119 Recent Investigations of the Hydrogeology Edwards (Balcones Fault Zone) Aquifer, the Trinity (Hill Country) Aquifer, and Their Interactions, South-Central Texas

Recent research into the hydrogeological characteristics of the Edwards (Balcones Fault Zone) and/or Trinity (Hill Country) aquifers, south-central Texas, including their inter-aquifer connections, vulnerability, and prospects for long-term sustainability given changes in population, land use, and climate of the region.

Monday, 20 October 2025
1:30 PM - 5:30 PM
HBGCC, 209

Impacts of the current drought on the Edwards and Trinity aquifer systems: Are there implications for the future?

Paper number: 119-13
Program: Technical Sessions
Time: 4:45 PM – 5:00 PM

Authors

Abstract

The Edwards and Trinity aquifers are critical sources of water for south-central Texas. Both are karstic-carbonate systems, but they differ in many important aspects: the Edwards Aquifer is highly productive and recharges relatively rapidly, while the Trinity Aquifer system is more fragmented, less productive overall, and recharges slowly in some areas and quickly in others. Since early 2022, the region has experienced significant drought. The current drought is the second longest and most intense on record from a groundwater perspective and likely the new drought of record for some river basins. The drought has been a product of extremely low precipitation, lack of precipitation in critical areas, and high maximum and minimum temperatures in the region. Increasing water demands on the Trinity Aquifer likely exacerbated the drought's effects on that system.

Despite recent major flooding in the region, the drought has persisted from a groundwater standpoint. Several reservoirs that were severely affected by the drought have recovered, but groundwater levels have been slow to respond. However, analyses of historical data suggest the aquifers are responding as they have in the past given the magnitude and location of rainfall.

The current drought marks the second major regional drought in the past 20 years, following a six-decade gap since the 1950’s drought of record. Projections of recharge and Edwards Aquifer conditions using regionally specific downscaled global climate models indicate droughts like the current one may occur more frequently in the next 50 years. These findings underscore the importance of accounting for this projected change in drought frequency in long-term water resource planning for both aquifers.

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

doi: 10.1130/abs/2025AM-414268

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