Theses and Dissertations at Montana State University (MSU)
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Item The effect of watershed structure and climate on streamflow response, hydrologic memory, and runoff source areas(Montana State University - Bozeman, College of Agriculture, 2014) Nippgen, Fabian; Chairperson, Graduate Committee: Jack Brookshire; Brian McGlynn, Lucy Marshall and Ryan Emanuel were co-authors of the article, 'Landscape structure and climate influences on hydrologic response' in the journal 'Water resources research' which is contained within this thesis.; Brian McGlynn, Ryan Emanuel and James Vose were co-authors of the article, 'Watershed memory at the Coweeta Hydrologic Laboratory: the effect of past precipitation and storage on hydrologic response' which is contained within this thesis.; Brian McGlynn and Ryan Emanuel were co-authors of the article, 'The temporal evolution of variable contributing areas' submitted to the journal 'Water resources research' which is contained within this thesis.Watershed-scale hydrology research has long focused on understanding how various feedbacks in the soil-vegetation-atmosphere continuum affect streamflow. With this dissertation I sought to contribute to our understanding of how watershed characteristics (e.g. topography and vegetation) and climate affect various aspects of watershed hydrology, such as streamflow response times, watershed memory, and runoff source areas. Specifically, I was interested in 1) how watershed structure and climate affect inter- and intra-watershed variability in hydrologic response times, 2) how past precipitation and watershed memory affect runoff response on time scales of months to years, and 3) how runoff source areas vary through time. I approached these challenges/questions through a combination of spatially and temporally intensive and extensive observations synthesized as a) application of a simple lumped model to distill complex watershed behavior into comparable metrics across nested watersheds, b) empirical analysis of long-term hydroclimatic data sets to investigate the effect of watershed memory on the hydrologic response of watersheds, and c) the development of a parsimonious but fully distributed hydrologic rainfall-runoff model to characterize the effect of topographically driven lateral water redistribution and water uptake by vegetation on landscape scale hydrologic connectivity. We demonstrated that 1) differences in response times between watersheds were caused by differences in watershed structure while differences in response times between years were a function of maximum snow accumulation; 2) we found strong influences of past precipitation on runoff from monthly to annual time scales; 3) runoff source areas were highly variable over the course of two water years and exhibited hysteretic spatial behavior over the course of the snow melt seasons. This dissertation contributed new hydrologic understanding of how watershed properties (topography, geology, vegetation etc.), climatic variability, and the interactions between them affect hydrologic response at the watershed scale.Item Identifying linkages between aquatic habitat, geomorphology, and land use in Sourdough Creek Watershed(Montana State University - Bozeman, College of Agriculture, 2004) McIlroy, Susan Kay; Chairperson, Graduate Committee: Cliff Montagne.Aquatic systems reflect the geomorphological and land use processes that shape them. System function, structure, and composition are driven by both autogenous and exogenous processes at small- and large-scales. Impacts often act synergistically, increasing the complexity and magnitude of their effects on aquatic systems. To assess these impacts, watershed scale studies are becoming more common, and an integration of research and management is beginning to emerge. Diverse user groups and differing agendas complicate watershed management and restoration, making a collaborative decision-making process imperative. Objectives of this study were to identify linkages between aquatic habitat, geomorphology, and land use in Sourdough Creek Watershed, explore potential land use impacts in the Lower Watershed, and identify a sustainable management plan for the watershed. Specific questions involved identifying potential westslope cutthroat trout reintroduction areas in the Upper Watershed and exploring statistical correlations between six land classes and the response variables of large woody debris and pool length. This study found suitable reintroduction areas as well as identified linkages between predictor variables and LWD and pool length across land classes. Although others have assessed aquatic habitat on a large-scale as well as identified potential management paradigms, this study integrates the two in order to provide a useful document for stakeholders and managers of Sourdough Creek Watershed.Item The application of approximate bayesian computation in the calibration of hydrological models(Montana State University - Bozeman, College of Agriculture, 2014) Brown, Jason John; Chairperson, Graduate Committee: Robert A. Payn; Lucy A. Marshall, Rob A. Payn, and Mark C. Greenwood were co-authors of the article, 'The application of approximate bayesian computation and sequential monte carlo in the calibration of hydrological models' submitted to the journal 'Hydrology and earth system sciences' which is contained within this thesis.There is an increasing need to obtain proper estimates for the uncertainty associated with Conceptual Rainfall-Runoff models and their predictions. Within hydrology, uncertainty analysis is commonly conducted using Bayesian inference or Generalized Likelihood Uncertainty Estimation (GLUE). Bayesian inference is a statistically rigorous method for estimating uncertainty, but it depends upon a formal likelihood function that may not be available. GLUE utilizes a generalized likelihood function that can operate as a proxy for a formal likelihood function. While this allows GLUE to effectively calibrate hydrological models with intractable likelihood functions, the lack of statistical rigor may negatively affect the uncertainty estimations. Approximate Bayesian Computation (ABC) is a family of likelihood-free methods that have been recently introduced for calibrating hydrological models. While these methods are implemented using formal Bayesian inference for assessing uncertainty, they do not require any assumptions regarding the likelihood function. Thus they have the potential flexibility of GLUE with the statistical rigor inherent in Bayesian Inference. The studies presented within this thesis demonstrate the theoretical links between GLUE and ABC. We then assess the efficacy of an implementation of ABC utilizing a Sequential Monte Carlo sampler (ABC-SMC) for calibrating Conceptual Rainfall-Runoff models. Two components of the ABC-SMC algorithm were evaluated. These included three classes of summary statistics used for evaluating model performance and post-processing techniques to adjust the final posterior distributions of the parameters. ABC-SMC was computationally efficient in calibrating a six parameter hydrological model for one synthetic and two real world data sets. Post-processing using local linear regression generated marginal improvements to the posterior distributions. Summary statistics measuring the goodness-of-fit between the observed and predicted hydrographs performed well for the synthetic data where the total uncertainty was low. A composite summary statistic based upon matching both hydrograph and hydrological signatures of a basin were more effective for the real world data sets as total uncertainty increased. The results suggest a properly implemented ABC-SMC algorithm is an effective method for calibrating watershed models and for conducting uncertainty analysis.Item The role of stream network nutrient uptake kinetics and groundwater exchange in modifying the timing, magnitude, and form of watershed export(Montana State University - Bozeman, College of Agriculture, 2012) Covino, Timothy Patrick; Chairperson, Graduate Committee: Brian L. McGlynn.; Brian L. McGlynn and Rebecca A. McNamara were co-authors of the article, 'Tracer additions for spiraling curve characterization (TASCC): quantifying stream nutrient uptake kinetics from ambient to saturation' in the journal 'Limnology and oceanography: methods' which is contained within this thesis.; Brian McGlynn and Rebecca McNamara were co-authors of the article, 'Land use / land cover and scale influences on in-stream nitrogen uptake kinetics' in the journal 'Journal of geophysical research - biogeosciences' which is contained within this thesis.; Brian McGlynn and John Mallard were co-authors of the article, 'Stream-groundwater exchange and hydrologic turnover at the network scale' in the journal 'Water resources research' which is contained within this thesis.; Brian McGlynn and Michelle Baker were co-authors of the article, 'Separating physical and biological nutrient retention and quantifying uptake kinetics from ambient to saturation in successive mountain stream reaches' in the journal 'Journal of geophysical research - biogeosciences' which is contained within this thesis.In this PhD dissertation research we sought to elucidate stream network biological and physical influences on hydrological and biogeochemical signatures observed along stream networks and at watershed outlets. Our research indicates that stream nutrient uptake and groundwater exchange processes can modify inputs from terrestrial sources and influence the timing and signature of watershed fluxes. We determined that stream nutrient uptake followed Michaelis-Menten kinetics across a broad range of systems and that land use / land cover change can alter stream nutrient uptake magnitudes. Additionally, we found that watershed structure and network geometry exerted strong controls over sourcewater contributions and streamwater compositions along stream networks and at watershed outlets. Combined, this PhD research suggests that uptake kinetics and hydrologic turnover exert strong controls over streamwater composition and sourcewater contributions, and that physical and biological contributions to total nutrient retention and the dynamic and concentration dependent nature of biological uptake combine to control solute and nutrient signatures. We suggest accurate assessment of total retention across stream reaches and stream networks requires quantification of physical retention and the concentration dependent nature of biological uptake, understanding necessary to help mitigate the potentially deleterious influences elevated nutrient export can have on downstream ecosystems.Item Spatial and seasonal variability of watershed response to anthropogenic nitrogen loading in a mountainous watershed(Montana State University - Bozeman, College of Agriculture, 2010) Gardner, Kristin Kiara; Chairperson, Graduate Committee: Brian L. McGlynn.; Brian L. McGlynn was a co-author of the article, 'Seasonality in spatial variability and influence of land use/land cover and watershed characteristics on streamwater nitrogen export in a developing watershed in the Rocky Mountain West ' in the journal 'Water resources research' which is contained within this thesis.; Brian L. McGlynn was a co-author of the article, 'A multi-analysis approach to assess the spatio-temporal patterns of watershed response to localized inputs of nitrogen' in the journal 'Water resources research' which is contained within this thesis.; Brian L. McGlynn, and Lucy A. Marshall were co-authors of the article, 'Quantifying watershed sensitivity to spatially variable nitrogen loading and the relative importance of nitrogen retention mechanisms' in the journal 'Water resources research' which is contained within this thesis.Anthropogenic activity has greatly increased watershed export of bioavailable nitrogen. Escalating levels of bioavailable nitrogen can deteriorate aquatic ecosystems by promoting nuisance algae growth, depleting dissolved oxygen levels, altering biotic communities, and expediting eutrophication. Despite these potential detrimental impacts, there is notable lack of understanding of the linkages between anthropogenic nitrogen inputs and the spatial and seasonal heterogeneity of stream network concentrations and watershed nitrogen export. This dissertation research seeks to more accurately define these linkages by investigating the roles of landscape position and spatial distribution of anthropogenic nitrogen inputs on the magnitude and speciation of watershed nitrogen export and retention and how these roles vary seasonally across contrasting landscapes in a 212 km ² mountainous watershed in southwest Montana. Results indicate localized inputs of anthropogenic nitrogen occurring in watershed areas with quick transport times to streams had disproportionate effects on watershed nitrogen export compared to spatially distributed or localized inputs of nitrogen to areas with longer transport times. In lower elevation alluvial streams, these effects varied seasonally and were most evident during the dormant winter season by amplified nitrate peaks, elevated dissolved organic nitrogen:dissolved organic nitrogen (DIN:DON) ratios and lower dissolved organic carbon (DOC):total dissolved nitrogen (DOC:TDN). During the summer growing season, biologic uptake of nitrogen masked anthropogenic influences on watershed nitrogen export; however, endmember mixing analysis of nitrate isotopes revealed significant anthropogenic influence during the growing season, despite low nitrate concentrations and DIN:DON ratios. In contrast, streams draining alpine environments consisting of poorly developed, shallow soils and small riparian areas exhibited yearlong elevated nitrate concentrations compared to other sites, suggesting these areas were highly nitrogen enriched. Watershed modeling revealed the majority of watershed nitrogen retention occurred in the upland environment, most likely from biological uptake or lack of hydrologic connectivity. This work has critical implications for watershed management, which include: 1) developing flexible strategies that address varying landscape characteristics and nitrogen loading patterns across a watershed, 2) avoiding clustering nitrogen loading in areas with quick travel times to surface waters, 3) seasonal monitoring to accurately gauge watershed nitrogen saturation status, and 4) incorporating spatial relationships into streamwater nitrogen models.Item Watershed restoration limitations at the abandoned reclaimed Alta Mine, Jefferson County, MT(Montana State University - Bozeman, College of Agriculture, 2008) Labbe, Richard James; Chairperson, Graduate Committee: Clayton B. Marlow; Timothy R. McDermott (co-chair)Abandoned hardrock metal mines can have an antagonistic effect on soil productivity, vegetation, and water quality. Specifically, abandoned mines that actively generate acidity in soil are phytotoxic due to low pH and increased bioavailability of heavy metals. Arsenic concentrations in mine soils are often elevated, but may not be as mobile as heavy metals at low pH. Acid mine drainage migration from abandoned mines is problematic because it leads to water quality impairments that limit water use for certain activities (i.e. stock watering and irrigation). In this work, a previously reclaimed abandoned lead and silver mine (Alta Mine Jefferson County, MT) was characterized for its persistent impacts on soil, vegetation, and water quality. A progressive monitoring effort linked offsite water quality impacts to deep underground mine workings, shallow ground water, and metalliferous soils found at the Alta mine. Vegetative cover was measured in 16 transects in conjunction with 30 soil pits excavated on the reclaimed site. By regression and analysis of variance, sparse vegetative cover was significantly (p<0.1) linked to pH and acid generation potential. To overcome acidic soil conditions, lime and compost amendments were tested on site. The amendments significantly (p<0.1) neutralized soil acidity; however, a corresponding increase in vegetative cover was not observed. Erosion of the bare unstable slopes caused greater than anticipated seed bank loss that precluded vegetation establishment. The successful establishment of a dense vegetative cover on the abandoned mine could prevent erosion and water quality impacts due to sedimentation. Vegetation may also have minor impacts on landscape sources of arsenic and heavy metals that were identified in the study; but the most significant source of water quality impairment, deep underground mine workings, will persist under any land treatment.Item Stream nitrogen uptake dynamics from ambient to saturation across development gradients, stream network position, and seasons(Montana State University - Bozeman, College of Agriculture, 2010) McNamara, Rebecca Anne; Chairperson, Graduate Committee: Brian L. McGlynn; Wyatt Cross (co-chair)The balance between stream nitrogen (N) loading and retention determines stream network nutrient export dynamics. Nutrient retention can be altered due to changes in hydrology, nutrient loading, and biological community response to increased nutrient availability. We quantified physical and biological contributions to total nutrient retention and determined biological uptake kinetics from ambient to saturation across six stream reaches across the West Fork Gallatin Watershed (a 1st to 4th order, headwater, 240 km² watershed) which has experienced rapid exurban, resort development leading to increased watershed nutrient loading over the last four decades. We conducted 17 stream tracer experiments (constant-rate and instantaneous additions) using both conservative (chloride (Cl)) and biologically active (nitrate (NO 3-N)) tracers across a range of watershed areas (WA), stream discharges, seasons, development intensities, and ambient NO 3-N concentrations, reflecting varying degrees of development and upland nutrient loading (i.e., wastewater effluent). Ambient uptake (U amb) was calculated and Michaelis-Menten kinetic models were used to quantify maximum areal uptake rates (U max) and half-saturation constants (K m) for each experimental reach. In the West Fork Gallatin Watershed, the majority of added NO 3-N was physically retained within stream reaches of smaller WA with decreasing physical retention as WA increased. However, as WA increased, biological retention of added NO 3-N became increasingly important and exceeded physical retention in the two largest watersheds. Further, U amb and U max values increased with greater WA, and U max was greatest in the summer and lowest in the winter. Our results demonstrated that nutrient uptake variability between stream reaches was related to WA, discharge, ambient NO 3-N concentration, and season. Although some streams in the watershed no longer appear to be functioning at pre-development levels, none demonstrated saturation with respect to NO 3-N, yet with continued development and increased loading, nutrient saturation could occur. We suggest that quantifying physical and biological contributions to total retention and determining uptake kinetics from ambient to saturation over space, time, and development intensities can yield new insight into the capacity of stream networks to buffer nutrient loading.Item The role of stream network hydrologic turnover in modifying watershed runoff composition(Montana State University - Bozeman, College of Agriculture, 2012) Mallard, John McDevitt; Chairperson, Graduate Committee: Brian L. McGlynn.Stream networks can attenuate and modify hydrological, biogeochemical, and ecological signals generated in the terrestrial and in-stream portions of watersheds. Stream networks can modify watershed signals through spatially variable stream gains and losses to and from groundwater, described herein as hydrologic turnover. We measured hydrologic gain and loss at the reach scale using conservative tracer experiments throughout the Bull Trout Watershed in the Sawtooth Mountains of central Idaho. These experiments allowed us to track water moving into and out of groundwater from and to stream water. We extended these measured reach scale water balance components to the stream network using observed empirical relationships between 1) accumulated watershed area and stream discharge, and 2) stream discharge and percent discharge lost from the stream. We developed a watershed and stream network-scale model to simulate hydrologic turnover across stream networks to quantify its effects across watershed of varying structure and stream networks of varying geometry. These analyses elucidated the influence of watershed inputs to streams on downstream stream water composition. We determined that the magnitude of contributions to discharge from any upstream watershed input depended on the magnitude of the initial input, but also on the amount of hydrologic turnover downstream along the stream network. Downstream hydrologic turnover was a function of the intersection of watershed structure and stream network geometry. Our results suggest that a distributed representation of hydrologic turnover at the stream network scale is requisite for understanding how the stream network filters and modifies watershed inputs signals observed in streams or watershed outlets.