THE EFFECTS OF LAND-USE CHANGE ON WATER QUALITY AND SPELEOGENESIS IN OZARK CAVE SYSTEMS - A PAIRED CAVE STUDY OF CIVIL WAR AND COPPERHEAD CAVE, NORTHWESTERN ARKANSAS

Much of the Ozark Region is characterized by shallow mantled karst developed on lower Mississippian chert-bearing limestones. Caves typically are well connected hydraulically to the land surface and show a rapid response to rain events. In a natural setting, this vulnerability means that the amount of water in the cave increases rapidly with rain events; however, in a developed setting this connection means that the water quality as well as quantity entering the cave system changes rapidly after a rain event. Consequently, these caves are vulnerable to the land use in the recharge area. Changing water quality can have a dramatic effect on the delicate cave ecosystem. This study characterizes the effects of land-use change on water quality and speleogenesis using a paired cave study. One of the caves, Civil War Cave, lies in a highly impacted area just outside Bentonville, Arkansas. Much of the land surrounding this cave recently has been developed from forested and light agricultural to residential and light industrial use. Copperhead Cave lies within a forested watershed of the Buffalo National River which is considered to be a non-impacted recharge area. Copperhead Cave represents a cave with near pristine water quality. Data collected bear out the intimate connection of the cave systems with surface waters and the impact of local land use. Water samples from Civil War cave exhibit elevated nitrate and chloride levels, as well as high turbidity and sedimentation rates, all indicative of human activities in the recharge area.