MAPPING PREFERENTIAL FLOW PATHWAYS IN A RIPARIAN WETLAND USING GROUND-PENETRATING RADAR

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dc.contributor.advisorMcIntosh, Marlaen_US
dc.contributor.authorGormally, Kevin Hillen_US
dc.contributor.departmentMarine-Estuarine-Environmental Sciencesen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2009-07-02T06:07:53Z
dc.date.available2009-07-02T06:07:53Z
dc.date.issued2009en_US
dc.description.abstractPreferential flow of water through channels in the soil has been implicated as a vehicle for groundwater and surface water contamination in forested riparian wetland buffers. Water conducted through these by-pass channels can circumvent interaction with wetland biota, biomass, and soils, thereby reducing the buffering capacity of the riparian strips for adsorption and uptake of excess nutrient loads from neighboring agricultural fields and urbanized lands. Models of riparian function need to account for preferential flow to accurately estimate nutrient flux to stream channels, but there are currently no methods for determining the form and prevalence of these pathways outside of extensive destructive sampling. This research developed, tested, and validated a new application of non-invasive ground-penetrating radar technology (GPR) for mapping the three-dimensional structure of near-surface (0-1 m) lateral preferential flow channels. Manual and automated detection methodologies were created for analyzing GPR scan data to locate the channels in the subsurface. The accuracy of the methodologies was assessed in two field test plots with buried PVC pipes simulating the riparian channels. The manual methodology had a 0% Type I error rate and 8% Type II error rate; the automated version had a <1% Type I error rate and 29% Type II error rate. An automated mapping algorithm was also created to reconstruct channel geometries from the scan data detections. The algorithm was shown to robustly track the connectivity of PVC pipe segments arranged in a branching structure hypothesized to exist in the riparian soils. These methods and algorithms were then applied at a riparian wetland study site at USDA Beltsville Agricultural Research Center in Beltsville, MD. The predicted structure of preferential flow channels in the wetland was validated by transmission of tracer dye through the study site and ground truth generated from soil core samples (92% accurate). These GPR tools will enable researchers to efficiently and effectively characterize lateral preferential flow without negatively impacting environmentally sensitive wetland areas. Scientists can now directly study these flow mechanisms to investigate the effects of by-pass pathways on nutrient fate in riparian buffers and the interactions of preferential flow with plant and animal systems.en_US
dc.format.extent8411952 bytes
dc.format.mimetypeapplication/pdf
dc.identifier.urihttp://hdl.handle.net/1903/9267
dc.language.isoen_US
dc.subject.pqcontrolledEnvironmental Sciencesen_US
dc.subject.pqcontrolledGeophysicsen_US
dc.subject.pqcontrolledAgriculture, Soil Scienceen_US
dc.subject.pquncontrolledGPRen_US
dc.subject.pquncontrolledmacroporeen_US
dc.subject.pquncontrolledmapping algorithmen_US
dc.subject.pquncontrolledOPE3en_US
dc.subject.pquncontrolledpreferential flowen_US
dc.subject.pquncontrolledriparian wetlanden_US
dc.titleMAPPING PREFERENTIAL FLOW PATHWAYS IN A RIPARIAN WETLAND USING GROUND-PENETRATING RADARen_US
dc.typeDissertationen_US

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