Morphometric and spatial analysis of thaw lakes and drained thaw lake basins in the western Arctic Coastal Plain, Alaska

Abstract

Landsat-7 ETMþ scenes were acquired for the western Arctic Coastal Plain of Alaska extending from 152 to 162 W longitude. A segmentation algorithm was used to classify lakes and drained thaw lake basins (DTLBs) exceeding 1 ha in size. A total of 13,214 lakes and 6539 DTLBs were identified. Several indices were obtained from the image processing software and used for a comparative analysis of lakes and basins including object size, goodness of elliptic fit, shape complexity, shape asymmetry, and orientation of the major axis. Nonparametric statistical analyses indicate that lakes and basins share similar orientation only. Three subregions of the western Arctic Coastal Plain were identified based on landscape age, as demarcated by ancient shorelines. The surfaces become progressively older inland and include the Younger Outer Coastal Plain, the Outer Coastal Plain, and the oldest Inner Coastal Plain. Lakes and basins in all subregions have statistically similar orientation, indicating that summer wind direction has not changed appreciably over the past several thousand years. Basin orientation is less clustered than lake orientation. Lakes are highly elliptical, while basins have more complex shapes. Lake coverage (%) is fairly constant across the three subregions, while DTLB coverage decreases on older surfaces. Lake and basin size decreases on progressively older surfaces, but the number of features per unit area increases. It is uncertain if surface age is responsible for differences in regional metrics as an analysis of the Inner Coastal Plain demonstrates significant internal variation. Distance from the coast, ground ice content, surficial sediments, and local relief may also influence lake morphometry.

Spatial analyses of thermokarst lakes and basins in Yedoma landscapes of the Lena Delta

“…On the North American Arctic Coastal Plain, preferential erosion of the lake shores at right angles to prevailing summer wind directions due to wind-driven currents and wave activity has been proposed and agrees well with current main wind directions (e.g. Carson and Hussey, 1962;Côté and Burn, 2002;Hinkel et al, 2005); however, authors investigating orientation and directed evolution of thermokarst lakes and basins in Siberian Ice Complex deposits discuss solar insolation (e.g. Soloviev, 1962;Boytsov, 1965;Ulrich et al, 2010) and erosion due to wave activity in the direction of prevailing summer winds (e.g.…”

“…This adds a high percentage to the area of Ice Complex degradation due to thermokarst, which is 22.2 % of the study area. In Alaska, on the North Slope thermokarst lakes and drained basins cover a combined area of 46.1 % , and on the Barrow Peninsula 72 % (Hinkel et al, 2003). The remaining 77.8 % of our study area cannot be considered undisturbed Yedoma surfaces as thermal erosion also plays an important role in Ice Complex degradation.…”

Late Quaternary paleoenvironmental records from the western Lena Delta, Arctic Siberia

“…The surface morphology of the second terrace is largely characterized by NNW-SSE-oriented thermokarst depressions often containing lakes (Fig. 1B, C) resembling similar structures on other Arctic plains such as Alaska's North Slope (Hinkel et al, 2005). The dimensions of these thermokarst features cannot be related to current ground ice conditions of the mostly sandy facies of the second terrace but are likely linked to fluvial depressions which originated in a paleo-Lena River bed (Schwamborn et al, 2002a).…”

Nonlinear controls on evapotranspiration in arctic coastal wetlands

“…Low-centered ice-wedge polygons are found at the vegetated, drained thaw lake basin while high-centered icewedge polygons cover the upland areas of the watershed. Vegetated, drained thaw lake basins (Mackay, 1963) occupy approximately 26 % of the Arctic Coastal Plain (Hinkel et al, 2005) and 50 % of the Barrow Peninsula north of ∼71 • latitude (Hinkel et al, 2003). Longer-term (>2 yr) energy balance measurements of vegetated, drained thaw lakes are limited, constraining our understanding of interannual controls of evapotranspiration rates from this vast region.…”