Chitsazan Nima, Pham Hai V, Tsai Frank T-C
Department of Civil and Environmental Engineering, Louisiana State University, 3418G Patrick F. Taylor Hall, Baton Rouge, LA 70803.
Ground Water. 2015 Nov-Dec;53(6):908-19. doi: 10.1111/gwat.12304. Epub 2014 Dec 15.
The groundwater community has widely recognized geological structure uncertainty as a major source of model structure uncertainty. Previous studies in aquifer remediation design, however, rarely discuss the impact of geological structure uncertainty. This study combines chance-constrained (CC) programming with Bayesian model averaging (BMA) as a BMA-CC framework to assess the impact of geological structure uncertainty in remediation design. To pursue this goal, the BMA-CC method is compared with traditional CC programming that only considers model parameter uncertainty. The BMA-CC method is employed to design a hydraulic barrier to protect public supply wells of the Government St. pump station from salt water intrusion in the "1500-foot" sand and the "1700-foot" sand of the Baton Rouge area, southeastern Louisiana. To address geological structure uncertainty, three groundwater models based on three different hydrostratigraphic architectures are developed. The results show that using traditional CC programming overestimates design reliability. The results also show that at least five additional connector wells are needed to achieve more than 90% design reliability level. The total amount of injected water from the connector wells is higher than the total pumpage of the protected public supply wells. While reducing the injection rate can be achieved by reducing the reliability level, the study finds that the hydraulic barrier design to protect the Government St. pump station may not be economically attractive.
地下水领域已广泛认识到地质结构不确定性是模型结构不确定性的主要来源。然而，以往关于含水层修复设计的研究很少讨论地质结构不确定性的影响。本研究将机会约束（CC）规划与贝叶斯模型平均（BMA）相结合，形成一个BMA-CC框架，以评估地质结构不确定性在修复设计中的影响。为实现这一目标，将BMA-CC方法与仅考虑模型参数不确定性的传统CC规划进行了比较。采用BMA-CC方法设计了一道水力屏障，以保护路易斯安那州东南部巴吞鲁日地区政府街泵站的公共供水井免受“1500英尺”砂层和“1700英尺”砂层中的盐水入侵。为解决地质结构不确定性问题，基于三种不同的水文地层结构开发了三个地下水模型。结果表明，使用传统的CC规划会高估设计可靠性。结果还表明，至少需要额外增加五口连接井才能达到90%以上的设计可靠性水平。连接井的总注水量高于受保护公共供水井的总抽水量。虽然通过降低可靠性水平可以实现降低注水率，但研究发现，保护政府街泵站的水力屏障设计在经济上可能并不具有吸引力。
