| Summary: | Thesis (M.S.) University of Alaska Fairbanks, 2020 In 2015, the Sagavanirktok River experienced a sequence of high, early-winter temperatures that lead to a buildup of aufeis. The buildup displaced the spring runoff causing widespread flooding. Flood waters inundated the surrounding tundra introducing heat into ground ice-baring soils. The Sagavanirktok River flood was caused by an extensive ice dam that developed the previous winter. The first flooding pulse started in April 2015, when an aufeis obstruction diverted river water to the surface. The obstruction caused flooding along 24 km of the Dalton Highway and its surroundings, necessitating a prolonged highway closure and emergency repairs. A second flooding pulse was caused by annual spring runoff in May 2015, which was driven by rapid snowmelt due to warm seasonal temperatures. The washed-out highway had to be closed again. Field investigations showed that thermal erosion of ice wedges in the tundra adjacent to the Dalton Highway caused local subsidence by several meters. However, the full environmental impact of the flood has not yet been quantified regionally or temporally. Thermokarst formation, can cause rapid ecological and environmental changes. Thawing of permafrost can lead to terrain instability as the melting of ground ice induces subsidence and loss of soil strength. The processes involved in permafrost degradation are complex, as is predicting terrain stability and the associated impacts to permafrost surrounding infrastructure. The immediate impact of the 2015 Sagavanirktok River flood is evident, which caused rapid terrain collapse in the vicinity of the Dalton Highway and the Trans-Alaska Pipeline near Deadhorse, North Slope Borough, Alaska. Thermal degradation of permafrost can be expressed as the change in the surfacemicrotopography over several years following a flood. Change detection, digital elevation model differencing, and InSAR were employed within the area of interest to understand the extent of the flood and deformation within ...
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