Aquifer parameter estimation using an incremental area method

Abstract

Abstract:Theoretical well functions have been derived over the years to predict ground water level behaviour in aquifer systems under stress owing to groundwater extraction. The drawdown data collected during pump tests are typically analysed using graphical curve-matching procedures to estimate aquifer parameters based on these well functions. Difficulty in aquifer characteristic identification and parameter estimation may arise when the field data do not perfectly match the drawdown curves obtained from the well functions. The present study provides a new method for the interpretation of aquifer pump tests which supplements the existing curve-matching procedures in case ideal conditions do not exist; the proposed method provides a greater degree of flexibility in the data analysis for diagnostic tool purposes. The method, referred to as the Incremental Area Method (IAM) is based on integrating the logarithmic-based drawdown curves within a discrete time and matching the results with a corresponding time integral of the Theis (1935) Well Function which governs ideal confined aquifers. The application of the proposed method to synthetically generated data and field data showed that IAM represents a viable method which yields information on potential non-idealness of the aquifer and provides aquifer parameter estimates thus potentially overcoming drawdown data curve-matching difficulties.

Comparison of three methods of hydrogeological parameter estimation in leaky aquifers using transient flow pumping tests

“…TCFM relies on a set of type curves obtained from the well function, with the most important procedure being curve superposition to determine best fit. Although TCFM is one of the most popular methods for pumping test analysis and is even regarded as a standard for verifying the applicability and accuracy of other methods (Li, ), difficulty in aquifer characteristic identification and parameter estimation may arise when field data do not perfectly match the drawdown curves obtained from the well function (Avci et al ., ). TCFM also involves subjective judgment, which greatly influences the results.…”

“…The latter is preferable when estimating parameters as its associated calculation is more accurate than that of the former. It is widely believed that the transient flow theory first developed by Theis () forms the foundation of the majority of present‐day groundwater hydraulics theories, with many hydraulic tests and theoretical studies carried out on this basis (Rushton and Holt, ; Aziz and Wong, ; Samani et al ., ; Wen et al ., ; Avci et al ., , ). However, Theis did not consider leakage from adjacent aquifers or aquitards, making his theory inapplicable to leaky aquifer systems.…”

Assessing radial transmissivity variation in heterogeneous aquifers using analytical techniques

“…() and Avci et al . () have shown how information on the radial variability of the transmissivity field can be extracted from a single‐well pumping test data. Avci et al .…”

“…Avci et al . () have developed an integration technique for discrete portion of the drawdown data to assess changes in the hydraulic properties as the cone of depression expands during the pumping test. These methods, however, provide an averaging of the transmissivity field over the entire cone of depression assuming that all of the parts of the transmissivity field within the cone of depression equally influence the drawdown behaviour at the monitoring points.…”

“…() and Avci et al . () to show the improved characterization features of the proposed approach;To identify the best suited averaging methods for the heterogeneous transmissivity field within the cone of depression.…”