Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Hydrologic response to channel reconfiguration on Silver Bow Creek : science to inform the restoration process(Montana State University - Bozeman, College of Agriculture, 2010) Kurt-Mason, Seth James; Chairperson, Graduate Committee: Brian L. McGlynn; Geoffrey Poole (co-chair)Hydrologic residence time in streams is rarely considered as a response variable for assessing restoration design strategies. However, residence time is a useful index of hydrologic controls on ecosystem processes that may facilitate or limit the achievement of project goals. Interactions between the physical structure of streambeds and the patterns of flow through the channel determine hydrologic residence time and largely control solute transport and exchange among the various physical and biological components of the stream ecosystem. The influence of reach-scale channel reconfiguration on these complex interactions are not well characterized despite well-documented linkages between individual channel features, hydrologic retention, water quality, and in-stream habitat quality. This study documented changes in solute transport and variation in channel water velocity prior to and immediately following large-scale channel realignment along Silver Bow Creek in southwestern Montana. Channel restoration increased water residence time in the channel by increasing sinuosity, decreasing channel slope, and introducing frequent slow-moving pools. However, channel realignment yielded a reduction in the fine-scale variation in streambed topography. Therefore, post-realignment channel water velocities were more uniform, yielding a reduction in transient storage within the system, which could offset some of the beneficial effects of slower advective velocities. Restoration actions may be more effective at recovering normative hydrologic function if planning and design efforts consider the hydrologic effects and ecological benefits of fine-scale topographic variation and the bio-geomorphic processes that create and maintain such fine-scale variation over time.Item Hydrologic connectivity between landscapes and streams : transferring reach and plot scale understanding to the catchment scale(Montana State University - Bozeman, College of Agriculture, 2010) Jencso, Kelsey Graham; Chairperson, Graduate Committee: Brian L. McGlynn.; Brian L. McGlynn, Michael N. Gooseff, Steven M. Wondzell, Kenneth E. Bencala and Lucy A. Marshall were co-authors of the article, 'Hydrologic connectivity between landscapes and streams: transferring reach- and plot-scale understanding to the catchment scale' in the journal 'Water resources research' which is contained within this thesis.; Brian L. McGlynn, Michael N. Gooseff, Kenneth E. Bencala and Steven M. Wondzell were co-authors of the article, 'Hillslope hydrologic connectivity controls riparian groundwater turnover: implications of catchment structure for riparian buffering and stream water sources' in the journal 'Water resources research' which is contained within this thesis.; Vincent J. Pacific and Brian L. McGlynn were co-authors of the article, 'Variable flushing mechanisms and landscape structure control stream DOC export during snowmelt in a set of nested catchments' in the journal 'Biogeochemistry' which is contained within this thesis.; Brian L. McGlynn and Lucy A. Marshall were co-authors of the article, 'Hierarchical controls on runoff generation: topographically driven hydrologic connectivity, vegetation, and geology' in the journal 'Water resources research' which is contained within this thesis.; Thomas J. Grabs, Brian L. McGlynn, and Jan Seibert were co-authors of the article, 'Calculating terrain indices along streams - a new method for separating stream sides' in the journal 'Water resources research' which is contained within this thesis.Transferring plot and reach scale hydrologic understanding to the catchment scale and elucidating the link between catchment structure and runoff and solute response remains a challenge. To address this challenge, I pursued the following questions as part of this dissertation: How do spatiotemporal distributions of hillslope-riparian-stream (HRS) hydrologic connectivity influence whole catchment hydrologic dynamics and what are the implications of this for stream biogeochemistry? What are the implications of catchment structure for riparian buffering and streamflow source water composition? What are the hierarchical controls on hydrologic connectivity and catchment runoff dynamics across 11 diverse headwater catchments and across flow states? I addressed these questions through detailed hydrometric monitoring and analysis (160 recording wells across 24 HRS transects and stream discharge across 11 catchments), tracer sampling and analysis (groundwater, soil water, and stream water sampling of major ions, specific conductance and dissolved organic carbon (DOC)), and newly developed digital landscape and terrain analyses. I installed this unprecedented network of instrumentation to address these questions across 11 adjacent and nested catchments within the Tenderfoot Creek Experimental Forest (TCEF), Rocky Mountains, MT. I determined that 1) hillslope topography, specifically upslope accumulated area (UAA), was the first order control on the duration of transient water table connectivity observed across HRS landscape positions; 2) the intersection of HRS connectivity with riparian area extents determined the degree of riparian groundwater turnover, riparian buffering of upslope water, and the magnitude of DOC transport to streams; 3) 11 catchments' stream network hydrologic connectivity duration curves were highly correlated to streamflow duration curves and the variable slopes of these relationships were explained by vegetation, geology, and within catchment distributions flowpath length and gradient ratios. This dissertation consists of five key chapters / manuscripts that address how landscape structure/organization within and across catchments can control the timing and magnitude of water and solutes observed at catchment outlets.