Measuring bluff erosion part 1: terrestrial laser scanning methods for change detection

ABSTRACT Human activities influence watershed sediment dynamics in profound ways, often resulting in excessive loading of suspended sediment to rivers. One of the primary factors limiting our ability to effectively manage sediment at the watershed scale has been our inability to adequately measure r...

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Bibliographic Details
Published in:Earth surface processes and landforms 2013-08, Vol.38 (10), p.1055-1067
Main Authors: Day, Stephanie S., Gran, Karen B., Belmont, Patrick, Wawrzyniec, Tim
Format: Article
Language:English
Subjects:
Bgi / Prodig
Cartography, space figuration
Change detection
Curvature
erosion
Erosion rate
Freshwater
Image interpreation. Remote sensing
Landforms
LiDAR
Mathematical analysis
remote sensing
River banks
Sediments
terrestrial laser scanning
Watersheds
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Summary:ABSTRACT Human activities influence watershed sediment dynamics in profound ways, often resulting in excessive loading of suspended sediment to rivers. One of the primary factors limiting our ability to effectively manage sediment at the watershed scale has been our inability to adequately measure relatively small erosion rates (on the order of millimeters to centimeters per year) over annual and sub‐annual time scales on spatially‐extensive landforms, such as river banks and bluffs. Terrestrial laser scanning (TLS) can be employed to address this need. TLS collects high‐resolution data allowing for more accurate monitoring of erosion rates and processes, and provides a new opportunity to make precise measurements of geomorphic change on vertical landforms like banks and bluffs, but challenges remain. This research highlights challenges and limitations of using TLS for change detection on river banks and bluffs including the presence of vegetation, natural surface crenulations, and difficulties with creating benchmarks, and provides solutions developed to overcome these limitations. Results indicate that data processing algorithms for change detection can have a significant impact on the calculated erosion rates, with different methods producing results that can vary by over 100%. The most accurate change detection technique compares a point cloud to a triangulated irregular network (TIN) along a set of vectors that accommodate bluff curvature. This paper outlines a variety of methods used to measure bluff change via TLS and explains the accompanying error analysis that supports these methods. Copyright © 2012 John Wiley & Sons, Ltd.
ISSN:0197-9337
1096-9837
DOI:10.1002/esp.3353