rates reaching a few cm per month. These results focused ground-based microgravity surveys on areas where subsidence is occurring to identify where shallow mass deficits exist that would increase the likelihood of future subsidence or collapse. We have also quantified ongoing and longer-term elevation change by comparing (1) digital elevation models (DEMs) constructed from high-resolution airborne lidar data acquired in 2013 with lower-resolution DEMs constructed from USGS photogrammetry-derived elevations from the 1960s, (2) differential GPS measurements acquired during microgravity surveying in 2015 with 2013 lidar-derived elevations, and (3) elevations determined from a second airborne lidar survey in 2017 with those determined from the 2013 lidar survey. These comparisons reveal that total subsidence reaches more than 10 m over 45 years in some areas. Maximum net rates of subsidence measured on the decadal time scale are about 0.25 m/yr. Differential GPS-derived elevations measured in 2015 were as much as 1 m lower than 2013 lidar-derived elevations, yielding maximum subsidence rates of nearly 0.5 m/yr. Elevation loss between the 2013 and 2017 airborne lidar surveys are as great as 2.5 m over four years, yielding net rates as high as 0.6 m per year. These recent rates are similar to those determined from radar interferometry and are higher than the maximum decadal-scale rates.