LIDAR-DRIVEN INSIGHTS INTO GROUNDWATER RECHARGE DYNAMICS IN KARST SYSTEM

The Natural Bridge Caverns (NBC) in Comal County, Texas, are made of Cretaceous limestone that has been dissolved and chipped away over time by water infiltration. NBC is located near San Antonio, along the recharge zone of the Edwards BFZ (Balcones Fault Zone) aquifer. This aquifer is a key groundwater resource for various industries and tourism that provides important ecosystem services. Moreover, groundwater recharge is crucial for water management, water cycle, climate research, and contaminant transport. This study uses automated cave drip monitoring and remote sensing LiDAR data from NBC to quantify cave-scale groundwater recharge. By examining drip rates, stalactite morphology, and climate data, we will estimate total water infiltration. 3D images of the cavern ceiling were captured using a LiDAR to cover the entire cave section called Discovery Passage. Moreover, we installed 30 automated drip loggers in the same cave section to continuously monitor water drips. First, we will analyze the spatial and geometric properties of the cavern's ceiling features from the LiDAR point cloud to classify different types of water infiltration pathways. We will then consider one year of drip time series to calculate the total drip counts for each logger and thus obtain the total cave-integrated drip water volume. This innovative approach not only enhances the understanding of recharge dynamics in karst systems but can also be applied to other cave sites to identify concentrated recharge areas and improve total recharge volume estimations.