Bathymetric LIDAR (SHOALS) Data

High density bathymetric data for select areas along the Lake Michigan coastline were collected in late 1999. Data were collected using the Scanning Hydrographic Operational Airborne Lidar Survey (SHOALS) system. The SHOALS system was developed for the U.S. Army Corps of Engineers. The SHOALS system is based on light detection and ranging (LIDAR) technology. A laser signal is beamed from a helicopter or plane. Multiple receivers are in place to detect water surface hits and bottom hits. The depth of water is determined based on the time difference between the water surface beam return and the bottom beam return, accounting for light propagation through the water and waves.

Processing of the SHOALS data was completed in early 2000 and was used in the coastal modeling process. Due to poor weather conditions prior to the SHOALS survey, complete coverage in the targeted areas was not achieved. High turbidity in the harbor entrance areas and in nearshore areas prevented the light beam from penetrating to obtain a bottom depth reading. The areas with no bathymetric data in the counties surveyed will be re-surveyed with the SHOALS system in the Summer of 2001. There are several areas, particularly around harbor entrances, that are routinely turbid and cannot be surveyed with SHOALS. These areas will be surveyed with conventional hydrographic survey techniques in the Spring of 2001. The Figure above illustrates the bathymetric contours generated using the SHOALS data.

Integrated Bathymetric Data (NOAA) - River Mouth Areas

Detailed bathymetric data for the rivermouth and harbor areas was necessary to assess potential low water impacts to shoreline structures, docks, and marinas. Because a detailed hydrographic survey for each harbor was impractical, the data from NOAA navigation charts were used to develop 1ft (0.3 m) contours of the bathymetry in Lake Macatawa, Saugatuck Harbor/Kalamazoo Lake, Grand River/Spring Lake, and Sheboygan Harbor. Due to the nature of the methodology, the bathymetric contouring is approximate, but provides sufficient detail for the purposes of this study. The figures below illustrate the bathymetry for a portion of Lake Macatawa. The left figure uses shaded bathymetric polygons, the right, contours. the high water mark is indicated in red.

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