Andersen Peter F, Lu Silong
GeoTrans Inc., 1080 Holcomb Bridge Rd., Bldg. 100, Ste. 190, Roswell, GA 30076, USA.
Ground Water. 2003 Mar-Apr;41(2):212-8. doi: 10.1111/j.1745-6584.2003.tb02584.x.
Model post audits test the predictive capabilities of ground water models and shed light on their practical limitations. In the work presented here, ground water model predictions were used to design an extraction/treatment/injection system at a military ammunition facility and then were re-evaluated using site-specific water-level data collected approximately one year after system startup. The water-level data indicated that performance specifications for the design, i.e., containment, had been achieved over the required area, but that predicted water-level changes were greater than observed, particularly in the deeper zones of the aquifer. Probable model error was investigated by determining the changes that were required to obtain an improved match to observed water-level changes. This analysis suggests that the originally estimated hydraulic properties were in error by a factor of two to five. These errors may have resulted from attributing less importance to data from deeper zones of the aquifer and from applying pumping test results to a volume of material that was larger than the volume affected by the pumping test. To determine the importance of these errors to the predictions of interest, the models were used to simulate the capture zones resulting from the originally estimated and updated parameter values. The study suggests that, despite the model error, the ground water model contributed positively to the design of the remediation system.
模型后审计测试地下水模型的预测能力，并揭示其实际局限性。在本文介绍的工作中，地下水模型预测被用于设计一个军事弹药设施的抽取/处理/注入系统，然后使用系统启动大约一年后收集的特定场地水位数据进行重新评估。水位数据表明，设计的性能规格，即围堵，在所需区域已实现，但预测的水位变化大于观测值，特别是在含水层的较深区域。通过确定为获得与观测水位变化更好的匹配所需的变化来研究可能的模型误差。该分析表明，最初估计的水力特性误差为二到五倍。这些误差可能是由于对含水层较深区域的数据重视不够，以及将抽水试验结果应用于大于抽水试验影响体积的材料体积所致。为了确定这些误差对感兴趣的预测的重要性，使用模型模拟了由最初估计和更新的参数值产生的捕获区。研究表明，尽管存在模型误差，但地下水模型对修复系统的设计仍有积极贡献。
