HR: 1340h
AN: H53D-1450    [Abstracts]
TI: Geographic Analysis of Alaska Lake Districts
AU: * Arp, C D
EM: carp@usgs.gov
AF: U.S. Geological Survey, Alaska Science Center, 4230 University Dr., Anchorage, AK 99508- 4664, United States
AU: Jones, B M
EM: bjones@usgs.gov
AU: Zimmerman, C E
EM: czimmerman@usgs.gov
AB: The state of Alaska has over 400,000 lakes greater than 0.01 km² in surface area covering approximately 3.3% of the landscape. As in most lake-rich regions, these lakes are unevenly distributed on the landscape. So in order to better understand how lakes are organized on the landscape and relate this geographic organization to other climatologic, geologic, and biogeographic characteristics, we analyzed the spatial distribution of Alaska lakes. Using a combination of numerical abundance and surface-area extent of lakes, we selected lake density thresholds to identify and delineate 22 lake districts in Alaska. The total area of these 22 lakes districts occupy 16% of Alaska, yet encompass 64% of lakes and 76% of lake surface-area. The three largest lake districts are associated with the Yukon-Kuskokwin Delta, the Northern Arctic Coastal Plain, and the mountain front of the Alaskan Range on the Alaska Peninsula. Interestingly, these largest lake districts are covered by >17% lakes, while most of the smaller lake districts we identified have <10% lake cover. Of the remaining smaller lake districts, 9 are associated with mountain fronts or intermountain basins, 4 are associated with coastal plains, 3 are associated with floodplains and deltas, and 3 occur in high-elevation or mountain terrain. The highest numerical lake densities occur at deltas, while relatively lower densities occur in mountainous areas where individual lakes are often larger in surface area and likely volume. Comparison of these lake districts were made to permafrost distribution, glacial history, lithology, watershed position, and regional hydrologic budgets and regimes to better understand where lake-rich regions occur, why, and how they might change in the future. Ten of the 22 lake districts occur in areas dominated by continuous permafrost, 6 occur in areas of discontinuous or sporadic permafrost, and the other 6 occur in regions without perennially frozen soils. The majority of lake districts, 63% occur in regions that were glaciated during the last glacial maximum, yet several of the largest lake districts occur in unglaciated terrain. We also made comparisons of lake districts to other natural units used for landscape analysis including ecoregions and watersheds, and human- delineated units including National Parks (NP) and National Wildlife Refuges (NWR). Not surprisingly, 12 of these lake districts occur partly or wholly within NWRs, and all but two are associated with other state or federally managed parks or wildlife refuges. Analysis of lake districts in Alaska, or other regions on Earth, may prove to be useful for better understanding lake change, aquatic and terrestrial habitats, and regional hydrologic budgets and regimes. Such fresh views of the landscape may become increasingly important for improving natural resource science and management in Alaska, where future climate change is predicted to be very rapid.
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 0475 Permafrost, cryosphere, and high-latitude processes (0702, 0716)
DE: 0746 Lakes (9345)
DE: 1824 Geomorphology: general (1625)
DE: 9315 Arctic region (0718, 4207)
SC: Hydrology [H]
MN: 2007 Fall Meeting