Hillslope seepage erosion, spring sapping, and knickpoint migration : evidence of groundwater sapping Middle Trinity Aquifer, Honey Creek Basin, Comal County, Texas

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dc.contributor.advisorSharp, John Malcolm, Jr., 1944-
dc.creatorWhite, Kristin Miller
dc.date.accessioned2020-12-14T23:47:48Z
dc.date.available2020-12-14T23:47:48Z
dc.date.issued2005
dc.description.abstractGeomorphic features within Honey Creek basin are consistent with formation by spring sapping which is the erosion of soil and rock by groundwater. Geomorphic evidence includes: swallow holes (stream swallets) that pirate spring discharge into the subsurface, groundwater piping and seepage along weathered marly slopes, headward erosion at knickpoints and spring orifices, fracture controls on incised streams, and generation of alluvium from scarp collapse. Erosion pins were used to measure erosion and sediment accumulation on marly slopes. Aerial photograph interpretation, Arcview GIS, 3D Analyst, and Geoorient techniques were used to evaluate the physical hydrogeologic features (potentiometric surface, karst springs, recharge features, knickpoints, and fractures) and their relationship to surface erosion patterns. Honey Creek basin is underlain by interbedded marl and limestone units of the Cretaceous Middle Trinity aquifer. Springs and caves provide a window into subsurface processes, including flow direction along preferential flowpaths and perched water tables. Precipitation affects spring discharge and water table levels in both stratigraphically perched aquifers and deeper aquifers. Upland karst features allow recharge of surface water to focus flow into spring conduits that rapidly discharge into streams following intense precipitation. Spring conduits and upland creeks feed into intermittent tributaries, then into perennial channels of Honey Creek and the Guadalupe River. Perched aquifers focus flow toward intermittent springs, while perennial springs are supported by a deeper regional system. Transmissivity is high within rock units that contain solutionally enlarged fractures and spring conduits. Elsewhere, the transmissivity of limestone and marl is generally low so that preferred flow pathways concentrate spring discharge where hillslope erosion has intersected bedding planes, conduits, and fractures. As springs discharge into local surface water bodies, erosion occurs at the spring orifices causing headward erosion along the pathways. Dominant fracture trends within the basin are generally aligned with the northeast-trending Balcones Fault Zone and a secondary fracture distribution to the northwest. These trends strongly influence spring location and sappingen_US
dc.description.departmentEarth and Planetary Sciencesen_US
dc.format.mediumelectronicen_US
dc.identifier.urihttps://hdl.handle.net/2152/83891
dc.identifier.urihttp://dx.doi.org/10.26153/tsw/10885
dc.language.isoengen_US
dc.relation.ispartofUT Electronic Theses and Dissertationsen_US
dc.rightsCopyright © is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.en_US
dc.rights.restrictionOpenen_US
dc.subjectGroundwateren_US
dc.subjectErosionen_US
dc.subjectHydrogeologyen_US
dc.subjectTexasen_US
dc.subjectComal Countyen_US
dc.titleHillslope seepage erosion, spring sapping, and knickpoint migration : evidence of groundwater sapping Middle Trinity Aquifer, Honey Creek Basin, Comal County, Texasen_US
dc.typeThesisen_US
dc.type.genreThesisen_US
thesis.degree.departmentGeological Sciencesen_US
thesis.degree.disciplineGeological Sciencesen_US
thesis.degree.grantorUniversity of Texas at Austinen_US
thesis.degree.levelMastersen_US
thesis.degree.nameMaster of Science in Geological Sciencesen_US

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