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78-5 Assessing Groundwater Infiltration, Hydrological Response and Recharge Dynamics through Automated Cave Drip Monitoring: A study at Natural Bridge Caverns, Texas

Session: New Frontiers in Cave and Karst Science

Presenting Author:

Kashif Mahmud

Authors:

Remie, Rowann N.¹, Mahmud, Kashif², Gary, Marcus O.³, Price, Jonathan D.⁴, Katumwehe, Andrew B.⁵, Vauter, Brian⁶

(1) Kimbell School of Geosciences, Midwestern State University, Wichita Falls, TX, USA, (2) Kimbell School of Geosciences, Midwestern State University, Wichita Falls, TX, USA, (3) Jackson School of Geosciences, The University of Texas at Austin, San Marcos, TX, USA, (4) Kimbell School of Geosciences, Midwestern State University, Wichita Falls, TX, USA, (5) Boone Pickens School of Geology, Oklahoma State University, Stillwater, OK, USA, (6) Natural Bridge Caverns, San Antonio, TX, USA,

Abstract:

In Texas, groundwater from karst aquifers represents a significant percentage of the State’s water supply. Karst regions are critical hydrogeological systems, capable of storing and trasmitting substantial volumes of groundwater through extensive networks of solution-enlarged conduits, fractures, and voids within soluble rock formations. Caves offer natural access points for observing long-term vadose zone water storage and preferential flow, offering a better understanding of groundwater flow paths. Natural Bridge Caverns (NBC), which is situated within the recharge zone of the Edwards (Balcones Fault Zone) aquifer and contribution zone of the Trinity aquifer, was monitored with a high resolution, spatially dense cave discharge network during one hydrological year to characterize water infiltration within Cretaceous karst. Precipitation, soil water content (SWC) and evapotranspiration (ET) data was obtained for the location and used to evaluate infiltration-discharge relationship for 20 drip loggers. All drip sites remained active throughout the monitoring period, and generally exhibited low discharge rates during dry periods and high discharge rates in response to rainfall events. Discharge at the drip sites varied substantially, and analysis revealed a spatial relationship emerging from the dataset. Using Multidimensional Scaling (MDS) and agglomerative hierarchical clustering (AHC) we were able to classify similar drip types to obtain four unique drip regimes. A lithological assessment suggests that secondary porosity is influencing water movement rather than overburden thickness. Despite the relatively short time frame of this study, we find that the results shed valuable insights into the heterogeneity of hydrological flow within Cretaceous karst at Natural Bridge Caverns. It also emphasizes the importance of advancing our understanding and characterization of unsaturated zone hydrological processes to inform effective groundwater management policies.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-4526

Assessing Groundwater Infiltration, Hydrological Response and Recharge Dynamics through Automated Cave Drip Monitoring: A study at Natural Bridge Caverns, Texas

Description

Session Format: Oral

Presentation Date: 10/20/2025

Presentation Start Time: 09:20 AM

Presentation Room: HBGCC, 211

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