Spring Hydrograph Generation using LiDAR-Derived Cave Channel Geometry and Water Stage: A Case Study in the Karst Region of Northern Puerto Rico

Severe droughts, along with poorly managed groundwater use, have had devastating effects on groundwater availability in many regions around the globe. Since groundwater provides about 25 to 40 % of the world's drinking water, effective groundwater management must be enforced to avoid resource depletion and to ensure a sustainable water supply for future generations. A thorough understanding of the hydrologic processes governing groundwater spring discharge can provide critical data for sustainable groundwater management. This study evaluates the feasibility of correlating Light Detection and Ranging (LiDAR)-derived cave maps and stage measurements to generate spring hydrographs. LiDAR data were employed to define channel geometry in a 100-m cave located in the northern karst region of Puerto Rico. The LiDAR data, in combination with channel geometry parameters, such as wetted perimeter, cross-sectional area, and stage, helped calibrate a rating curve that allowed for the creation of a spring hydrograph, providing useful data on aquifer characteristics. The study shows that spring discharge response is observed shortly after heavy rain, indicating a direct influence from the unconfined aquifer or from surficial processes. Preliminary results show that due to the ongoing drought in the study area, recession conditions can be observed and can provide accurate quantification of the long-term minimum spring discharge, demonstrating that proper spring characterization can provide useful data for the implementation of successful strategies to maintain and restore groundwater resources.