Intermittent Channel Systems of a Low‐Relief, Low‐Gradient Floodplain: Comparison of Automatic Extraction Methods
Intermittent Channel Systems of a Low‐Relief, Low‐Gradient Floodplain: Comparison of Automatic Extraction Methods
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DOI：
10.1029/2020wr027603
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发表时间：
2020-08
影响因子：
5.4
通讯作者：
Haiqing Xu;S. Steeg;J. Sullivan;D. Shelley;J. E. Cely;E. Viparelli;V. Lakshmi;R. Torres
中科院分区：
文献类型：
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作者：
Haiqing Xu;S. Steeg;J. Sullivan;D. Shelley;J. E. Cely;E. Viparelli;V. Lakshmi;R. Torres
间歇性洪泛区渠道是蚀刻在洪泛区表面的低起伏管道，一年中大部分时间保持干燥。这些渠道包括膨胀系统，并且很重要，因为在低水位淹没期间，它们促进了整个洪泛区的横向水力连通性。然而，很少有研究集中在这些河漫滩渠道由于不确定性，如何识别和描述这些系统的数字高程模型（DEM）。特别是，由于洪泛区的低起伏和低坡度地形特征，从广泛可用的DEM中自动提取它们具有挑战性。我们应用三个通道提取方法的Congaree河洪泛区DEM和比较的结果，通过在过去的30年中的许多实地考察创建的通道参考地图。我们测试的方法分别基于流量累积面积、地形曲率和数学形态学，或D8、拉普拉斯和底帽变换（BHT）。在198 km的参考通道中，BHT、Laplacian和D8分别提取了83%、71%和23%，并且BHT在局部（5 m）和区域（10 km）尺度上始终与参考网络具有最高的一致性。提取结果还包括委员会“错误”，增加了约100公里的通道长度的参考地图。总的来说，BHT方法为河道提取提供了最好的结果，在69 km2中提供了超过298 km的河道，消除趋势的区域地形为1.9 m。此外，这些分析使我们能够阐明“低起伏景观”一词的含义和用途。
Intermittent floodplain channels are low‐relief conduits etched into the floodplain surface and remain dry much of the year. These channels comprise expansive systems and are important because during low‐level inundation they facilitate lateral hydraulic connectivity throughout the floodplain. Nevertheless, few studies have focused on these floodplain channels due to uncertainty in how to identify and characterize these systems in digital elevation models (DEMs). In particular, their automatic extraction from widely available DEMs is challenging due to the characteristically low‐relief and low‐gradient topography of floodplains. We applied three channel extraction approaches to the Congaree River floodplain DEM and compared the results to a channel reference map created through numerous field excursions over the past 30 years. The methods that we tested are based on flow accumulation area, topographic curvature, and mathematical morphology, or the D8, Laplacian, and bottom‐hat transform (BHT), respectively. Of the 198 km of reference channels the BHT, Laplacian, and D8 extracted 83%, 71%, and 23%, respectively, and the BHT consistently had the highest agreement with the reference network at the local (5 m) and regional (10 km) scales. The extraction results also include commission “error”, augmenting the reference map with about 100 km of channel length. Overall, the BHT method provided the best results for channel extraction, giving over 298 km in 69 km2 with a detrended regional relief of 1.9 m. Further, these analyses allow us to shed light on the meaning and use of the term “low‐relief landscapes”.