GIS analysis of the spatial dynamics of thermokarst lake shores in the Teshekpuk Lake region (Alaska) using historical remote sensing data

• Main Author: Simonenkova, Kseniia
• Format: Thesis
• Language: unknown
• Published: 2015
• Subjects: permafrost; Thermokarst; Alaska
• Online Access: https://epic.awi.de/id/eprint/39650/; https://hdl.handle.net/10013/epic.46765

The objectives of my study were (1) development of methods for thermokarst lakes changes studying using GIS technology; (2) to analyze spatial variability of thermokarst lake shore between 1955 and 2004 in the region Teshekpuk Lake (Alaska) using historical high spatial resolution (1m) remote sensing data; (3) to identify potential mechanisms of lake expansion and lake reduce (causes and dependence on environmental factors). The methodology of this study on thermokarst lake dynamics is based on a combination of remote sensing (RS), Geographical Information Systems (GIS) and Statistical methods. To quantify of the permafrost change in the Teshekpuk Lake region I selected 49 aerial images, obtained in the summer months from 1948 to 2004. I georeferenced the historical images using an already orthorectified mosaic of aerial images from 2004 as base map. Taking into account water bodies larger than 1 ha in the 700 km2 study area, I mapped the shorelines of 56 thermokarst lakes in different time periods (1948, 1955, 1979 and 2004) using manual digitizing in ArcGIS. Of these, 13 lakes were analyzed for erosion rates using the Digital Shoreline Analysis System tool (DSAS) for two time periods, 1955 to 1979 and 1979 to 2004. The shore change rates were then analyzed in relation to climate data including wind speed and direction. As a result, I conclude that the lake-rich landscape of Teshekpuk Lake region change dynamically on decadal time scales and thus also affects the spatial distribution on near-surface permafrost. On the one hand, lake area is lost due to rapid lake drainage, on the other side, permafrost thaw and shore erosion increases the area of some lakes. Climate data analysis for the period 1950-2014 has shown that the dynamics of thermokarst lakes depends on more than one factor. Changes of thermokarst lakes are determined by a complex of cooperating factors, such as increase of air temperature, the activity of watercourse connecting lakes and the amount of precipitation.