Sources of groundwater pumpage in a layered aquifer system in the Upper Gulf Coastal Plain, USA

• Published in: Hydrogeology journal 2012-06, Vol.20 (4), p.783-796
• Main Authors: Huang, Yun, Scanlon, Bridget R., Nicot, Jean-Philippe, Reedy, Robert C., Dutton, Alan R., Kelley, Van A., Deeds, Neil E.
• Format: Article
• Language: English
• Subjects: Aquatic Pollution; Aquifer systems; Aquifers; Base flow; Coastal plains; Confined aquifers; Discharge; Earth and Environmental Science; Earth Sciences; Evapotranspiration; Flow system; Freshwater; Geology; Geophysics/Geodesy; Groundwater; Groundwater data; Groundwater flow; Groundwater storage; Gulfs; Hydrogeology; Hydrologic data; Hydrology/Water Resources; Pumpage; Pumps; Regional; Simulation; Stream discharge; Stream flow; Streams; Sustainability; Unconfined aquifers; Vertical flow; Waste Water Technology; Water Management; Water Pollution Control; Water Quality/Water Pollution; Water resources
• ISSN: 1431-2174; 1435-0157
• DOI: 10.1007/s10040-012-0846-2

Understanding groundwater-pumpage sources is essential for assessing impacts on water resources and sustainability. The objective of this study was to quantify pumping impacts and sources in dipping, unconfined/confined aquifers in the Gulf Coast (USA) using the Texas Carrizo-Wilcox aquifer. Potentiometric-surface and streamflow data and groundwater modeling were used to evaluate sources and impacts of pumpage. Estimated groundwater storage is much greater in the confined aquifer (2,200 km 3 ) than in the unconfined aquifer (170 km 3 ); however, feasibility of abstraction depends on pumpage impacts on the flow system. Simulated pre-development recharge (0.96 km 3 /yr) discharged through evapotranspiration (ET, ∼37%), baseflow to streams (∼57%), and to the confined aquifer (∼6%). Transient simulations (1980–1999) show that pumpage changed three out of ten streams from gaining to losing in the semiarid south and reversed regional vertical flow gradients in ∼40% of the entire aquifer area. Simulations of predictive pumpage to 2050 indicate continued storage depletion (41% from storage, 32% from local discharge, and 25% from regional discharge capture). It takes ∼100 yrs to recover 40% of storage after pumpage ceases in the south. This study underscores the importance of considering capture mechanism and long-term system response in developing water-management strategies.