High-resolution topographic data (TLS and SfM) of river bluffs in Amity Creek and the Knife River, Minnesota, USA, 2016-2018

Over the past few years, more and more river bluffs on North Shore (Minnesota, USA) streams are being stabilized using a technique wherein a bankfull bench is created adjacent to an eroding bluff using a combination of toe wood, rock, and soil lifts. One of the goals of this technique is to reduce the amount of fine sediment entering the river from bluff erosion, both by removing river access to the toe of the bluff and by providing a bench for eroding sediment to deposit on. In order to determine how much erosion and deposition were occurring on these bluffs, we monitored six river bluffs on the Knife River and Amity Creek from 2016-2018. We report data on four bluffs in Amity Creek and two in the Knife River: 4 bluffs that were stabilized in the 2014 and 2015 using a bankfull bench design and 2 additional bluffs that have not had work done on them for comparison. Each bluff was surveyed 2-3 times each between 2016 and 2018 using a Faro Focus 3D terrestrial laser scanner (TLS), and all four stabilized bluffs were surveyed once via photogrammetry from a DJI Phantom 4 UAV (uncrewed aerial vehicle). The photogrammetry data were turned into high-resolution topographic data using Structure-from-Motion (SfM) processing. Repeat data at each site were compared using Geomorphic Change Detection to calculate volumes of change. In addition, SfM and TLS data collected simultaneously are compared to test the efficacy of using photogrammetry data to monitor bluff erosion.

过去几年，美国明尼苏达州北岸溪流的越来越多河岸悬崖正通过一种技术得到稳定——该技术通过组合使用坡脚木材（toe wood）、岩石和土层（soil lifts），在侵蚀悬崖旁构建满岸阶地（bankfull bench）。该技术的目标之一是减少悬崖侵蚀产生的细颗粒沉积物进入河流，方法包括阻断河流对悬崖坡脚的侵蚀通道，以及提供阶地供侵蚀沉积物沉积。为确定这些悬崖的侵蚀和沉积量，我们于2016-2018年监测了Knife河和Amity溪的6处河岸悬崖。我们报告了Amity溪4处和Knife河2处悬崖的数据：其中4处悬崖于2014-2015年采用满岸阶地设计进行了稳定处理，另外2处未做任何处理以作对照。2016-2018年间，每处悬崖使用Faro Focus 3D地面激光扫描仪（terrestrial laser scanner, TLS）进行了2-3次测量；所有4处稳定处理过的悬崖还通过大疆Phantom 4无人机（uncrewed aerial vehicle, UAV）摄影测量法进行了一次测量。摄影测量数据通过运动恢复结构（Structure-from-Motion, SfM）处理转换为高分辨率地形数据。各站点的重复数据通过地貌变化检测（Geomorphic Change Detection）进行对比，以计算变化量。此外，同步采集的SfM和TLS数据被对比，以验证使用摄影测量数据监测悬崖侵蚀的有效性。