Geo-sphere Research Institute, Department of Civil and Environmental Engineering, Saitama University, 255, Shimo Okubo, Sakura-Ku, Saitama City, Saitama, 338-8570, Japan,
Environ Monit Assess. 2014 Feb;186(2):1063-81. doi: 10.1007/s10661-013-3439-1. Epub 2013 Oct 4.
Groundwater flow at Kharga Oasis, located in the western desert of Egypt, was previously analyzed using numerical models; however, the lack of basic data often limits the implementation of these models, as well as introducing a problem for model calibration and validation. The Grey Model (GM) was used to overcome these difficulties of data limitation and uncertainty of hydrogeological conditions. However, no clear theories exist for selecting the number of input model trends and the most suitable values of input parameters. Therefore, in the current study, a modification of the GM is newly proposed and called the Modified Grey Model (MGM) in an attempt to determine a process for selecting the best input models' trends with the appropriate values of input parameters to achieve acceptable fitting to observations. The sensitivity analysis results showed that the MGM produced more stable results than the GM using a wide range of values for input parameters. Moreover, the MGM reduced the calculation time required for fitting the measured piezometric level trends by 99.8%. Three development scenarios of groundwater withdrawal were proposed that involved either expanding the present extraction rate or redistributing the groundwater withdrawal over the recent working production wells (RWPWs). The results concluded that the groundwater table in the northern part of the oasis could be temporally recovered to an economical piezometric level; however, the table in the southern part is severely decreased. Therefore, new production wells are recommended to be constructed in the southern part far enough from the RWPWs.
先前曾使用数值模型对位于埃及西部沙漠的 Kharga 绿洲的地下水流动进行了分析；然而，基本数据的缺乏通常会限制这些模型的实施，并为模型校准和验证带来问题。灰色模型（GM）被用于克服数据限制和水文地质条件不确定性的这些困难。然而，对于选择输入模型趋势的数量和输入参数的最佳值，目前还没有明确的理论。因此，在当前的研究中，提出了对 GM 的一种改进，称为改进的灰色模型（MGM），试图确定选择最佳输入模型趋势的过程，并确定输入参数的适当值，以实现对观测值的可接受拟合。敏感性分析结果表明，MGM 比 GM 产生了更稳定的结果，因为它使用了广泛的输入参数值。此外，MGM 将拟合测量的测压水位趋势所需的计算时间减少了 99.8%。提出了三种地下水开采的发展方案，包括扩大目前的开采率或重新分配最近的工作生产井（RWPWs）的地下水开采。结果表明，绿洲北部的地下水位可以暂时恢复到经济测压水位；然而，南部的地下水位却严重下降。因此，建议在远离 RWPWs 的南部地区建造新的生产井。
