ScholarWorks@UA is University of Alaska's institutional repository created to share research and works by UA faculty, students, and staff.
Communities in Scholarworks@UA
Select a community to browse its collections.
Development of Landslide Warning SystemLandslides cause approximately 25 to 50 deaths and US$1 - 2 billion worth of damage in the United States annually. They can be triggered by humans or by nature. It has been widely recognized that rainfall is one of the major causes of slope instability and failure. Slope remediation and stabilization efforts can be costly. An early warning system is a suitable alternative and can save human lives. In this project, an early warning system was developed for a 40-foot-high cut slope on the island of Hawaii. To achieve the objective, subsurface investigations were performed and undisturbed samples were collected. For the purpose of unsaturated soil testing, new testing apparatuses were developed by modifying the conventional oedometer and direct shear cells. The unsaturated soil was characterized using two separate approaches and, later, the results were discussed and compared. The slope site was instrumented for the measurement of suction, water content, displacement, and precipitation. The collected climatic data along with the calibrated hydraulic parameters were used to build an infiltration-evapotranspiration numerical model. The model estimations were compared with the field measurements and showed good agreement. The verified model was used to determine the pore-water pressure distribution during and after a 500-years return storm. Later, the pore-water pressure distribution was transferred to a slope stability software and used to study the slope stability during and after the storm. Based on a 2D slope stability analysis, the slope can survive the 500-year storm with a factor of safety of 1.20. Instrument threshold values were established for water content sensors and tensiometers using a traffic-light-based trigger criterion.
Resource limitation of autotrophs and heterotrophs in boreal forest headwater streamsIn stream biofilms, autotrophs and heterotrophs are responsible for the majority of in stream nutrient transformations. In boreal forest catchments, discontinuous permafrost can lead to variation in nutrient and energy resources, which can control competition for nutrients between autotrophs and heterotrophs within these biofilms. I was interested in determining what resources control nutrient utilization by autotrophs and heterotrophs in headwater streams in the boreal forest of interior Alaska. I hypothesized that the outcome of competition between autotrophs and heterotrophs for inorganic nutrients would be dependent on the availability of (i) organic carbon, (ii) light, or (iii) inorganic nutrients. To measure resource limitation and competition at both patch and reach scales, I deployed nutrient diffusing substrata and conducted nutrient uptake experiments in streams along a permafrost gradient at the Caribou-Poker Creeks Research Watershed in interior Alaska. At the patch scale, autotrophs were light and nutrient limited, whereas heterotrophs were carbon and nutrient limited, and at the reach scale, light had the largest influence on nutrient uptake. Heterotrophs exhibited a larger response to nutrient enrichment when stream ambient carbon stocks were more bioavailable. Autotrophic biomass and productivity was suppressed when labile carbon was available to heterotrophs, suggesting that heterotrophs outcompete autotrophs for nutrients when a labile carbon source is introduced. The positive responses to nutrient and carbon additions suggest that the hypothesized increased nutrient and carbon exports into fluvial networks with permafrost degradation will impact biofilm structure and function, with the potential to influence nutrient export and stream ecosystem function downstream.
Quliriuralta (Lets keep telling stories): pace model with traditional Yup'ik storytelling in a second grade dual language classroomThis research was conducted in a setting where the students are losing their Indigenous language. It is centered around the retention and revitalization of the Yugtun language. The goal of the research was to gain insights into how second graders in a dual language enrichment school constructed meaning and focus on form in their classroom. The instructional model employed as part of this investigation is the PACE Model, which is a story-based approach to teaching grammar through focus on form with an emphasis on meaning making. The model is consistent with Indigenous oral storytelling, cultural values, traditions and expectations. The study involves myself and fourteen second graders in Napaskiak, Alaska. ZJW Memorial School is one of 28 schools in the Lower Kuskokwim School District. Of these fourteen students, only one spoke Yugtun as his first language. The others were immersed into Yugtun as a second language. I implemented the PACE approach over the course of 25 days. Data was gathered through field notes, student artifacts, video and audio recordings. The data reveals that meaning making and building background knowledge can be a challenge for both teacher and students. It also reveals that the teacher should be implementing multimodal approaches to build comprehensible input so that students may produce output in the target language.
Effects of wind energy utilization on long-run fuel consumption in remote Alaska microgridsThis paper presents an empirical analysis of the long-run reduction in diesel fuel consumption driven by wind energy utilization in remote Alaska electrical grids. Models control for other fuel consumption determinants including customer base and transmission and distribution system efficiency. Fourteen rural communities that integrated wind energy into their diesel powered electrical grids are analyzed within a dynamic panel framework using monthly utility data spanning sixteen years, from 2001 to 2017. An auto-regressive distributed lag approach is taken to address cointegration and presence of a unit root in the data. Long-run parameters are estimated for the full dataset as well as for four sub-samples to compare impacts on microgrids with high and low average renewable utilization and with large and small customer bases. Results indicate that fuel consumption is reduced by an estimated 68 gallons on average for each one percent increase in wind energy penetration on the electricity grid. Beyond 30% average penetration, however, additional wind energy generation leads to increased fuel consumption as turbine curtailment methods must be employed to maintain grid stability, indicating that this is a fuel-offset constraint point in low and medium penetration wind-diesel hybrid systems. High penetration-capable wind-diesel systems with energy storage capabilities may allow utilities to increase utilization rates beyond this threshold to capture additional fuel savings and carbon emissions offset.
Regional distribution, life history, and morphometry of spawning stage Capelin Mallotus villosusCapelin Mallotus villosus is a forage fish that is integral to many Arctic and subarctic marine food webs, but is less thoroughly studied outside the Atlantic Ocean. The goal of this research was to study spawning Capelin in data-poor areas, particularly in waters off the coast of Alaska and the western Canadian Arctic, to enrich baseline data and allude to intraspecies diversity. Chapter one examined the distribution and life history of spawning Capelin in Norton Sound, Alaska, by conducting aerial surveys, collecting sediment samples to characterize beach spawning habitats, and identifying biological attributes of spawners (e.g., body size, age, fecundity, etc.). Chapter two used a geometric morphometric approach (i.e., relative warps) and multiple statistical techniques (i.e., relative warp analysis, Procrustes analysis of variance, estimates of morphological disparity, and canonical variates analysis) to differentiate among and within putative populations of spawning Capelin in the western Canadian Arctic, Newfoundland, Canada, and Alaska. Spawning Capelin in Norton Sound portrayed similar behaviors, occupied similar beach habitats, and encompassed a similar range in biological attributes as fish observed in other regions throughout this species' geographic distribution. However, average spawner body size, age, fecundity, and morphometry differed among regions. These results suggest that Capelin exhibit some similarities in spawning behavior and habitat use across their geographic distribution, but may exhibit population-specific differences in biological attributes among and within regions.