ADCP bathymetry 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. In support of this effort, five bathymetric surveys with a boat-mounted Teledyne RDI 1200 kHz acoustic Doppler current profiler (ADCP) were completed in the study area. ADCP data were collected using WinRiverII and exported for post-processing in The Velocity Mapping Toolbox (VMT) (Parsons et al., 2013). A tide file of water surface elevations for each transect in each survey was derived from the nearest USGS gaging station (Portage-Burns Waterway at Portage, IN; gage number 04095090; USGS National Water Information System, http://dx.doi.org/10.5066/F7P55KJN) and used to convert the ADCP-measured depths into bed elevations with the Export Multibeam Bathymetry tool in VMT. The surveys occurred on the following dates: June 2, 2016, July 20, 2016, September 8, 2016; October 11-12, 2016, and November 15, 2016. These survey dates bracket a planned placement of dredged material in the study area that occurred between June 15, 2016 and July15, 2016. In addition to the planned placement of dredge material, an independent dredging barge was observed working in the study area on Sept. 8, 2016. Parsons, D. R., Jackson, P. R., Czuba, J. A., Engel, F. L., Rhoads, B. L., Oberg, K. A., Best, J. L., Mueller, D. S., Johnson, K. K. and Riley, J. D. (2013), Velocity Mapping Toolbox (VMT): a processing and visualization suite for moving-vessel ADCP measurements. Earth Surf. Process. Landforms, 38: 1244–1260. doi: 10.1002/esp.3367

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投放疏浚物料的方案，以此为选定海滩补充沙源。为阐明近岸环境中驱动沙粒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区与美国地质调查局（US Geological Survey, USGS）联合制定了一项针对印第安纳州伯恩斯港/奥格登邓恩附近密歇根湖海滩养护研究的计划。
为支撑该项研究，科研团队在研究区域内完成了五次水深测量，所用设备为船载泰莱达因RDI 1200 kHz声学多普勒流速剖面仪（acoustic Doppler current profiler, ADCP）。ADCP数据通过WinRiverII软件采集，并导出至流速测绘工具箱（Velocity Mapping Toolbox, VMT）（Parsons等，2013）中开展后处理。
每次测量中各断面的水面高程潮汐数据文件均取自最近的USGS水文测站——印第安纳州波蒂奇的波蒂奇-伯恩斯水道站（测站编号04095090；USGS国家水信息系统，http://dx.doi.org/10.5066/F7P55KJN），并通过VMT中的多波束水深导出工具，将ADCP测得的水深转换为床面高程。
本次五次测量的日期分别为：2016年6月2日、2016年7月20日、2016年9月8日、2016年10月11日至12日，以及2016年11月15日。上述测量时段覆盖了计划于2016年6月15日至7月15日之间在研究区域开展的疏浚物料投放作业。除本次计划内的疏浚物料投放外，2016年9月8日观测到一艘独立运营的疏浚驳船在研究区域内作业。
参考文献：Parsons, D. R., Jackson, P. R., Czuba, J. A., Engel, F. L., Rhoads, B. L., Oberg, K. A., Best, J. L., Mueller, D. S., Johnson, K. K. 及 Riley, J. D. (2013)，《流速测绘工具箱（VMT）：船载ADCP测量的处理与可视化套件》，《地球表面过程与地形》（Earth Surf. Process. Landforms），38卷：1244–1260。doi: 10.1002/esp.3367