A new method for deriving glacier centerlines applied to glaciers in Alaska and northwest Canada

This study presents a new method to derive centerlines for the main branches and major tributaries of a set of glaciers, requiring glacier outlines and a digital elevation model (DEM) as input. The method relies on a "cost grid–least-cost route approach" that comprises three main steps. Fi...

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Bibliographic Details
Published in:The Cryosphere
Main Authors: C. Kienholz, J. L. Rich, A. A. Arendt, R. Hock
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2014
Subjects:
geo
Online Access:https://doi.org/10.5194/tc-8-503-2014
http://www.the-cryosphere.net/8/503/2014/tc-8-503-2014.pdf
https://doaj.org/article/653d9dfd83c94e57be3229955ca0a6ba
Description
Summary:This study presents a new method to derive centerlines for the main branches and major tributaries of a set of glaciers, requiring glacier outlines and a digital elevation model (DEM) as input. The method relies on a "cost grid–least-cost route approach" that comprises three main steps. First, termini and heads are identified for every glacier. Second, centerlines are derived by calculating the least-cost route on a previously established cost grid. Third, the centerlines are split into branches and a branch order is allocated. Application to 21 720 glaciers in Alaska and northwest Canada (Yukon, British Columbia) yields 41 860 centerlines. The algorithm performs robustly, requiring no manual adjustments for 87.8% of the glaciers. Manual adjustments are required primarily to correct the locations of glacier heads (7.0% corrected) and termini (3.5% corrected). With corrected heads and termini, only 1.4% of the derived centerlines need edits. A comparison of the lengths from a hydrological approach to the lengths from our longest centerlines reveals considerable variation. Although the average length ratio is close to unity, only ~ 50% of the 21 720 glaciers have the two lengths within 10% of each other. A second comparison shows that our centerline lengths between lowest and highest glacier elevations compare well to our longest centerline lengths. For > 70% of the 4350 glaciers with two or more branches, the two lengths are within 5% of each other. Our final product can be used for calculating glacier length, conducting length change analyses, topological analyses, or flowline modeling.