An Assessment Of Suspended Sediment Transport In Arctic Alaskan Rivers PDF Download

The effects of climate change are increasing the vulnerability the delicate Arctic system on the North Slope of Alaska. Concurrently, oil and gas development is projected to expand across the region, the wide-scale effects of which are largely unknown in a less-resilient system. This research provides the framework for using satellite data to assess and monitor suspended sediment conditions in the nearshore Alaskan Beaufort Sea, which provide a key indicator of environmental change. Satellite monitoring of suspended sediment levels provides a cost-effective means to obtain nearly real-time, synoptic information about environmental change on the North Slope. This information can be incorporated into cumulative effects analyses and enhance their capability to assess and predict the environmental effects of oil and gas development in a changing climate. Surface reflectance data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Very High Resolution Radiometer (AVHRR) sensors were calibrated to total suspended sediment (TSS) concentrations in the Alaskan Beaufort Sea and used to construct time series of proxy TSS data for 2000-2005 and 1981-2004, respectively. These time series produced a baseline quantifying the interannual variability and 24-year trends in median annual TSS concentrations at locations in the nearshore Alaskan Beaufort Sea. Increasing trends over the analysis period were identified in the outflow areas of the Ikpikpuk, Colville, Kuparuk and Sagavanirktok rivers, as well as in Admiralty Bay. Additionally, TSS levels in 1994 and 2000 exceeded the normal range of variability at several of the nearshore locations investigated. Different areas along the nearshore had varying TSS magnitudes and modes of variability, a function of the terrestrial and nearshore processes controlling TSS conditions at each location. An empirical model explained 65 percent of the variability in annual median TSS values using precipitation factors that parameterized sediment supply and transport mechanisms. High annual median TSS levels in the Colville River from the late 1980s, coinciding with significant oil and gas development in the Colville River basin, were not explainable by natural factors in the empirical model.