THE USE OF LIDAR IN MONITORING MORPHOLOGIC CHANGE AT FIRE ISLAND NATIONAL SEASHORE

The U.S. Geological Survey (USGS) and the National Park Service (NPS) have collaborated to use the Experimental Advanced Airborne Research Lidar (EAARL) to collect data for ecological monitoring, storm-event assessment, habitat mapping, and evaluating geomorphic change. In this study, 1-m digital elevation models (DEMs) were created from EAARL point data to assess and monitor morphologic change. The analyses took place along the Fire Island National Seashore, a 41.8-km long stretch of the Fire Island barrier island located on the south shore of Long Island, New York. Multiple, repeat surveys designed for the conservation and monitoring of critical coastal habitat have been conducted over the study area as part of the NPS Inventory and Monitoring (I&M) Program. The data collection periods for the Fire Island study site occurred in fall 2002, spring 2005, spring 2007, summer 2009, and fall 2009. Lidar data was collected on these dates to capture impacts from storms and major anthropogenic modifications that occurred during the time period. Morphologic change was calculated between each of the acquisition periods by calculating net volumetric change per unit area (m). The study area exhibited short-term morphologic change along the beach that are affected by the variability of sediment sources and sinks, episodic storms, and anthropogenic modification. Results from the study site show that the beaches are erosional or depositional over a range of temporal and spatial scales.