Impacts of the Deepwater Horizon (DWH) oilspill on Gulf Coast marshes were documented using polarimetric synthetic aperture radar (PolSAR) collected by NASA’s Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) aircraft (http://dx.doi.org/10.1016/j.marpolbul.2014.10.032). Ground, optical, and PolSAR data were used to map heavy shoreline oiling; however, only PolSAR mapping identified an expansive area of interior marsh that showed dramatic change from pre-spill conditions in 2009 to post-spill conditions in 2010. No oil intrusion into the interior marshes was detected during the event, which occurred in 2010. To determine whether the PolSAR change in interior marshes might be related to the DWH oil spill, sediment samples were collected along shorelines and within interior marshes in 2011, one year after the DWH spill. Analytical chemists at Louisiana State University and USGS and NASA remote sensing analysts together determined that DWH oil extended beyond shorelines, suggesting that the oil spill could have affected much more of the southeastern Louisiana marshland than was concluded from ground and optical surveys. Although a causal relationship cannot be proven in interior marshes, results also verified a spatial association between PolSAR change and oil occurrence. The UAVSAR system, with on-demand response, high spatial resolution, high repeat targeting, and high canopy penetration capability, was demonstrated to be a possible prototype for an oil mapping system.
Top: Study area location and oil-contaminated mud. Left: (a) 2009 and (b) 2010 PolSAR processed scenes of the Mississippi River Delta marshes (http://dx.doi.org/10.3390/rs3122630). Changes in color denote changes in marsh condition. Right: (a) shoreline and (c) subcanopy DWH oiling. (b& d) Chemical fingerprinting showed sediment one year after spill contained DWH oil at these sites. The black outlines in b and d represent the pure DWH oil fingerprint, and the gray fill represents the site oil fingerprint. The closer the gray shading is to the black outline, the more likely the fingerprint is DWH oil.