A New Scheme of Time Series Glacial Lake Mapping for Outburst Flood Monitoring in the West Tienshan Mountains

Authors: Junli Li*, Xinjiang Institute of Ecology ang Geography, Chinese Academy of Sciences, Timothy Warner, Department of Geology and Geography, West Virginia University
Topics: Hazards, Risks, and Disasters, Mountain Environments, Water Resources and Hydrology
Keywords: glacial Lake, mountain shadow, lake mapping, Tienshan Mountains
Session Type: Poster
Day: 4/5/2019
Start / End Time: 8:00 AM / 9:40 AM
Room: Lincoln 2, Marriott, Exhibition Level
Presentation File: No File Uploaded

Mountain shadows in optical satellite images complicate the mapping of glacial lakes. Due to the rugged topography in periglacial alpine regions, many glacial lakes, especially smaller lakes, are partially shaded by mountain shadows in remotely sensed images. Shadows not only reduce accuracy of lake mapping, but also make changes in lake area hard to detect. In this paper, the characteristics of mountain shadows in remotely sensed imagery are explored, and their spatial relationships with regards to glacial lakes are modelled. Building on the previously developed Glacial Lakes Iterative Local Mapping (GLILM) method, a new water mapping scheme is presented. The new method utilizes log-transformed spectral data and a normalized difference water index, NDWIblue, for delineating the boundaries of lakes within shadowed regions. The application of this approach is explored within the context of mapping lakes across space and time using Landsat images in the glacially dominated Tianshan mountainous of Central Asia. The results demonstrate that glacial lakes, both in sunlit and in shaded areas, can be mapped reliably, and that the results are useful for lake change analysis studies.

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