A New Inverse Solution Assessment for the Recovery Test Using Radial Basis Function Collocation Method

Abstract

Recovery pumping tests are still one of the most commonly preferred preliminary design steps in the assessment of aquifer hydraulics. The use of the existing methods would be insufficient under non-ideal aquifer conditions (i.e. heterogeneity, measurement errors, and boundary effect, etc.) which violate the Theis model assumptions developed for recovery test analysis. In this study, a new parameter estimation methodology based on the Radial Basis Collocation Method (RBFCM) was formulated to access the hydraulic parameters in a reliable, robust and accurate manner using recovery pump test. The suggested approach was established on the idea that the dimensionless time value at the pump-cessation which serves as a matching value is obtained by means of RFBCM. The proposed approach is straightforward to implement; which requires no data refinement, additional parameter, and visual match. The performance of the proposed method was tested with several aquifer conditions including homogeneous synthetic data, heterogeneous aquifer simulation and real field applications. The results confirm that the proposed method has a parameter estimation capacity as high as the available techniques in the literature and provides the practitioners to understand a more accurate portrayal of the effects of heterogeneity on the hydraulic parameters during the test process. In addition, the suggested methodology for the interpretation of aquifer recovery test can be evaluated to be employed as a diagnostic tool to identify non-ideal conditions. The potential use of RBFCM in this study was also presented as the supplement of aquifer test interpretation assessment.