DETERMINING VULNERABILITY IN KARST TERRAINS: QUANTIFYING IMPORTANT TRANSPORT PATHWAYS IN KARST AQUIFERS OF THE OZARK PLATEAUS

The highly soluble nature of carbonate rocks in the Ozark Plateaus has given rise to development of a distinctive karst terrain with a pervasive occurrence of caves, springs, sinkholes and other karst features. The Ozark Plateaus aquifer system contains two major karst aquifers, the Springfield Plateau aquifer and the Ozark aquifer, which serve as sources of water for many uses including domestic and municipal water supply. Because soils are generally thin, rocky, and poorly suited for row-crop farming in the area, land is predominantly used for poultry, cattle (beef and dairy), and swine production. Anthropogenic land-use changes resulting primarily from the conversion of forest to pasture for beef cattle and land application of wastes from concentrated animal feeding operations, together with the potential for surface-derived contaminants to enter the karst aquifers with little to no attenuation, have severe implications for widespread water-quality degradation of the Springfield Plateau and Ozark aquifers. In the last decade, numerous studies have resulted in an improved understanding of the hydrology of the karst aquifers, their vulnerability to nutrients from animal production, identification of the relation of groundwater nitrate concentrations with percent agricultural land use, and the effect of differing degrees of karst development on nitrate concentrations for similar land-use settings. A recent collaborative project with the U.S. Geological Survey, the National Park Service, and the Arkansas Department of Health resulted in the digitization of sinkholes, springs, and caves from all available historic and recent topographic maps. Currently, efforts are in place to use all available water-quality data and the digitized karst maps in concert with recent machine-learning techniques to develop a realistic tool for use by land-use managers and planners to protect groundwater and stream-water quality. The main objective of this project is to provide an easy-to-use tool for State and Federal agencies, municipal water suppliers, and other entities in protecting water resources not only in Arkansas, but also provide a uniform methodology to identify vulnerability in other karst aquifers throughout the United States.