Rock Glacier Hydrological Significance in a Warming World: A Geoecological Transect in the North Cascades, Washington

• Main Author: Coffey, Jessica Abadie
• Format: Text
• Language: unknown
• Published: ScholarWorks@CWU 2021
• Subjects: Rock Glacier; Geomorphology; Climate; Ground Penetrating Radar; Water Resources; Cascades; permafrost
• Online Access: https://digitalcommons.cwu.edu/etd/1557; https://digitalcommons.cwu.edu/cgi/viewcontent.cgi?article=2582&context=etd

Mountain environments are some of the most climate-sensitive areas on the planet. Due to recent warming trends, the 0℃ isotherm is rising in elevation and subsequently melting glaciers, snowpack, and permafrost. However, rock glaciers are a type of permafrost that is climate-resilient; therefore, research on their distribution and water volume equivalence (WVEQ) will be increasingly valuable in a warming world. The purpose of this research was to determine the hydrological significance of different altitude belts of alpine permafrost in Washington State’s North Cascades. Additionally, this study analyzed how much rock glacier permafrost will be exposed to melting temperatures with climate change. In the North Cascades, field surveys using ground penetrating radar (GPR) were conducted on a sample of ten intact rock glaciers in an E-W geoecological transect. Based on the GPR surveys, the total WVEQ estimated for North Cascades rock glaciers in this study was 19,750,000 m3. Climate modeling was used to project the mean annual air temperature (MAAT) for each rock glacier by the year 2100 under different greenhouse gas emissions scenarios. This model projected a MAAT ≥ 3°C by 2100 for all 53 sites, indicating the rock glacier permafrost will be degrading. Nonetheless, rock glaciers are more climate-resilient than glaciers and snowpack, so they can potentially buffer the water scarcity this region will experience with climate change. Geoecological analysis revealed a minor relationship between continentality and rock glacier WVEQ in the North Cascades. Furthermore, rock glacier altitude distribution did not reveal an elevation range wherein rock glaciers developed preferentially. However, the WVEQ of rock glaciers substantially increased with elevation and nearly two-thirds of the total rock glacier WVEQ was confined within a 173 m elevation bracket, occupied by only one-third of the rock glaciers. This implies that water content may be distributed differently than can be observed by only recording rock glacier ...