Theses and Dissertations at Montana State University (MSU)
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Item Spatio-temporal analysis of large magnitude avalanches using dendrochronology(Montana State University - Bozeman, College of Letters & Science, 2020) Peitzsch, Erich Hans; Chairperson, Graduate Committee: Jordy Hendrikx; Jordy Hendrikx, Daniel K. Stahle, Gregory T. Pederson, Karl W. Birkeland and Daniel B. Fagre were co-authors of the article, 'A regional spatio-temporal analysis of large magnitude snow avalanches using tree rings' submitted to the journal 'Natural hazards and Earth systems sciences' which is contained within this dissertation.; Gregory T. Pederson, Jordy Hendrikx, Karl W. Birkeland and Daniel B. Fagre were co-authors of the article, 'Trends in regional large magnitude snow avalanche occurrence and associated climate patterns in the U.S. northern Rocky Mountains' submitted to the journal 'Journal of climate' which is contained within this dissertation.; Chelsea Martin-Mikle, Jordy Hendrikx, Gregory T. Pederson, Karl W. Birkeland and Daniel B. Fagre were co-authors of the article, 'Vegetation characterization in avalanche paths using LIDAR and satellite imagery' submitted to the journal 'Arctic, antarctic, and alpine research' which is contained within this dissertation.Snow avalanches are a natural hazard to humans and infrastructure as well as an important landscape disturbance affecting mountain ecosystems. In many mountainous regions, records of avalanche frequency and magnitude are sparse or non-existent. Inferring historic avalanche patterns to improve forecasting and understanding requires the use of dendrochronological methods. In this dissertation, we examine a regional tree-ring derived large magnitude avalanche dataset from northwest Montana in the northern Rocky Mountains, USA, to produce avalanche chronologies at three distinct scales (path, sub-region, and region), assess seasonal climate drivers of years with large magnitude avalanche occurrence on a regional scale, and characterize vegetation in select avalanche paths. By implementing a strategic spatial sampling design and collecting a large dataset of tree-ring samples, we: (1) assessed scaling in the context of a regional avalanche chronology, reconstructed avalanche chronologies for 12 avalanche paths in four subregions, and examined the effects of two methods of sampling indexing on the resultant avalanche chronology; (2) identified specific climate drivers of large magnitude avalanche years across a region and identified trends in avalanche year probability through time; and (3) tested the feasibility of using remote sensing products to quantify vegetation types in avalanche paths and characterized the vegetation composition based on return periods within specific avalanche paths. This dissertation is organized into 3 key chapters/manuscripts (Chapters 2, 3, and 4) and two supporting chapters (Chapters 1 and 5) that address the problem of assessing large magnitude avalanche frequency at various spatio-temporal scales using a tree-ring dataset. The results contribute toward a better understanding of reconstructing regional avalanche chronologies, a more accurate assessment of avalanche-climate relationships, and improved methods to characterize vegetation characteristics within avalanche path return periods. This work has applications for regions with sparse avalanche records.Item Tree-ring reconstructed streamflow and drought history for the Bighorn River Basin, Wyoming(Montana State University - Bozeman, College of Letters & Science, 2011) Swindell, Bryan Cameron; Chairperson, Graduate Committee: Cathy WhitlockPredictions made by climate models suggest that in the coming decades the western United States will experience warmer temperatures, as well as changes in streamflow patterns. To better understand how climatic variability affects water resources and to critique current water-supply assumptions, water-resource management can benefit from proxy-based paleoclimatic information. Instrumental records of precipitation, streamflow, and snowpack are typically less than 100 years long and usually only capture a subset of the full range of hydrologic variability possible in a given watershed. This study presents water-year streamflow reconstructions for six gages in the Bighorn River Basin in Wyoming and Montana. The reconstructions are based on tree-ring data from various locations in the Northern Rocky Mountain region. The streamflow reconstructions are between 500 and 800 years long. Calibration models between the tree-ring data and the gage record explain up to 60% of the variation in gaged streamflow. Analysis of the reconstructions indicates that the 20th century was relatively wet compared with previous centuries, and recent droughts were matched or exceeded (in duration and magnitude) many times during the last 800 years. Pre-instrumental droughts also show strong spatial coherence across the entire Bighorn River watershed. These reconstructions can be used to develop more-robust water-management plans that take into account a broader range of conditions than those presented by gage records alone.