201. Shean et al. (2017) A high-resolution DEM record for Mt. Rainier and CONUS glaciers: Geodetic mass balance, glacier dynamics, snow depth and natural hazards
     Mountain glaciers represent only ~1% of the total freshwater on Earth, yet due to increasing mass imbalance, they are responsible for ~30% (~1 mm/yr) of present-day sea level rise. On a regional scale, they are indicators of climate change and serve as important seasonal/long-term hydrologic reservoirs. We generated ~500 high-resolution digital elevation models (DEMs) from sub-meter commercial stereo imagery (DigitalGlobe WorldView/GeoEye constellation) acquired over glaciers in the Contiguous US (CONUS) from 2008-present. We produced a ~2015 DEM mosaic and estimated ~5-10 year and long-term (~30-60 year) geodetic mass balance for ~700 glaciers larger than 0.1 km² using airborne LiDAR data from ~2008-2010 and National Elevation Dataset (NED) data with source dates of ~1950-1980. These results provide new information about the spatial distribution and evolution of CONUS glacier mass balance, with greatest loss rates observed for high-latitude, low-elevation glaciers. We also generated monthly to interannual DEM time series for high-priority sites, including >40 stereo DEMs from 2014-2016 for Mt. Rainier. This record offers new details about seasonal snow accumulation and redistribution on Mt. Rainier, including high-elevation areas near the summit with limited in situ observations. We generated high-resolution velocity maps and document dynamic surface elevation anomalies (+/-20-30 m) for a subset of Mt. Rainier's fast-flowing glaciers. These efforts will provide basin-scale estimates of snow water equivalent (SWE) and snow/ice melt runoff contributions for downstream water resource applications (e.g., hydropower, irrigation, municipal use). Finally, these observations also document dynamic landscape evolution (e.g., landslides, sediment redistribution) that can be used for both hazard assessment and rapid response to natural disasters (e.g., outburst floods).
514. Seitzinger et al. (2024) Adaptive management in the National Park Service: How Mount Rainier has grown and responded to imminent geomorphic threats
     The Imminent Threats Program at Mount Rainier National Park (MORA) is a novel addition to the typical structure of the National Park Service’s (NPS) Natural and Cultural Resources (NCR) divisions, operating as a branch of the distinguished Geology program. The landscape of MORA is characterized by steep, mountainous terrain; the very nature of the braided, glacier-fed rivers that cascade through this terrain is to change shape and structure constantly as sediment transport conditions vary. Such dynamic geomorphic surface processes pose complicated conditions for maintaining access throughout the park, affecting the integrity and longevity of park infrastructure, such as roadways, bridges, and trails. Recurrent damage to infrastructure proves that traditional maintenance and engineering techniques utilized for repairs do not work in the local environment. The need of a focused geomorphic risk group to address such inertia became identified in the early 2000’s and exists now formally as the Imminent Threats Program. The Imminent Threats technicians conduct scientific monitoring within the park to collect relevant observations of surface processes. This local knowledge is supported by additional literature review and is then used by the technicians to advise and implement holistic engineering designs fit to exist within rather than dominate the environment. The technicians also aim to influence the cultural perception of change and response to infrastructure damage within the agency workplace through their presence at interdisciplinary policy meetings, and also broader society through educational outreach. The long-running success of the projects they’re involved in encourages the Imminent Threats Program to continue to grow and influence the use of adaptive management techniques while responding to reparative needs in the park, ultimately creating improved, effective, and holistic change in resource management at MORA.
513. Todd and Jimenez (2024) Time-lapse monitoring of a small mountain glacier to capture debris flow activity
     South Tahoma Glacier is a 2 km² glacier in Mount Rainier National Park, WA that has produced 31 known debris flows since 1967, more than any other glacier on Mount Rainier. These geologic hazards threaten infrastructure and human lives along Tahoma Creek, downstream from the glacier terminus. The timing of these events and previous research suggests that debris flows from South Tahoma Glacier are most likely triggered by glacial outburst floods, which result when subglacial water storage increases due to (a) increased melt from a period of high temperatures, or (b) late summer or fall precipitation events. We installed a time lapse camera after a series of destructive debris flows in August 2015, and have monitored the glacier terminus from July - September, 2016 - 2023; we will reinstall a time lapse camera in summer 2024. We combine time lapse imagery with meteorological data, high resolution satellite imagery, and digital elevation models to investigate the relationship between recent debris flows and changes to the glacier terminus and proglacial meltwater channels. Our findings will document precursors to and impacts of debris flows from South Tahoma Glacier.
512. Ruzzante and Gleeson (2024) Increasingly hot and dry summers exacerbate low flows and threaten pacific salmon habitat throughout Northwestern North America
     Excessively low stream flows in the late summer can disrupt aquatic life cycles, including those of ecologically and culturally significant species such as Pacific Salmon. Climate change is expected to drive hydrologic changes throughout northwestern North America, but the magnitude and direction of changes to low flows remain highly uncertain. Here we study 375 near-natural catchments, across rainfall-dominated, hybrid, snowmelt-dominated, and glacial regimes throughout the habitat range of Pacific Salmon from California to Alaska. Annual minimum summer discharge has decreased in most catchments; rainfall-dominated and hybrid catchments, which predominate in coastal watersheds and in the southern half of the range, have seen the most severe declines. We predict low flows using linear regression models which significantly outperform existing process-based models. We hindcast low flows back to 1900 and project changes to 2100 under four emissions scenarios. Low flows have historically been driven primarily by summer precipitation and moderately influenced by winter snow accumulation and summer temperature. However, we find that future changes will likely be driven by temperature because the magnitude of projected heating is large compared to the historical variability of temperature. Some further declines in low flows are probably inevitable in rainfall-dominated and hybrid catchments: under a low-emissions scenario, low flows will continue to decline to mid-century but then stabilize. Under a high-emissions scenario, 1-in-50-year low flows could occur almost every summer in rainfall and hybrid catchments. Bold climate action and mitigation strategies are urgently required to safeguard these habitats.
511. Kenyon and Jost (2024) Behind the curtain: Characterizing the Nisqually Watershed of MORA as a means to explore the use of non-contact data sources in mountain hydrology
     Impacts from a changing climate are affecting the hydrology, geomorphology, and overall variability of rivers around the world. Upland watersheds are proving to be especially prone to these effects. Mountainous rivers are experiencing significant shifts in precipitation patterns and the storage of snow and ice in source areas, resulting in stark changes to hydrologic variability, sediment transport, and fluvial morphodynamics. Most hydrology methods have been developed for use in rivers with a slope of <0.001 m/m, and the advancement of knowledge relevant to steeper rivers with has followed slowly in comparison. This research aims to address gaps in mountain hydrology associated with the measurement of discharge and bedload sediment transport in mountain rivers with a slope ≥0.02 m/m, seeking means to improve our ability to observe hydrologic trends and morphodynamics. Containing widely distributed low-resilience infrastructure, significant increases to precipitation intensities, and glacial recession rates greater than 0.1 m/day, the Nisqually River within Mount Rainier National Park (MORA) exemplifies a nexus of modern land management issues driven by climate stressors of the Pacific Northwest. With this study we seek to further characterize observable surface processes in the Nisqually watershed within MORA, and begin considering new methods and frameworks which may enable reliable monitoring of steep mountain rivers. We consider the use of seismic, infrasound, and video analysis data as non-contact methods to measure discharge and sediment transport in steep mountain rivers. The primary non-contact data series can then be supported by remote LiDAR products and Sentinel-1 data to assess changes in the source areas and their potential impacts on observable behaviors. Initial data shows observable signals in the seismic/infrasound that seem to correlate to both water flow and bedload transport. We hypothesize there will be observable correlations with topography and snowmelt timing seen though remote sensing analysis, but also anticipate site-to-site variability based on substrate and local morphology. Further development of this framework provides MORA with a means to greatly improve it’s capacity to plan for and address engineering concerns related to climate change, and further research topics in mountain hydrology.
510. Garcia and Todd (2024) Evaluating the effect of air temperatures on suspended sediment in the White River, WA
     Glaciated peaks release high sediment loads into the meltwater streams they produce. Meltwater from Emmons Glacier on Mount Rainier flows into the White River, a tributary of the Puyallup River in Washington State. This study analyzes the effects of air temperature on suspended sediment concentrations (SSCs) and turbidity in the White River. Over two 48-hour periods in July 2023, we collected glacial meltwater emerging from the terminus of Emmons Glacier, and monitored water level, air temperature, and turbidity using a pressure transducer, handheld weather station, and a multiparameter probe, respectively. During one 48-hour period, we also collected glacial meltwater ~ five km downstream using an autosampler. The glacial meltwater samples were filtered, and the dried suspended sediments were weighed to determine the average SSC at each sample time. We compared these data with turbidity data from USGS stream gages located approximately 112 km downstream of Emmons Glacier. Our results show that diurnal peak air temperatures coincided with the peak weights of sediment per unit volume at the glacier terminus; the minimum SSCs at the terminus occurred in the morning when air temperatures are cooler. We measured a 70-75 percent increase between diurnal minimum and maximum sediment load. Over the same time period, USGS stream gages capture diurnal peaks in discharge and turbidity indicative of glacial influence, and a lag between peak discharge and peak turbidity. Our results suggest that glacially-derived suspended sediment concentrations in the White River are sensitive to air temperatures, and that glacial change may impact sediment supply to downstream locations.

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The U.S. Geological Survey Cascades Volcano Observatory and the University of Washington Pacific Northwest Seismic Network continue to monitor Washington and Oregon volcanoes closely and will issue additional notifications as warranted.

Website Resources

For images, graphics, and general information on Cascade Range volcanoes: https://www.usgs.gov/observatories/cvo
For seismic information on Oregon and Washington volcanoes: http://www.pnsn.org/volcanoes
For information on USGS volcano alert levels and notifications: https://www.usgs.gov/programs/VHP/volcano-notifications-deliver-situational-information

Jon Major, Scientist-in-Charge, Cascades Volcano Observatory, jjmajor@usgs.gov

General inquiries: vhpweb@usgs.gov