Revisiting a classification scheme for U.S.-Mexico alluvial basin-fill aquifers

Area of Science:

• Hydrogeology
• Environmental Science
• Geology

Background:

• Intermontane basins in Texas and Mexico are potential sites for municipal sludge and low-level radioactive waste disposal.
• Assessing contaminant fate and movement necessitates understanding groundwater dynamics within and between these basins.

Purpose of the Study:

• To evaluate and classify four associated basin aquifers: Red Light Draw, Northwest Eagle Flat, Southeast Eagle Flat, and El Cuervo.
• To determine groundwater movement and discharge patterns for risk assessment.

Main Methods:

• Hydrogeological classification of basin aquifers based on topography and drainage.
• Analysis of surface and groundwater discharge mechanisms.
• Assessment of interbasin groundwater flow and cross-formational flow.

Main Results:

• Red Light Draw Aquifer: Topographically open, through-flowing basin with the Rio Grande as the discharge outlet.
• Northwest Eagle Flat Aquifer: Topographically closed and drained, with discharge via interbasin groundwater flow, likely to underlying Permian rocks.
• Southeast Eagle Flat Aquifer: Topographically open and drained, discharging to Wildhorse Flat.
• El Cuervo Aquifer: Topographically closed basin, potentially partially drained to Indian Hot Springs or undrained, discharging to Laguna El Cuervo.

Conclusions:

• Groundwater flow systems in these basins exhibit significant variability, influencing contaminant transport.
• Classification of aquifers as open or closed is critical for predicting groundwater behavior and potential risks.
• Further investigation into interbasin flow is essential for comprehensive waste disposal site assessments.