Wu Jianfeng, Zheng Chunmiao, Chien Calvin C
Department of Geological Sciences, University of Alabama, Tuscaloosa, AL, United States.
J Contam Hydrol. 2005 Mar;77(1-2):41-65. doi: 10.1016/j.jconhyd.2004.11.006. Epub 2005 Jan 20.
A new simulation-optimization methodology is developed for cost-effective sampling network design associated with long-term monitoring of large-scale contaminant plumes. The new methodology is similar in concept to the one presented by Reed et al. (Reed, P.M., Minsker, B.S., Valocchi, A.J., 2000a. Cost-effective long-term groundwater monitoring design using a genetic algorithm and global mass interpolation. Water Resour. Res. 36 (12), 3731-3741) in that an optimization model based on a genetic algorithm is coupled with a flow and transport simulator and a global mass estimator to search for optimal sampling strategies. However, this study introduces the first and second moments of a three-dimensional contaminant plume as new constraints in the optimization formulation, and demonstrates the proposed methodology through a real-world application. The new moment constraints significantly increase the accuracy of the plume interpolated from the sampled data relative to the plume simulated by the transport model. The plume interpolation approaches employed in this study are ordinary kriging (OK) and inverse distance weighting (IDW). The proposed methodology is applied to the monitoring of plume evolution during a pump-and-treat operation at a large field site. It is shown that potential cost savings up to 65.6% may be achieved without any significant loss of accuracy in mass and moment estimations. The IDW-based interpolation method is computationally more efficient than the OK-based method and results in more potential cost savings. However, the OK-based method leads to more accurate mass and moment estimations. A comparison of the sampling designs obtained with and without the moment constraints points to their importance in ensuring a robust long-term monitoring design that is both cost-effective and accurate in mass and moment estimations. Additional analysis demonstrates the sensitivity of the optimal sampling design to the various coefficients included in the objective function of the optimization model.
针对与大规模污染物羽流长期监测相关的经济高效采样网络设计，开发了一种新的模拟优化方法。新方法在概念上与Reed等人（Reed, P.M., Minsker, B.S., Valocchi, A.J., 2000a. 使用遗传算法和全局质量插值的经济高效长期地下水监测设计。水资源研究。36(12)，3731 - 3741）提出的方法类似，即基于遗传算法的优化模型与水流和输运模拟器以及全局质量估计器相结合，以寻找最优采样策略。然而，本研究引入了三维污染物羽流的一阶矩和二阶矩作为优化公式中的新约束，并通过实际应用展示了所提出的方法。相对于输运模型模拟的羽流，新的矩约束显著提高了从采样数据插值得到的羽流的准确性。本研究采用的羽流插值方法是普通克里格法（OK）和反距离加权法（IDW）。所提出的方法应用于一个大型现场场地抽提处理作业期间羽流演变的监测。结果表明，在质量和矩估计没有任何显著精度损失的情况下，可实现高达65.6%的潜在成本节约。基于IDW的插值方法在计算上比基于OK的方法更高效，并且能带来更多潜在成本节约。然而，基于OK的方法能得到更准确的质量和矩估计。有无矩约束情况下获得的采样设计的比较表明，它们对于确保一个既经济高效又在质量和矩估计方面准确的稳健长期监测设计很重要。进一步分析表明了最优采样设计对优化模型目标函数中包含的各种系数的敏感性。
