Codification of a fuzzy simulation-optimization model for optimal estimation of confined aquifer parameters based on a fuzzy transformation method

For proper groundwater resource management as a vital resource, accurate aquifer parameter determination is required. Existing groundwater management practices, for the sake of simplicity, overlook inherent uncertainties in measurements of pumping test parameters. In the current study a fuzzy simulation-optimization model based on consideration of uncertainties in parameter determination is used. To this regard, the novel fuzzy simulation-optimization model is able to predict the confined aquifer parameter precisely, based on minimizing the deviation between observed and calculated drawdown. The proposed approach is tested on a real pumping test data of a confined aquifer and then the results are compared with graphical solution of Theis method. Comparing several statistical indices based on the results of the proposed method and graphical solution of Theis method, performance of these models are evaluated. As an example, Mean Absolute Relative Error (MARE) of the proposed model and graphical Theis solution is 0.69% and 1.13% respectively which shows the appropriate accurate of the proposed model over the traditional method (graphical Theis solution). Thus, the proposed fuzzy simulation-optimization model may replace the graphical Theis solution. In the second part of the study, by considering pumping rate as an uncertain parameter, a fuzzy optimization model based on fuzzy transformation method is developed. Then, the effect of uncertainty in prediction of aquifer parameters is assessed and ranges of aquifer parameters in various α cuts, are determined. Based on the developed fuzzy results, T is found more sensitive to uncertainty in the pumping rate measurements, as compared to S.