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Abstract Timing and completeness of freeze‐up on northern rivers impact winter travel and indicate responses to climate change. Open‐water zones (OWZs) within ice‐covered rivers are hazardous and may be increasing in extent and persistence. To better understand the distribution, variability, and mechanisms of OWZs, we selected nine reaches totaling 380 river‐km for remote sensing analysis and field studies in western Alaska. We initially identified 48 OWZs from November 2022 optical imagery, inventoried their persistence into late winter and interannual consistency over previous years, and at a subset measured ice thickness, water depth and velocity, and physicochemistry. The most consistent locations of OWZ formation occurred below sharp bends and channel constrictions, whereas locations associated with river bars and eroding banks were more transient. Of 359 OWZs identified in early winter over 6 years, 8% persisted into late winter―all on the Yukon River mainstem. Although several OWZs were in locations where we anticipated groundwater influence, we found no field data indication of groundwater upwelling. Observations of jumble ice upstream of many OWZs led us to examine freeze‐up ice jam locations in optical imagery, which showed strong correspondence to downstream OWZs. We hypothesize that reaches downstream of ice jams are much slower to freeze‐over due to restricted ice transport and high turbulence caused by channel form and ice‐affected hydraulics. Future work should focus on evaluation of this and other competing hypothesis at both reach and river network scales to predict OWZ locations and occurrence relative to other processes affecting river freeze‐up in northern climates. 

Abstract Ice formation is generally considered to exclude many particles and most solutes and thus be relatively pure compared to ambient waters. Because river ice forms by a combination of thermal and mechanical processes, some level of sediment entrainment in the ice column is likely, though reports of sediment in river ice are limited. We observed high and sporadic levels of silt and sand in ice of the Kuskokwim and Tanana rivers (Alaska, the United States) during routine field studies. These observations led us to make a more comprehensive survey of sediment entrainment in river ice of the Kuskokwim and Yukon rivers and several of their tributaries. We collected and subsampled 48 ice cores from 19 different river locations in March 2023, which included concurrent measurements of water turbidity, velocity, and depth. Approximately 60% of cores contained detectable levels of sediment, averaging 438 mg/L with median concentrations exceeding 1000 mg/L in three cores from the Yukon and Kuskokwim main stems. Many cores had even higher concentrations at certain intervals, with seven cores having subsamples exceeding 2000 mg/L; these were often located in the middle or lower portion of the ice column. Jumble ice, formed mechanically by frazil‐pan jamming during freeze‐up, was generally the best predictor of higher sediment entrainment, and these locations often had higher under‐ice velocities and depths. Our observation of high and widespread sediment entrainment in northern river ice, particularly in jumble‐ice fields, may have implications for sediment transport regimes, ice strength and transportation safety, and how rivers break up in the springtime. 

This study introduces a new automated system that blends multi-satellite information and citizen science data for reliable and timely observations of lake and river ice in under-observed northern regions. The system leverages the Google Earth Engine resources to facilitate the analysis and visualization of ice conditions. The adopted approach utilizes a combination of moderate and high-resolution optical data, along with radar observations. The results demonstrate the system’s capability to accurately detect and monitor river ice, particularly during key periods, such as the freeze-up and the breakup. The integration citizen science data showed added values in the validation of remote sensing products, as well as filling gaps whenever satellite observations cannot be collected due to cloud obstruction. Moreover, it was shown that citizen science data can be converted to valuable quantitative information, such as the case of ice thickness, which is very useful when combined with ice extent derived from remote sensing. In this study, citizen science data were employed for the quantitative assessment of the remote sensing product. Obtained results showed a good agreement between the product and observed river status, with a Critical Success Index of 0.82. Notably, the system has shown effectiveness in capturing the spatial and temporal evolution of snow and ice conditions, as evidenced by its application in analyzing specific ice jam events in 2023. The study concludes that the developed system marks a significant advancement in river ice monitoring, combining technological innovation with community engagement. 

Understanding aquatic habitat and water resource responses to rapid and ongoing changes in both climate and land-use provide the basis for monitoring physical processes in ten streams and their watersheds in the northeastern portion of the National Petroleum Reserve in Alaska (NPR-A). Streams selected for monitoring were originally based on planned development in their upstream catchments and to represent reference (undeveloped) conditions. Monitoring periods for each station (up to 15 years) vary according to adaptive management of water resources in response to broader NPR-A management planning as well as alignment with proposed and ongoing monitoring efforts in Arctic Alaska. Stream discharge and water temperature data provide basic information to characterize physical regimes and variability among drainage units with respect to flood hazards, responses to land and permafrost dynamics, and connectivity and suitability of habitat for fish and other aquatic organism. Evaluating potential impacts of petroleum development primarily in the from lake water extraction, roads, and oil drilling and transport infrastructure are also an intended use of the data and reason for maintaining these monitoring stations. These data also support basic scientific studies of several National Science Foundation and U.S. Fish and Wildlife funded projects to characterize and understand the Arctic system. Data collection was primarily supported by the Bureau of Land Management. 

Youth-focused community and citizen science (CCS) is increasingly used to promote science learning and to increase the accessibility of the tools of scientific research among historically marginalized and underserved communities. CCS projects are frequently categorized according to their level of public participation and their distribution of power between professional scientists and participants from collaborative and co-created projects to projects where participants have limited roles within the science process. In this study, we examined how two different CCS models, a contributory design and a co-created design, influenced science self-efficacy and science interest among youth CCS participants. We administered surveys and conducted post-program interviews with youth participation in two different CCS projects in Alaska, the Winterberry Project and Fresh Eyes on Ice, each with a contributory and a co-created model. We found that youth participating in co-created CCS projects reflected more often on their science self-efficacy than did youth in contributory projects. The CCS program model did not influence youths’ science interest, which grew after participating in both contributory and co-created projects. Our findings suggest that when youth have more power and agency to make decisions in the science process, as in co-created projects, they have greater confidence in their abilities to conduct science. Further, participating in CCS projects excites and engages youth in science learning, regardless of the CCS program design. 

Lakes set in arctic permafrost landscapes can be susceptible to rapid drainage and downstream flood generation. Of many thousands of lakes in northern Alaska, hundreds have been identified as having high drainage potential directly to river systems and 18 such drainage events have been documented since 1955. In 2018 we began monitoring a large lake with high drainage potential as part of a long-term hydrological observation network designed to evaluate impacts of land use and climate change. In early June 2022, surface water was observed flowing over a 30-m wide bluff, with active headward erosion of ice-rich permafrost soils apparent by late June. This overflow point breached rapidly in early July, draining almost the entire lake within 12 h and generating a 191 m3/s flood to a downstream creek. Water level and turbidity sensors and time-lapse cameras captured this rapid lake-drainage event at high resolution. A wind-driven surface seiche and warming waters following ice-out helped trigger the initial thermomechanical breach. We estimate at least 600 MT of lake sediment was eroded, mobilized, and transported downstream. A flood wave peaking at 42 m3/s arrived 14 h after the initial breach at a river gauge 9-km downstream. Comparing this event with three other quantified arctic lake-drainage floods suggests that lake surface area coupled with drainage gradient height can predict outburst flood magnitude. Using this relationship we estimated future flood hazards from the 146 lakes in the Arctic Coastal Plain of northern Alaska (ACP) with high drainage potential, of which 20% are expected to generate outburst floods exceeding 100 m3/s to downstream rivers. This fortunate and detailed drainage-event observation adds to a growing body of research on the impact of lakes on arctic hydrology, hazard forecasting in a region with an increasing human footprint, and broader processes of landscape evolution in arctic lowlands.