USE OF FIELD MEASUREMENT, FIELD-SCALE EXPERIMENTS, AND WATER-BUDGET ANALYSES TO DETERMINE DIFFUSE RECHARGE AND INFILTRATION ON KARST TERRAINS

Characterizing and quantifying diffuse recharge and infiltration can be significant sources of uncertainty when developing conceptual and numerical models of aquifers in karst and pseudo-karst terrains. Although characterizing and quantifying recharge for any hydraulic regime can be a challenge, achieving this in a karst or pseudo-karst terrain can be particularly difficult due to complexities due to flow and storage mechanisms inherent in epikarst and flow dynamics resulting from solutional preferential flow pathways. Insight on diffuse recharge and infiltration can be gained using approaches as diverse as field measurement (i.e., eddy covariance towers), field-scale experiments, and water-budget analyses. Improved results are possible when a variety of approaches is employed and compared. This presentation reviews case studies that employ a range of techniques to measure diffuse recharge and infiltration in karst terrains in south-central Texas that experience semi-arid to sub-humid climates.