Bank erosion processes measured with UAV-SfM along complex banklines of a straight mid-sized river reach
<p>We apply structure from motion (SfM) photogrammetry with imagery from an unmanned aerial vehicle (UAV) to measure bank erosion processes along a mid-sized river reach. This technique offers a unique set of characteristics compared to previously used methods to monitor banks, such as high...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-10-01
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| Series: | Earth Surface Dynamics |
| Online Access: | https://www.earth-surf-dynam.net/6/933/2018/esurf-6-933-2018.pdf |
| Summary: | <p>We apply structure from motion (SfM) photogrammetry with imagery from an
unmanned aerial vehicle (UAV) to measure bank erosion processes along a
mid-sized river reach. This technique offers a unique set of characteristics
compared to previously used methods to monitor banks, such as high resolution
and relatively fast deployment in the field. We analyse the retreat of a
1.2 km restored bank of the Meuse River which has complex vertical scarps
laying on a straight reach, features that present specific challenges to the
UAV-SfM application. We surveyed eight times within a year with a simple
approach, combining different photograph perspectives and overlaps to
identify an effective UAV flight. The accuracy of the digital surface models
(DSMs) was evaluated with real-time kinematic (RTK) GPS points and airborne
laser scanning of the whole reach. An oblique perspective with eight photo
overlaps and 20 m of cross-sectional ground-control point distribution was
sufficient to achieve the relative precision to observation distance of ∼ 1 : 1400 and 3 cm root mean square error (RMSE), complying with the
required accuracy. A complementary nadiral view increased coverage behind
bank toe vegetation. Sequential DSMs captured signatures of the erosion cycle
such as mass failures, slump-block deposition, and bank undermining. Although
UAV-SfM requires low water levels and banks without dense vegetation as many
other techniques, it is a fast-in-the-field alternative to survey reach-scale
riverbanks in sufficient resolution and accuracy to quantify bank retreat and
identify morphological features of the bank failure and erosion processes.
Improvements to the adopted approach are recommended to achieve higher
accuracies.</p> |
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| ISSN: | 2196-6311 2196-632X |