| Summary: | Thesis (M.S.) University of Alaska Fairbanks, 2015 Glaciers play an important role in both storage and generation of runoff within individual watersheds. The Valdez Glacier catchment (342 km²), located in southern Alaska in the Chugach mountains off of Prince William Sound, is characterized by large annual volumes of rain- and snowfall. As Valdez Glacier and other glaciers within the catchment (comprising 58% of the catchment area) continue to melt in a warming climate, it is unclear how the runoff will be affected. Temperature-index modeling is one method used to estimate glacier mass balance and runoff in highly glacierized catchments, and may be suitable for predicting future runoff regimes. In this study, we used a combination of field measurements (air temperature, glacier mass balance, streamflow, and ground-penetrating radar (GPR)-derived snow water equivalent (SWE) from a parallel study) and modeled climate data (PRISM) to a) calibrate a temperature-index model to glacier mass balance in 2012; b) validate the model to laser altimetry; and c) calibrate a temperature-index model to runoff measurements in fall of 2012 and in spring, summer and fall of 2013. We calibrated the snow-radiation coefficient (r_snow), ice-radiation coefficient (r_ice), and melt factor (MF) of the temperature-index model to glacier mass balance measurements from 2012. Using the calibrated- r_snow, r_ice, and MF (i.e. r_snow, r_ice, and MF = 0.20, 0.50 and 4.0, respectively), we calculated 2012 annual glacier mass balance (Ba) at 0.05 ± 0.49 meters water equivalent (m w.eq.). We next validated the model to 2012 laser altimetry annual glacier mass balance estimates (Ba = 0.20 ± 0.6 m w.eq.). We then modeled glacier mass balance in 2013 using r_snow, r_ice, and MF from the 2012 calibration. The model underestimated summer glacier mass balance in 2013, resulting in annual glacier mass balance (Ba = 0.55 m w.eq.) that did not fall within the 2013 laser altimetry annual balance estimate (Ba = -1.15 +0.29/-0.30 m w.eq.). We therefore ...
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