Bathymetric and hydrodynamic surveys of Lake Michigan nearshore near Ogden Dunes/Burns Harbor, Indiana

The US Army Corps of Engineers (USACE) is evaluating the placement of dredged material in the nearshore areas of Lake Michigan as a means to replenish sand at selected beaches. In order to elucidate the physical processes in the nearshore environment that transport and distribute sand to the beach, the USACE-Chicago District and the US Geological Survey (USGS) developed a plan for a beach nourishment study on Lake Michigan near Burns Harbor/Ogden Dunes, Indiana. As part of this plan, the USGS conducted hydrodynamic and bathymetric surveys of the study area before and after placement of dredged material in the nearshore zone. The planned placement of dredge material in the study area occurred between June 15, 2016 and July 15, 2016. A second, unplanned placement of dredge material in the study area was observed on September 8, 2016. On June 2, 2016, the USGS deployed two upward-profiling acoustic Doppler current profilers (ADCPs) to the Burns Harbor/Ogden Dunes study area to collect wave/current data. Data was recovered from only one of these upward-profiling ADCPs. Additionally, a series of five bathymetric surveys with a boat-mounted ADCP, two topographic surveys with a Real Time Kinematic differential Global Positioning System (RTK-dGPS), and two bathymetric surveys with a Multibeam Echosounder (MBES) were completed in the study area between June 2016 and November 2016.

美国陆军工程兵团（US Army Corps of Engineers, USACE）正评估在密歇根湖近岸区域处置疏浚物的方案，以此为选定海滩补充沙源。为阐明近岸环境中泥沙输运并分布至海滩的物理过程，美国陆军工程兵团芝加哥分局与美国地质调查局（US Geological Survey, USGS）针对印第安纳州伯恩斯港/奥格登当斯附近的密歇根湖海滩养护研究制定了实施方案。作为该方案的组成部分，美国地质调查局在近岸区域投放疏浚物的前后，对研究区域开展了水动力与水深地形测量。计划中的疏浚物投放作业于2016年6月15日至7月15日期间在研究区域内完成。2016年9月8日，研究区域内观测到一起未计划的疏浚物投放事件。2016年6月2日，美国地质调查局在伯恩斯港/奥格登当斯研究区域部署了两台向上剖面型声学多普勒流速剖面仪（acoustic Doppler current profilers, ADCP）以采集波浪与海流数据，但仅成功回收其中一台设备的观测数据。此外，2016年6月至11月期间，研究区域内完成了五次采用船载声学多普勒流速剖面仪的水深地形测量、两次采用实时动态差分全球定位系统（Real Time Kinematic differential Global Positioning System, RTK-dGPS）的地形测量，以及两次采用多波束测深仪（Multibeam Echosounder, MBES）的水深测量。