Using Synthetic Aperture Radar Imagery to Estimate Lake Water Depths on Alaska's North Slope - Celine van Breukelen, University of Alaska Fairbanks (co-authors: W. Schnabel, D. White, A. Tidwell, P. Prokein)

ABSTRACT

Winter water resources on Alaska’s North Slope are limited, and are necessary as an aquatic habitat and as a source of water for building and maintaining ice roads for oil and gas exploration.

The objective of this project is to determine the reliability of Synthetic Aperture Radar (SAR) to predict water quantity held in lakes on the North Slope, particularly between the Canning and Colville Rivers.

SAR imagery is combined with air temperature data to determine the date of freezing and subsequent water depth of lakes. The SAR imagery shows a noted difference in the return value of pixels which have frozen to the ground, and has been well documented by numerous researchers. The modified Stefans equation predicts ice thickness based on air temperature. Air temperatures are obtained from 9 meteorological stations distributed on the North Slope, including the National Climate Data Center (NCDC) station at Prudhoe Bay.

Two data sets are being used to ground truth the method. The first data set is comprised of over 100 ice thickness point measurements taken from the winters of 2006-09. This data set is used to calibrate the modified Stefans equation to estimate ice thickness based on air temperature. The second data set includes known bathymetry for 6 lakes on the North Slope. The bathymetry data set is used to verify the combination of the radar return and the calculated ice thickness.

Results from using the modified Stefans ice thickness equation to determine ice depth shows ice thicknesses can be predicted within ± 1.83 inches at the ± 95% confidence interval. Results from the bathymetry portion of the study are still pending, but will be available before March 30.

Topic: North Slope water