About half of the Arctic Coastal Plain (ACP) of North America is covered with thaw lakes and the basins that form when lakes drain, making these features the dominant landscape elements and a crucial component of the Arctic system. Lake formation was apparently initiated during the warmer early Holocene, and recent evidence from the continuous permafrost zone of Western Siberia and North America suggests that thaw lakes are experiencing rapid changes in response to increasing air temperature and direct human-induced perturbations.
To date, our understanding of the processes leading to thaw-lake formation, expansion, and drainage on the ACP is limited. Most process-based hydrologic and hydrodynamic studies were conducted half a century ago on lakes developed on the flat, young Outer (seaward) Coastal Plain. This region comprises only 1/3 of the ACP, and has geomorphic characteristics fundamentally different from the more extensive Inner Coastal Plain. In addition, spatial and temporal analysis of lake coverage, drainage, and morphometry (size and shape) has been largely restricted to the period since the mid-1970s when satellite images first became available. This project will make a systematic effort to collect and synthesize information on thaw-lake changes to understand the basic geomorphic processes influencing a landscape responding to climatic amelioration.
A regional assessment across the ACP will be conducted using existing satellite images to detect changes in lake coverage and morphometry during the satellite era. The group will also use digital aerial photographs to extend the analysis back to ~1950 for ten subregions of the ACP, and assess temporal patterns of change. These data will be supplemented by existing spatial data sets including ground ice content, surficial sediments, vegetation and high resolution digital elevation models, which are used in a Geographic Information System modeling environment to determine if lakes are responding to warming climate in a spatially consistent manner. These analyses will be augmented by summer field studies focused on lake evaporation and shoreline erosion in three study areas. The measurement program is designed to map patterns of shoreline changes, monitor interannual variations in lake levels, and estimate energy and moisture exchange between lakes and the atmosphere.
The four scientific goals and the methods that address the intellectual merits of the research are: (1) using an accurate co-registered ACP mosaic of satellite scenes from the mid-1970s and post 2000, identify and map lakes that have enlarged, contracted, or drained over the period to assess regional response to observed warming; (2) using digital versions of circa 1950 aerial photographs, analyze changes in lake morphology and coverage for the period since 1950 for ten subregions of the ACP; (3) in three study areas on a coastal-to-inland transect across the ACP, conduct intensive studies of lake energy and water budgets, evaporation, and shoreline erosion to replicate and expand on similar studies conducted during the International Geophysical Year fifty years ago; and (4) synthesize a variety of existing digital data sources including maps of ground ice content, surficial sediments, vegetation, and digital elevation data to develop causative models relating susceptibility of lake change to local landscape characteristics.
