Southwest of Bowling Green, Kentucky, is the Western Pennyroyal, is a karstified area which has been neglected in the study of its ground water. About 100 square miles near Adairville were chosen for analysis to help rectify this lack of knowledge. The area is dominated by Sinking Creek, a surface-subsurface drainage system. The main purpose of the study was to map the underground flow in the Sinking Creek area. The drainage system seemed to be typical for the Western Pennyroyal and exhibited many similarities to flow paths known in the Central Kentucky Karst. The investigation proved to be of basic value to future studies dealing with water well location, pollution of subsurface streams and karst-related flooding problems. The geographic scope of the study area extends from the rise of Sinking Creek to the origin of its headwaters in the residual outlying knobs of the Dripping Springs Escarpment to the north. Most of the area is a sinkhole plain developed mainly on the Ste. Genevieve and St. Louis limestones of Mississippian age. Map and field reconnaissance of the study area revealed the presence of 12 sinking streams, 6 resurgences and 5 caves, all occurring at or below 600 feet in elevation. On the basis of the physical features mentioned, two hypotheses were devised to explain their development and their relationship to the hydrology of the area. The first hypothesis was that the sinking stream and resurgences in the study area are connected in a single drainage system. This hypothesis was testable by physically determining subsurface connections in the field. The second hypothesis was that the sinking streams are controlled by the stratigraphy of the lithologic units. Diversion of surface streams occurs at or near the 600 foot elevation level, upon flowing from the Ste. Genevieve to the St. Louis limestone. This hypothesis was field tested by standard geologic methods. The determination of surface-subsurface stream connections was carried out by standard water tracing techniques using Rhodamine W.T. dye (20 percent solution) and fluorescein dye. The dye was injected into the streams, and samples were collected and then analyzed in the laboratory with a Turner fluorometer. Positive dye connections were obtained in all 5 traces. In addition to dye tracing, a large amount of field reconnaissance and subsurface mapping was necessary to determine the nature of the geologic controls on the surface-subsurface drainage system. Numerous rock outcrops and 5 caves were explored; one cave was mapped for over 4,000 feet. The lithologic studies proved to be inconclusive for the entire study area, but enough evidence was collected to support lithologic stream control in one cave stream segment. The culmination of the research design was to present the results of dye tracing and field work with a written description, graphs, and especially a map showing the connections established by the research.

The laboratory-derived calcite dissolution rate law of Plummer et al. (1978) is the most widely used and mechanistically detailed expression currently available for predicting dissolution rates as a function of water chemistry. Such rate expressions are of great use in understanding timescales associated with limestone karst development. Little work has gone into the field testing of the rate law under natural conditions. This work compared measured dissolution rates measured by a crystal weight loss experiment in Buffalo Creek within Fort’s Funnel Cave, which lies within a pristine, forested catchment of Mammoth Cave National Park. Continuous water chemistry sampling over the same period allowed a time-integrated prediction of the dissolution based on the Plummer et al (1978) expression. Results indicate that the rate law overpredicted dissolution by a factor of about ten. This concurs with earlier laboratory work suggesting that the law tends to overpredict rates in solutions close to equilibrium with respect to calcite, as were the waters in this study. Estimating dissolution rates with the expression under varying hydrologic conditions also allowed a prediction of storm scales change in cave forming processes. Neglecting effects of sediment masking on the bed, it was found that 78% of the work done in the dissolution of the cave passage during the study period occurred at or around baseflow conditions, with only a small amount during the effective but infrequent high flow conditions.

Eighty-nine caves and sinkholes were investigated in the Edwards Aquifer recharge zone in Bexar County, Texas. The study examined their hydrogeologic and topographic origins and distribution, relationships to major fracture traces, quantity of recharge into the aquifer and degree of sensitivity towards degradation of the aquifer’s water quality. Groundwater traces were attempted to determine aquifer flow routes, time of groundwater travel, groundwater volume within conduits, and the aquifer’s capacity for dilution and dispersion of recharged contaminants. Trends in water quality were examined to quantify the volume and variety of contaminants recharged into the aquifer and to determine the effects of urbanization upon the Edwards Aquifer. The Edwards recharge zone was hydrogeologically assessed to rate the sensitivity of its areas. Socio-political impacts on recharge zone development were also examined. Based on the results of the above outlined research method, the conclusions of this investigation are that caves and sinkholes contribute substantial recharge into the Edwards Aquifer, rapidly transmit that recharge to the aquifer and are sensitive sites for potential contamination. The entire recharge zone was determined to be very sensitive to contamination. No significant differences were found between areas within the recharge zone to scale their degree of sensitivity. Major conduit flow networks were found to exist within the aquifer and their groundwater flow paths could be traced. Urban development of the Edwards recharge zone was shown to decrease the volume of recharge and degrade the aquifer’s water quality. No significant detrimental effects on the aquifer were observed. The volume of diminished recharge and the concentration of recharged contaminants that were necessary to produce significant adverse effects on the aquifer were not determined due to lack of precipitation during the study period and inconclusive groundwater tracings. It was recommended that further development of the recharge zone be suspended until the effects of urbanization are quantified.

Hydrogeologic investigations were conducted on the drainage systems of an area of the Pennyroyal sinkhole plain of south central Kentucky. The degree of karstification of five area streams was studied to develop an understanding of the evolution of drainage as the landscape changes from a sandstone caprock plateau to a limestone sinkhole plain. The Chester Upland, capped by the Big Clifty Sandstone, possesses predominantly surface drainage and the Pennyroyal Plain, formed on Mississippian limestones, possesses considerable subsurface drainage. As the Chester Upland Escarpment retreats and surface streams are onto the limestones, the streams evolve to become subsurface streams. The five streams observed in the study (all flowing on limestones) demonstrated less karst development close to the Chester Escarpment and more karst development with increasing distance from the escarpment. Sediments derived from the escarpment and plateau blanket the stream beds thus perching the streams and preventing chemically aggressive water from forming karst solution features in the limestones. The streams farther away from the escarpment are removed from the sediment source and are therefore able to downcut into the limestone and invade the subsurface to become cave streams. Lithologic investigation of limestones exposed in stream beds revealed that minor resistant units can act to diminish downcutting and maintain short sections of surface flow. The stream investigated was not flowing on a perching layer, but instead was held on the surface by a stratigraphic control (spillover layer) that prevented subterranean stream invasion. Dye traces conducted on groundwater flow in the sinkhole plain revealed that the area drainage pattern is changing as surface streams invade the subsurface and that integration between drainage basins is taking place. Stream piracy and stream diversion are occurring in the subsurface causing alteration of the existing topographic drainage divides that developed before the surface streams invaded the subsurface. A general model is presented which shows the evolution of surface drainage to subsurface drainage, as the Chester Escarpment continues its northwestward retreat.