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Application of globally available, coarse‐resolution digital elevation models for delineating valley bottom segments of varying length across a catchment
Author(s) -
Khan Sana,
Fryirs Kirstie A.
Publication year - 2020
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.4930
Subject(s) - digital elevation model , landform , remote sensing , scale (ratio) , geology , elevation (ballistics) , lidar , geomorphology , cartography , geography , geometry , mathematics
The worldwide availability of digital elevation models (DEMs) has enabled rapid (semi‐)automated mapping of earth surface landforms. In this paper, we first present an approach for delineating valley bottom extent across a large catchment using only publicly available, coarse‐resolution DEM input. We assess the sensitivity of our results to variable DEM resolution and find that coarse‐resolution datasets (90 m resolution) provide superior results. We also find that LiDAR‐derived DEMs produce more realistic results than satellite‐derived DEMs across the full range of topographic settings tested. Satellite‐derived DEMs perform more effectively in moderate topographic settings, but fail to capture the subtleties of valley bottom extent in mild gradient, low‐lying topography and in narrow headwater reaches. Second, we present a semi‐automated technique within ArcGIS for delineating valley bottom segments using DEM‐derived network scale metrics of valley bottom width and slope. We use an unsupervised machine‐learning technique based on the k ‐means clustering algorithm to solve a conundrum in GIS‐based geomorphic analysis of rivers: the delineation of valley bottom segments of variable length. The delineation of valley bottom segments provides a coarse‐scale entry point into automated geomorphic analysis and characterization of river systems. © 2020 John Wiley & Sons, Ltd.