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.
Results
Showing 1 to 20 of 20 for “"KARST AQUIFERS"”.
-
Analyzing a 10-Year Cave Drip Record in James Cave, Virginia: Implications for Storage and Recharge in Shallow Appalachian Karst Systems
Karst aquifers, characterized by soluble rocks such as limestone and dolostone, provide drinking water to 20-25% of the world's population and are thus critical global water sources. However, recent work suggests that rapid alteration of karst aquifers due to the impact of climate change on …
-
ΑΣΤΑΘΗΣ ΡΟΗ ΣΕ ΚΑΡΣΤΙΚΑ ΥΔΡΟΦΟΡΑ ΣΤΡΩΜΑΤΑ ΜΕ ΤΗ ΜΕΘΟΔΟ ΤΩΝ ΠΕΠΕΡΑΣΜΕΝΩΝ ΣΤΟΙΧΕΙΩΝ
THE GROUNDWATER FLOW IN A CONFINED KARST AQUIFER IS STUDIED BY THE MODEL OF DOUBLE POROSITY. THIS IS A CONTINUOUS MODEL BUT IT TAKES INTO ACCOUNT THE HETEROGENEITY OF POROUS MEDIA. IT IS ALSO ASSUMED THAT IN KARST AQUIFERS THE FLOW CAN BE BEYOND THE UPPER LIMIT OF THE VALIDITY OF DARCY'S LAW. THE …
-
Analysis of Hydrologic and Geochemical Time Series Data at James Cave, Virginia: Implications for Epikarst Influence on Recharge
Karst aquifers are productive groundwater systems around the world, supplying approximately 25% of the world's drinking water. However, they are highly vulnerable to contamination due to rapid groundwater transit in the transmission zone (KWI 2006). The epikarst, also known as the subcutaneous …
-
Effects of Supraseasonal Drought on Karst Aquatic Communities of the Edwards Plateau
… through 2024, streamflow from spring outflows of karst aquifers were sufficient to provide flowing water habitats in the headwater reaches, upper mainstem, and one of the tributaries. Farther downstream in the mainstem, stream flows became subsurface and reemerged periodically to provide surface …
-
A Quantitative Analysis of Interstitial Fluid-Chemistry and Limestone Dissolution Rates Within the Clastic Sediment of a Karst Aquifer Conduit, Mammoth Cave, Kentucky
<p>Many active stream conduits within karst aquifers transport and deposit non-carbonate, clastic sediment. However, little is known about how these sediments impact conduit development and enlargement rates. For example, can dissolution take place at the sediment/bedrock interface beneath a …
-
Epikarst control on flow and storage at James Cave, VA: an analog for water resource characterization in Shenandoah Valley karst
Karst aquifers host significant water supplies but are easily contaminated because highly conductive inlets can rapidly transmit water to depth. The epikarst, which is the region of vegetation, soil, and weathered bedrock above karst aquifers, is a critical zone as it regulates the quantity and …
-
Modeling karst aquifer response to rainfall
… conductivity and potential gradient in a karst aquifer system. Rainfall excess in the form of potential energy from sinkhole sub-basins is input to element nodes and routed through a one-dimensional finite-element mesh to the karst spring represented by the last node in the finite element …
-
Development of hydrogel tracer beads and comparative tracer tests to better understand contaminant fate and transport in karst systems
Karst aquifers can be highly susceptible to contamination due to a close connection to the land surface, lack of filtration through a soil zone, and rapid transmission along solutionally-enhanced flowpaths. These factors also allow for aquifer contamination by direct injection of immiscible organic …
-
Agricultural Contaminant Source and Transport in a Karst Groundwater Basin
… land use in areas that are located in karst groundwater basins negatively impact groundwater quality because karst terrains provide multiple, direct hydrologic connections from the surface into karst aquifers. The connections and rapid velocities associated with surface and subsurface …
-
Spring Studies and A Decision-Making Process to Guide Groundwater Contamination Prevention in an Agricultural Karst Basin
… major health and environmental issue in karst aquifers because of rapid surface water to groundwater connections and conduit-dominated flow that may allow contaminants to move great distances from their source in a very short amount of time. Agricultural contaminants are a significant …
-
Investigation of the Flow and Fate of Nitrate in Epikarst at the Savoy Experimental Watershed, Northwest Arkansas
<p>Many karst aquifers are at high risk of nitrate contamination due to a combination of vulnerable geology characterized by thin soils and conduit flow, and excess inputs of nutrients from animal feeding operations. One zone that is present in many karst regions and could play an important role in …
-
Determining the Sustainability of Coal Mine Cavity Discharge as a Drinking Water Source
… to the extremely heterogeneous system seen in karst landscapes. Thus, techniques common to karst phenomenon were used to analyze the spring hydrograph. A spring recession analysis was performed upon five storm recessions, and the coefficients for each recession compared and discussed in light …
-
Cave Development in Strata of Ordovician-and Silurian-Devonian-Age in Highland County, Virginia
… that branchwork cave patterns dominate most karst aquifers by frequency and total cave length, fissure-type caves are the most frequent pattern in Highland County and maze network caves are the most predominant pattern by total cave length. Fissure-type caves tend to be very short with most …
-
Assessment and Conceptualization of Groundwater Flow in the Edwards Aquifer Through the Knippa Gap in Uvalde County, Texas
… Edwards aquifer is one of the major regional karst aquifers in the United States, with an average withdrawal of 950 million liters per day (L/d). This investigation focuses on the connection between the Uvalde pool and the San Antonio pool of the Edwards aquifer, known as the Knippa Gap, west …
-
Application of Morphometric Relationships to Active Flow Networks Within the Mammoth Cave Watershed
… in applying these quantitative descriptors to karst flow systems due to the lack of sufficiently complete data and inadequate technology for processing the large, complex data sets. However, as a result of four decades of investigation, an abundance of data now exists for the Mammoth Cave …
-
Modification of the SWAT Model to Simulate Hydrologic Processes in a Karst-influenced Watershed
In the United States, karst ecosystems cover approximately 20 percent of the country and karst aquifers provide 40 percent of the water used for drinking. In karst-influenced watersheds, karst features such as sinkholes and sinking streams act as rapid pathways for carrying water and pollutants …
-
Analysis of Effects of Urbanization on Spring Geochemistry and Sediment for a Karst Aquifer in Valley Creek Basin, Chester County, Pennsylvania
… County, southeastern Pennsylvania, is an urban karst system. Four springs within the Elbrook Formation and two springs in the Ledger Dolomite have been monitored for suspended sediment, baseflow water chemistry, and storm response. Data from previous studies at two rural sites, Nolte in …
-
Groundwater of the North-Western Kalahari, Namibia
… data. The western and south-western secondary aquifers within rocks of the Damara Sequence, the Otavi Mountain karst aquifers of the Tsumeb and Abenab subgroups as well as the Waterberg Etjo sandstone aquifer represent the major hydrochemical groups. Ca/Mg and Sr/Ca ratios allowed to trace the …
-
Investigating Telogenetic Karst Aquifer Processes and Evolution in South-Central Kentucky, U.S., Using High-Resolution Storm Hydrology and Geochemistry Monitoring
… hydrological and geochemical characteristics of karst aquifers in different settings; however, telogenetic karst aquifer processes remain poorly understood. In south-central Kentucky, the iconic Lost River Cave and Valley represents a large, complex telogenetic karst drainage basin with a series …
-
Organic Matter Dynamics and Trophic Structure in Karst Groundwater
In this study of energy pathways in karst groundwater the first chapter examines spatial and temporal patterns of bacterial density and activity in the Dorvan-Cleyzieu karst aquifer, France. During baseflow, bacterial density and activity in the water column was similar in upper and lower zones of …