Pumping test in a confined aquifer under tidal influence

Area of Science:

• Hydrogeology
• Coastal Groundwater Hydrology
• Aquifer Testing

Background:

• Pumping tests are crucial for understanding aquifer properties.
• Tidal influences in coastal environments introduce significant head fluctuations.
• These fluctuations complicate the interpretation of drawdown data, leading to potential inaccuracies in aquifer parameter estimation.

Purpose of the Study:

• To develop and validate a method for correcting tidal effects in pumping test data from confined aquifers.
• To enable reliable aquifer characterization in coastal settings despite tidal interferences.

Main Methods:

• Application of the superposition principle to derive a closed-form solution for tide-affected confined aquifers with sinusoidal tides.
• Subtraction of net tidal effects from observed drawdown data.
• Validation through numerical simulations.

Main Results:

• A method was successfully developed to isolate aquifer response from tidal influences.
• Corrected drawdown data become suitable for standard pumping test analysis techniques.
• Numerical simulations confirm the method's reliability within a specific distance ratio (monitoring well to tidal boundary).

Conclusions:

• The proposed method effectively removes tidal effects, simplifying the analysis of pumping tests in coastal confined aquifers.
• This approach enhances the accuracy of aquifer parameter determination in tidally influenced environments.
• The method is reliable when monitoring wells are located within 10% of the distance to the tidal boundary.