2008 Alaska Park Science Symposium
October 14, 2008
Interpreting the Spatial Heterogeneity of Lake Drying in the Minchumina
Basin, Central Alaska
Amy S. Larsen1, Dave Verbyla2
1Central Alaska Network Inventory and Monitoring Program, National Park Service, 4175 Geist Road, Fairbanks, AK, 99709, USA, amy_larsen@nps.gov
2Department of Forest Sciences, University of Alaska Fairbansk, 366 O'Neill Building, Fairbanks, AK, 99775-7200, USA
The Minchumina Basin is a large wetland complex located in the northwestern
corner of Denali National Park and Preserve. Underlain by a mosaic of
discontinuous and continuous permafrost, the wetland is the site of Central
Alaska Network’s Shallow Lake Monitoring program. Here we aim to understand
the hydrologic dynamics of this diverse system. Understanding the physical
structure and temporal variation in lake level can provide critical
information to interpreting the spatial heterogeneity in lake drying found
throughout the boreal forest.
Lake surface area estimates were made using RADARSAT imagery collected
monthly over the course of the 2006 growing season in the Minchumina Basin.
We used these images to identify wetlands within the park that experience
varying degrees of connectivity. We also measured lake surface area in high
altitude infrared photographs taken in 1979 and 1980 and compared those
measurements to Landsat tm images taken in 2007. These measurements provide
us with an estimate of long-term water level declines. Using ground
monitoring techniques we try to relate bathymetry, water quality, soil type
and distribution of discontinuous and continuous permafrost to patterns of
connectivity and lake drying.
On-the-ground field observations and ground-truthing demonstrate a variety
of limitations in the interpretation of remote sensed data used for
estimating lake area. Particularly noteworthy is the measurable decline in
water level on what appear to be stable lake ecosystems.
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