Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 22 for “"Hyporheic Exchange"”.
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Assessment of Hyporheic Exchange at In-stream Restoration Structures on Savage River, Garrett County, Maryland
… that in-stream restoration structures alter hyporheic exchange dynamics in restored channels; this study assessed hyporheic exchange at a recently constructed stream reach, including the effects of in-stream restoration structures. Hydrometric and thermal data were collected in the streambed …
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Comparing Reach Scale Hyporheic Exchange and Denitrification Induced by Instream Restoration Structures and Natural Streambed Morphology
… may be attempted. One strategy is increasing hyporheic zone flow at baseflow by addition of instream structures. The hyporheic zone can be an area of increased biogeochemical activity, with potential enhancement of reactions such as denitrification. However, the comparative effects of various …
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Experimental Evaluation of Three Backward Transit Time Distributions (bTTD) for Solute Storage and Release During Hyporheic Exchange
Hyporheic exchange in streams supports many important ecosystem services but can also contribute to legacy pollution, by trapping less reactive contaminants in streambed sediments that are then slowly released back to the stream over time. In this study we evaluated three different analytical …
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Effect of Urbanization on the Hyporheic Zone: Lessons from the Virginia Piedmont
… are a cause of increasing concern. The hyporheic zone is an important part of stream ecosystems, and here we focus on the effect of urbanization on the hyporheic zone from ten first-to-second-order streams within the Virginia Piedmont. We use sediment hydraulic conductivity and stream …
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Flow and reactive transport modeling at the stream-groundwater interface
… these processes by increased water and solute exchange across this interface, denoted as hyporheic exchange. This thesis investigates the influence of hydrological and morphological factors on hyporheic water and solute exchange as well as redox-reactions in fluvial streambed structures on the …
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Cumulative Impacts of Watershed-Scale Hyporheic Stream Restoration on Nitrate Loading to Downstream Waterbodies
… of the eastern USA. We simulated restoration of hyporheic exchange as one increasingly popular technique that receives dissolved nitrate-nitrogen (NO3--N) mitigation credit under the Chesapeake Bay TMDL. We populated the model with hyporheic exchange (0.3% of surface flow per hyporheic-exchange …
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Hyporheic flow in a mountainous riverine system
Investigation into the effects of beaver dams on hyporheic exchange in peat dominated mountainous streams is needed to better understand stream-floodplain connections and improve our overall conceptual model of water storage and flow through riverine valleys. The objective of this study was to …
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A three dimension hyporheic model of the River Bure: Understanding the nutrient dynamics and the role of streambed heterogeneity
The hyporheic zone is often defined as the zone where mixing of surface water and groundwater occurs in shallow sediments beneath and adjacent to rivers. This mixing contributes to create unique biogeochemical conditions that may attenuate contaminants from either upstream surface water or …
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Abundance, Distribution, and Geometry of Naturally Occurring Macropores in Stream Banks
… banks and have the potential to enhance the exchange of water and solutes between the channel and riparian groundwater, yet the geographic distribution of bank macropores is unknown. Here we determined the abundance, distribution, and geometry of naturally occurring surface-connected …
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Preferential and Non-Darcy Flows in the Hyporheic Zone: Surface Water-Groundwater Hydraulics and Effects on Stream Functions
… the dominance of hydraulic conductivity (K) on hyporheic hydraulics and implications to hyporheic zone functions through a series of modeling studies and field experiments. Computational Fluid Dynamics (CFD) software was used to model the effect of varying K on weir-induced hyporheic exchange …
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In the Zone: the Effects of Soil Pipes and Dunes on Hyporheic and Riparian Zone Hydraulics and Biogeochemistry
… pollutants in stream corridors. The focus is hyporheic zones which form the interface between surface water and groundwater below and adjacent to stream channels, and riparian zones which form the interface between channels and adjacent uplands, both of which can attenuate pollutants. In this …
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Modeling temporal and spatial variations in dissolved oxygen in Amite River
… VART-DO model is the capability of simulating DO exchange across the water-sediment interface through the hyporheic exchange mechanism in addition to the air-water exchange. Simulation results from VART-DO model revealed that hyporheic exchange can reduce K2 by 30% while longitudinal dispersion …
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From grain to floodplain: evaluating heterogeneity of floodplain hydrostratigraphy using sedimentology, geophysics, and remote sensing
… such as groundwater flow and transport and hyporheic exchange. This study, conducted in the East River Basin, Colorado, USA, combines point-, meander-, and floodplain-scale data to explore the importance of detailed field studies and physical representation of alluvial aquifers. We combine …
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Quantifying groundwater-surface water interactions to improve the outcomes of human activities
… surface water in streams and groundwater in hyporheic zones and shallow fluvial aquifers, and how human beings influence these interactions and are influenced by them. The three chapters of this dissertation span scales from cm to km and locations from Upstate New York to the Peruvian Andes, …
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Complementary Effects of In-Stream Structures and Inset Floodplains on Solute Retention
… retention in off channel storage zones such as hyporheic zones and floodplains is typically necessary for significant reaction to occur. �Yet the effects of two common restoration techniques, in stream structures and inset floodplains, on solute retention have not been rigorously compared. …
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Hydrologic Characteristics of Summer Stream Temperatures in Little Creek and Scotts Creek at the Swanton Pacific Ranch
… stream water storage, and heat budget exchanges. Stream temperature, hydrologic, climatic, and channel morphological data were collected on two, approximately 800 m stream reaches on Little Creek and Scotts Creek located in mixed coast redwood and Douglas-fir forests of Santa Cruz …
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Turbulent interactions between stream flow and near-subsurface flow: a laboratory approach using particle image velocimetry and refractive index matching
… streamwise momentum due to vertical momentum exchange by turbulence. In the pore spaces, mean velocities are subhorizontal in direction and 5-10% of the maximum free stream velocity. High Reynolds stresses near the bed, particularly around the crests of spherical roughness elements, suggest …
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Using temperature profiles to investigate the hyporheic zone in an agricultural drainage ditch
… on ground water/surface water interaction and hyporheic zone processes in natural rivers and streams. Research into natural systems has revealed significant ground water/surface water interaction and a complex variability that depends primarily on surface conditions, subsurface composition, and …
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Improved predictions of contaminant transport in rivers
… model that accounts for surface storage and hyporheic exchange as well as for lateral inflow and decay in the main channel and two storage zones. Analysis of temporal moments shows that the subsurface storage zone affects the transport even if the transfer coefficient between subsurface …
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Water Quality and Groundwater Discharge in the Halton Region
… of spatiotemporal water quality variability and hyporheic exchange patterns at the watershed scale and optimize regional management of vulnerable streams and natural heritage systems.
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