JC METHOD FOR UNCERTAINTY ANALYSIS IN EVALUATION OFGROUNDWATERALLOWABLE WITHDRAWAL

摘要

Calculation of groundwater allowable withdrawal is the key task of evaluating groundwater resources. However, thernprecise amount of groundwater allowable withdrawal is under uncertainties associated with the real values of the parameters andrnsimplification of mathematical model. The traditional deterministic method of water balance evaluation has a number of limitations,rnand the risk associated with the results is overwhelming. In this study, JC method which is an improvement method of first-orderrnsecond-moment is used in determining the groundwater allowable withdrawal for the well field in Jining City, Shandong Province,rnChina. First, this method transforms the non-normal distribution of random variables to the normal distribution, and then employs arnFirst-Order Taylor series expansion to combine model sensitivity with uncertainty in the design check point. Based on the sensitivityrnanalysis carried out, transmissivity, coefficient of leakage, and the gradient and head difference between deep confined aquifer andrnshallow phreatic aquifer are chosen as the random variables in the research area and their distributions are considered as lognormalrnand normal distribution, respectively. Using the JC method, the reliability of groundwater allowable withdrawal and differentrngroundwater pumpage are analyzed with different probability density function. Results show that JC method in evaluation ofrnallowable groundwater withdrawal (GWAW) has higher reliability due to uncertainties considerations. An attempt is made to explainrnthe results and influence of variable parameters on the JC method.