Abstract
The Colville is an Arctic river in the Alaska North Slope. The residents of Nuiqsut rely heavily on the Colville for their subsistence needs. Increased erosion has been reported on the Colville, especially along bluffs, which shaped the goals of this study: to use remote sensing techniques to map and quantify erosion rates and the volume of land loss at selected bluff sites along the main channel of the Colville, and to assess the suitability of automated methods of regional erosion monitoring. We used orthomosaics from high resolution aerial photos acquired in 1955 and 1979/1982, as well as high resolution WorldView-2 images from 2015 to quantify long-term erosion rates and the cubic volume of erosion. We found that, at the selected sites, erosion rates averaged 1 to 3.5 m per year. The erosion rate remained the same at one site and increased from 1955 to 2015 at two of the four sites. We estimated the volume of land loss to be in the magnitude of 166,000 m3 to 2.5 million m3 at our largest site. We also found that estimates of erosion were comparable for manual hand-digitized and automated methods, suggesting our automated method was effective and can be extended to monitor erosion at other sites along river systems that are bordered by bluffs.
Highlights
Erosion plays a significant role in the changing environment of a river
This process is unique to rivers flowing through continuous permafrost and results in higher bank erosion rates with increasing bank height, which is uncommon for non-periglacial rivers [2]
Given that the lateral bank erosion in the study sites was in the order of tens of meters, we found the input images appropriate for meeting our change detection needs
Summary
Erosion plays a significant role in the changing environment of a river. It affects water flow, water quality, channel width and depth, and safe use of a river as a transportation corridor. Warmer air and water temperatures lead to more pronounced thermal erosion and toe undercutting of ice-rich permafrost banks, resulting in erosion through massive block failures. This process is unique to rivers flowing through continuous permafrost and results in higher bank erosion rates with increasing bank height, which is uncommon for non-periglacial rivers [2]. 61% reported more or faster erosion along the Colville River than there used to be, and that increased erosion contributes to changes in the river environment; and 11% reported no change [5]
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