Coastal LiDAR and Rapid Detection of Changes after Hurricanes
The Joint Airborne Lidar Bathymetry Technical Center of Expertise (JALBTCX) has developed a state-of-the-art capability to collect post-hurricane lidar data and to deliver maps and quantities of change in elevation, shoreline position, and beach volume caused by storms, all on time scales relevant to the emergency response community. JALBTCX is an interagency partnership among the U.S. Army Corps of Engineers (USACE), Naval Oceanographic Office (NAVOCEANO), National Oceanic and Atmospheric Administration (NOAA), and U.S. Geological Survey (USGS) in operations, research, and development in airborne lidar bathymetry and complementary airborne coastal mapping and charting technologies. USACE deployed JALBTCX to collect data to quantify the regional impacts of storms after the hurricane seasons of 2004 (Charley, Frances, Ivan, Jeanne), 2005 (Dennis, Katrina), 2006 (Wilma), and 2009 (Gustave, Ike). However, the first requirement for rapid collection and delivery of data (within days) along with elevation, shoreline, and volume change analyses came in 2012 in the aftermath of Hurricane Sandy. JALBTCX identified a number of operational, processing, analysis and delivery challenges during execution of the post-Sandy work. JALBTCX evolved operations, processing, delivery and communications to address these challenges, and had an opportunity to test them in the aftermaths of Hurricanes Matthew (2016) and Irma (2017). Final, classified bathy-topo lidar, along with first-return and bare earth DEMs, shorelines, and metadata, were delivered within a week of collection. Web services were developed to communicate progress in data collection, processing, change analyses, and delivery, and delivery of pdf map products. JALBTCX implemented PP-RTX, eliminating the need for surveyors in the hurricane impact area of survey, but still maintaining required data accuracies (10 cm RMSE topography, 15 cm one standard deviation bathymetry). Aerial photography, lidar DEMs, and elevation change maps were all delivered using web services. Processing of shoreline and volume change products was improved so that regional analyses were delivered incrementally through web services as post-storm data became available. Challenges that remain are schedule and consistency of pre-event data. Normal operations allow operators to choose best conditions for survey, but emergency operations force data collection in non-optimal conditions that cause more intensive manual processing and editing. Despite common standards, classification of lidar data and development of DEM deliverables are inconsistent among providers and can cause artifacts in change detection products that invalidate the results and often require rework of data. This presentation will briefly describe the evolution and current state-of-the-art of JALBTCX emergency coastal lidar mapping capability, products, and delivery mechanisms. Remaining challenges and proposed solutions will be presented, along with other opportunities for lidar data to meet emergency response requirements, but for which standardized workflows have yet to be developed.