Using LiDAR for River Engineering

From self-driving cars to 3D scanners, LiDAR technology can "see" its surroundings in incredible detail. Among the myriad uses, the high resolution data provided by LiDAR has beneficial engineering applications, specifically the creation of detailed hydraulic models. Here's how:

LiDAR for River Engineering

LiDAR or Light Detection and Ranging is a type of remote sensing that uses light in the form of pulsed lasers to measure distance. While the technology can be terrestrial, airborne, or mobile, the process remains the same. A laser emits a pulse that is read by a sensor to determine the difference in wavelength and return time to calculate distance. A GPS system is used to georeference the pulse for an accurate location in X, Y, Z space. Certain sensors can take over 100,000 measurements per second allowing the creation of dense, high resolution topography data.

airborne-lidar
 
Image Source: Fernandez-Diaz, J. C. (2011). Lifting the Canopy Veil - Airborne LiDAR for Archeology of Forested Areas. Imaging Notes, 26(2).

 

LiDAR is a particularly useful for river engineering because of the much higher data density compared to traditional survey methods. Accurate representation of complex river corridors and floodplains allows precise hydraulic modeling and analysis of these river systems. A significant additional benefit of LiDAR is the ability to see through vegetation. Analysis of a laser pulse’s different returns make it possible to infer the ground elevation even under dense tree canopies and vegetation.

Use the slider to view Aerial Imagery vs. LiDAR Topography.
Click here to view the image in greater detail. 

 

Presently, the use of LiDAR data for engineering projects is quite common as cities, counties, and even entire states have invested in acquiring LiDAR data to support a variety of studies. However, the use of LiDAR data is not confined to the realm of traditional engineering methods. Going one step further, this high resolution data can be used as a form of digital art. Personally, I consider a well-made map a form of art itself, and in my opinion, few can compare to the series of Mississippi meander maps created by Harold Fisk in 1944. Commissioned by the US Army Corps of Engineers, this series of 15 maps plot the different stages of channel evolution as the Mississippi River continues to evolve in its journey to the Gulf of Mexico. For this example, Plate 22 Sheet 7 was used as the base map. Then, the LiDAR topography was used to create highlights and shadow—simulating light shining on the terrain. The LiDAR data was then layered on top of the original map to add a level of detail that was not possible in 1944.

Use the slider to view The Original 1944 Map vs. LiDAR Enhanced Map.
Click here to view the image in greater detail. 
 

In Conclusion

LiDAR is a useful technology that has a variety of applications. Specifically within the realm of river engineering, the high resolution topography data is a useful input for detailed hydraulic models. Additionally, the information can be used for map making and creating digital art.

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