The United States Forest Service desires to build a 2,700 acre surface water reservoir by constructing a dam to impound water on Oakohay Creek in Smith County, Mississippi. A previous study from 2007 deemed the proposed location based on the hydrologic and geologic characteristics. The reinvestigation study objectives focused on the site’s hydrology and geology. The hydrologic study was accomplished by developing daily water storage models for the proposed reservoir. Archived data from the Southern Regional Climate Center were used in the models. The geologic study evaluated the Glendon Limestone through field surveying, ground penetrating radar, sonic rig drilling, surface water quantity measurements, and surface water quality analysis. A dedicated stream monitoring station was installed along the banks of Oakohay Creek. ArcGIS 9.3.1 and Microsoft Excel were used to support the objectives. Results from the study suggest that the proposed site location is suitable for reservoir development.

This project developed a series of spatial models to classify the island karst landforms and predict the island karst feature distribution. Spatial models with unsupervised classified images, and fuzzy-based spatial models were used in this study. Forecasting verification and spatial regressions were used to validate the models. The case study was conducted on San Salvador Island, the Bahamas, a recognized carbonate island with island karst features. Fieldwork data on banana holes on the island were used for model validation. The results showed that most models had accuracy higher than 90%, and were statistically proved that they could be used as predictors of island karst features. Further study may be conducted to solve the Modified Areal Unit Problem (MAUP) in the future.

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The Mariana Islands are a volcanic island chain in the western Pacific Ocean composed of Eocene volcanic cores with a carbonate mantle. Others have classified the cave and karst features into the cave types described in the CIKM, but no comprehensive GIS has been developed. For this project, a comprehensive GIS of the cave and karst features was developed. The cave and karst features were divided by cave type, physiographic province, and island. The karst features in the GIS were hyperlinked to a series of HTML pages, one for each island, and a set of HTML navigation pages mirroring the GIS layers were also created. LANDSAT images and Digital Raster Graphics were draped over the Digital Elevation Models for visualization. Attempts were made to remotely sense the vegetation and exposed soils and rocks from the LANDSAT images with the goal of producing a theoretical subsurface limestone/volcanic contact. Although the overall remote sensing aspect was unsuccessful, the GIS inventory was a success.

The purpose of this project was to distinguish between the karst and pseudokarst caves throughout Mississippi, create an inventory and survey of representative caves and karst features, identify the geology of the rocks hosting the caves, and produce a GIS-based digital karst map. The State of Mississippi is not known for its karst features, yet there are three distinct limestone units that contain dissolution caves: 1) Paleozoic (Mississippian) Tuscumbia Formation limestone; 2) Mesozoic carbonate units; and 3) Cenozoic limestone, Marianna Formation. There are a total of 44 caves known within the state based on past documentation, however the caves listed are not always differentiated between karst or pseudokarst features. This study located and mapped 20 caves, of which 18 were karst caves from eight counties and two were pseudokarst caves from two counties. Four of these caves were newly discovered karst caves, increasing the state total to 48; however two separate karst caves were connected, which makes the final state total 47 caves. Of the remaining 28 caves not surveyed, 11 were pseudokarst caves from eight counties and were not studied because the focus was on dissolutional karst caves. The remaining 17 missing karst caves either had been destroyed, access permission could not be obtained, or the caves could not be located. No active caving organizations exist in Mississippi to preserve cave location data or the caves themselves. Mining, deforestation, and other land use procedures have altered the landscape, resulting in concealment of some caves, and completely or partially destroying other caves.

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A finite-element model (HYDMATCH) uses spring hydrograph discharge data to generate a linear regression relation between fracture 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 mesh. A fracture-flow equation derived from the Navier-Stokes equation uses fracture conductivities from the regression equation and potential gradient in the last element of the mesh to determine discharge at the spring. Discharge hydrograph data from Nininger spring, located in Roanoke, Virginia, was used to test the performance of the model. Excess from a one-half inch rain was introduced into sinkhole nodes and the regression equation generated by matching discharges from the known hydrograph for the one-half inch rainfall. New rainfall excess data from a one-inch rainfall was input to the sinkhole nodes and routed through the finite-element mesh. The spring hydrograph for the one-inch rainfall was calculated using the regression equation which was determined previously. Comparison of the generated hydrograph for the one-inch rainfall to a known hydrograph for a one-inch rainfall shows similar shapes and discharge values. Areas in need of improvement in order to accurately model ground-water flow in karst aquifers are a reliable estimate of rainfall excess, a better estimation of baseflow and antecedent aquifer conditions, and the knowledge of the karst aquifer catchment boundaries. Models of this type may then be useful to predict flood discharges and contaminant travel times in karst aquifers. / Master of Engineering

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 quality of recharge to the aquifer. As the epikarst exhibits complex heterogeneity, characterization at the field scale can be challenging. The objective of this thesis was to develop a model of epikarst hydrodynamics using longterm field measurements. To meet this objective, continuous hydrologic data of precipitation, speleothem drips, and an underground stream in James Cave in Pulaski County, VA, were collected to delineate seasonal recharge patterns, estimate effective recharge and catchment areas, characterize the number and permeability of flow paths, and evaluate storativity in the epikarst. Results demonstrate that after significant seasonal recharge, which occurs in the late winter and early spring, the epikarst can temporarily store a significant portion of recharge in low permeability flow paths. Effective recharge was estimated to be approximately 30% of total precipitation (2008-2009). Hydrograph recession analysis aided in delineation of flowpaths in the epikarst, including quickflow, moderate flow, and baseflow components. Hydrograph shape analysis suggests flow restrictions at two of the drip sites that may reveal spatial differences in storage capacity and retention time. Results of this work are intended to aid karst aquifer management by providing a multitechnique approach that can be used to assess seasonal patterns of recharge, quantify flowpath and storage characteristics, and delineate recharge zones. / Master of Science