Comparison of Two Computational Methods for Estimating Transmissivity Based on the Picking Equation

Area of Science:

• Hydrogeology
• Geophysical Well Logging

Background:

• Accurate estimation of aquifer transmissivity is crucial for managing groundwater resources, especially in low-yielding domestic wells.
• Traditional methods for transmissivity estimation can be time-consuming and require specialized software.

Purpose of the Study:

• To compare the efficacy of two computational methods, PICKINGmodel and PPC-Recovery, for estimating transmissivity using water-level recovery data.
• To evaluate the PPC-Recovery method as a potentially faster and less labor-intensive alternative to PICKINGmodel for low-yielding domestic wells.

Main Methods:

• Pumping tests were conducted in 50 domestic bedrock wells in south-central New York State by the United States Geological Survey (USGS).
• Water-level recovery data from these tests were analyzed using the PICKINGmodel and PPC-Recovery, both based on the Picking equation.
• The PPC-Recovery method was also applied to truncated recovery data to assess its performance under modified conditions.

Main Results:

• Estimated transmissivities ranged from 0.86 to 2900 ft²/d, with a median of 41 ft²/d.
• Statistical comparison showed no significant difference between transmissivity values estimated by PICKINGmodel and PPC-Recovery (95% probability).
• PPC-Recovery applied to truncated data also yielded statistically similar median transmissivity values compared to PICKINGmodel.

Conclusions:

• The PPC-Recovery method provides transmissivity estimates comparable to PICKINGmodel for low-yielding domestic wells.
• Using PPC-Recovery, particularly with truncated data, offers a viable and more efficient alternative for transmissivity estimation, saving time and effort.