Capturing water tracks using remote sensing in the foothills of the Alaskan Arctic: a multi-data perspective - Erin Trochim, University of Alaska Fairbanks (co-authors: D.L. Kane, A. Prakash)

ABSTRACT

Delineating drainage networks in the Alaskan Arctic is an important component for modeling and predicting hydrological processes. Water tracks are a dominant landscape feature in these drainage basins, and generally comprise the majority of the immature surficial drainage network as saturated linear-curvilinear features running roughly perpendicular to the slope. They effectively transport precipitation rapidly through a mantled organic layer, as flow is confined by the presence of continuous permafrost. In the study area in and around the Upper Kuparuk basin, mapping the physical characteristics of water tracks through remote sensing techniques and relating these features to their physical processes may allow characterization of how the landscape could change over time with variations in local, regional and global climate. Previous studies have used fractal analysis and qualitative determination to map water tracks in the Imnavait and Upper Kuparuk basins. In this research, remote sensing techniques were applied to multispectral data from the ALI sensor on the EO-1 satellite to characterize NDVI, a tasseled cap soil moisture index, and linear unmixing of common ground covers like Salix pulchra, Betula nana, and various mosses. SAR imagery with a 5-m spatial resolution was used as a threshold for defining areas where water tracks were most likely, and then the results from the multispectral classification were applied. Imagery from the ALOS satellite which contained quad-pol amplitude data was also analyzed. The results from both classifications were then evaluated against ground-verified data collected during the summers of 2008 and 2009. This methodology revealed that water tracks could be accurately mapped using a semi-automated approach and that their unique vegetation and soil moisture characteristics could be separated from the surrounding topography.

Topic: Permafrost hydrology