To support calculation of flooding damages, better topographic data around river mouths were needed. Topographic contouring at 1 ft (0.3 m) intervals would allow the team to determine the area of inundation, and thus damages, for each 1 ft (0.3 m) rise in water level. With the existing digital orthophotos, the best contouring that could have been accomplished was 4 ft (1.2 m) contour intervals. This would have been inadequate to define the stage-damage curve in sufficient detail.

A process using Light Detection and Ranging (LIDAR) to measure terrain elevation was employed. The system uses a laser light, digital camera, GPS to measure aircraft position, and an inertial measurement unit to measure aircraft attitude. The combined system is used to collect high-accuracy terrain elevation data.

Examples of terrestrial LIDAR mapping are found below. The top image is an example from the Lake Macatawa area. The bottom example shows shaded topographic detail and the high water contour indicated in red.

Topo LIDAR work in the river mouth areas in the Michigan prototype counties was completed in 2000 and was performed with good success.

Click to return to the GIS Analyses Home Page.