Variations in subsidence along the Gulf of Mexico passive margin determined from Airborne-LiDAR data in Louisiana and Texas

The Gulf of Mexico is affected by sea-level rise and subsidence at different spatial and temporal scales. On a global scale, the sea level is expected to rise 65 12 centimeters by 2100 mainly affecting coastal areas. Subsidence rates vary along the Gulf of Mexico passive margin, owing to factors such as variable compaction of sediments, extraction and injection of fluids, glacial isostatic adjustment, and slip along growth faults. It is crucial to coastal communities to know how subsidence varies across the region and its relationship with wells and faults. Our objective is to quantify subsidence rates and horizontal movement using airborne LiDAR in two areas in the Gulf of Mexico; East Baton Rouge - LA, and Jefferson County TX, both of which are affected by faulting and the extractive industries. Our work tests the functionality of this type of data detecting changes at millimetric scales and compares results with InSAR measurements. The point clouds for the area in Louisiana were captured in 1999 and 2018 and have a point space of 4 meters and 0.33 meters, respectively. For the area in coastal Texas, the point clouds were captured in 2006 and 2017 and have a point space of 1 meter and 0.33 meters, respectively. To quantify subsidence, we are performing LiDAR differencing using two approaches: Iterative closest point algorithm (ICP) and vertical differencing using the Geomorphic Change Detection (GCD) software. The ICP approach allows us to estimate horizontal and vertical displacement using the LiDAR points clouds directly and perform horizontal co-registration. Using the co-registered information, we perform vertical differencing of digital elevation models from the LiDAR point clouds to calculate vertical displacement. Finally, we compare the results from both methods and results from InSAR information from the satellites ENVISAT and Sentinel-1.