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Levee Repair - LiDAR Topographic Surveys

DWR Levee Repairs Program
Department of Water Resources

3310 El Camino Avenue,
Suite 140
Sacramento, CA 95821

Mailing Address:
P. O. Box 219000
Sacramento, CA 95821-9000

For public comments or questions e-mail:

leveerepair@water.ca.gov

A helicopter equipped with a LiDAR system called FLI-MAP´┐Ż (Fast Laser Imaging - Mapping Airborne Platform) was used to conduct high-resolution surveys, still pictures, and a video record of the levee system. In the spring of 2007, a series of low-level helicopter flights was conducted over levees stretching from Oroville to Lathrop. These flights performed aerial topographic surveys using Light Detection and Ranging (LiDAR) technology, which electronically gathers surface data to help determine the topography and configuration of the flood control levees.

The flights covered more than 300 miles of urban levees, as well as 150 miles of other non-project-related levees (in an effort to assist local agencies and reclamation districts). The survey helicopter flew at approximately 500 feet over the levees with airborne equipment including a global positioning system (GPS), laser scanner, and digital cameras.

Survey images provide an accurate profile of the surface of the levees. Airborne surveys are generally non-invasive, and various types of data can be collected more rapidly compared to ground-based methods (e.g., drilling or boring). Airborne LiDAR systems can produce extremely accurate elevation models for terrain (even measuring ground elevation through trees), while offering a quick and efficient method of surveying terrain that is not easily accessible.

LiDAR, like the similar radar technology (which uses radio waves instead of light), determines the range to an object by measuring the time delay between transmission of a pulse and detection of the reflected signal.

The data collected is primarily used to obtain topographical information (via a digital terrain model), which assists in the evaluation of the geotechnical and erosion characteristics of the surveyed levees. This information may also be used in the future for vegetation and design purposes.