Marine Corps Base Camp Lejeune Onslow Bay Bathymetry

Critical military training and testing on lands along the nation’s coastal and estuarine shorelines are increasingly placed at risk because of development pressures in surrounding areas, impairments due to other anthropogenic disturbances, and increasing requirements for compliance with environmental regulations. The U.S. Department of Defense (DoD) intends to enhance and sustain its training and testing assets and to optimize its stewardship of natural resources through the development and application of an ecosystem-based management approach on DoD installations. To accomplish this goal, particularly for installations in estuarine/coastal environments, the Strategic Environmental Research and Development Program (SERDP) launched the Defense Coastal/Estuarine Research Program (DCERP) as a minimum 10-year effort at Marine Corps Base Camp Lejeune (MCBCL) in North Carolina. The results of the first six years of the program (DCERP1) are presented here. The overarching objectives of DCERP are to: (1) understand the effects of military training activities, infrastructure development, and other coastal military installations; (2) develop models, tools, and indicators to evaluate ecosystem health; and (3) recommend adaptive management strategies to sustain ecosystem natural resources within the context of an active military installation. Bathymetry data are from the shallow (-2 to -11.5m, NAVD88) region of Onslow Bay, adjacent to Onslow Beach, NC. Data were collected in 2007 using a high-resolution (234 kHz) Sea Swath Plus Interferometric swath bathymetric profiler with co-registered side-scan sonar. Line spacing ranged from 50-150m to allow for nearly complete coverage of the seafloor, minimizing data holidays. The position of each data point was related to NAD83 using RTK-GPS. Vessel heave, pitch, and roll were corrected in real-time using an IXSEA Octans motion sensor. Seafloor depths were corrected to NAVD88 using Hypack software. Data were initially processed and gridded using proprietary software at a 2-m resolution, and were despiked, filtered, and smoothed. For purposes of nearshore-wide bathymetric mapping, the data were later gridded using Fledermaus IVS 7.0.1 Pro using a weighted moving average at a resolution of 5m7wt. Data span the nearshore off of Onslow Beach as well as the portions of New River Inlet.