| Summary: | Thesis (M.S.) University of Alaska Fairbanks, 2011 Thermokarst lakes develop when changes in the permafrost thermal regime cause degradation leading to surface subsidence and ponding. The degree of thermokarst development depends upon permafrost characteristics, topography, and geology. Changing thermokarst lake dynamics affect arctic ecosystems, hydrological patterns, albedo, and the carbon cycle through the mobilization of organic matter in the permafrost. This study used remote sensing and GIS techniques to relate lake dynamics in the Kolyma Lowlands, Siberia, to geology, elevation, geomorphological features, hydrology, and air temperature. Highest limnicity and largest lake sizes were found in regions with low elevation, limited alluvial processes, high ground-ice content, and lithologies with small particle sizes. New lake development and erosion occurred as well. One subregion studied showed lake area increases (Cherskii: +7.6%) while another showed a decrease (Duvanny Yar: -5.2%). Differences are attributed to variations in elevation and fluvial influences. A major cause of drainage was river tapping of lakes. Lake coalescence, flooding during river water level high stands, and lakeshore erosion were the main causes of lake expansion. The Kolyma Lowland soils have high ice and organic matter contents as well making the monitoring of thermokarst lake dynamics important as large amounts of freshwater and carbon could potentially be released. 1. Introducton -- 1.1. Permafrost and climate change -- 1.2. Thermokarst lakes -- 1.3. Changes during the Pleistocene-Holocene transition -- 1.4. Previous Siberian lake change studies -- 1.5. Goal of this research -- 2. Study region -- 3. Methods -- 3.1. Medium-resolution landsat images -- 3.2. High-resolution images -- 3.3. Non-image data sources -- 3.4. GIS analysis -- 3.4.1. Geo-referencing and image mosaics -- 3.4.2. Digitizing of the lakes -- 3.4.3. Remaining data processing -- 3.5. Regions of lake analysis -- 3.5.1. High-resolution study regions -- 3.5.2. ...
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