Discharge-Targeted Hydraulic Tomography to Quantify and Locate Aquifer Discharge

Area of Science:

• Hydrogeology
• Environmental Science
• Geophysics

Background:

• Quantifying groundwater discharge is challenging due to complex hydrogeological conditions.
• Conventional methods like pumping tests can be unreliable with heterogeneity and structural boundaries.
• Advanced hydraulic tomography is often limited by scale and cost.

Purpose of the Study:

• To develop and test a simplified tomographic approach for quantifying groundwater discharge and its uncertainty.
• To infer spatially variable hydraulic conductivity fields from pumping test data.
• To improve the reliability and spatial resolution of discharge estimations.

Main Methods:

• A simplified tomographic approach using a limited number of spatially distributed pumping and observation wells.
• Application of an iterative ensemble smoother to infer hydraulic conductivity fields from drawdown data.
• Calculation of total and specific discharge using posterior hydraulic conductivity ensembles and observed hydraulic heads.

Main Results:

• The proposed method reliably quantifies total groundwater discharge and associated uncertainty.
• The tomographic analysis provides spatial patterns of specific discharge at well-spacing resolution.
• The approach demonstrates higher reliability than conventional methods for estimating transmissivity.

Conclusions:

• Spatially distributed pumping tests offer a reliable method for quantifying groundwater discharge.
• The simplified tomographic approach enhances the assessment and remediation of contaminant plumes.
• This method provides a more robust alternative to conventional hydrogeological testing.