熵权耦合随机理论在含水层非均质综合指数研究中的应用

摘要

The tradition methods mainly focus on using single aquifer property to characterize qualitatively or semi-quantitatively heterogeneity of aquifer, they did not reflect the synthetic heterogeneity of aquifer properties. In this paper, the heterogeneity synthetic index ( HIS) was introduced to characterize synthetic heterogeneity of aquifer. The calculation process included three steps: first, used the Markov chain to establish sedimentary micro-facies distribution model; second, through the ' facies-controlled modeling' technique, the improved sequential simulation method was employed to characterize distribution model of hydrogeology parameter; Finally, application of the entropy weight method was used to calculate weight coefficient of the above aquifer property, by superposition of these models according to its weight coefficient, the HIS of aquifer was calculated.This approach was applied to Luancheng aquifer deposit in the southeast Hutuo River alluvial-pluvial fan in the North China Plain (NCP). The results indicated that the heterogeneity was weak in the radial direction of alluvial-pluvial fan due to the micro-facies changed mildly and the continuity of hydrogeology parameter was better, the HIS was 0. 74 - 0. 95; while in the superstition zone of alluvial-pluvial fan, the heterogeneity of aquifer was stronger, HIS was 0. 38 - 0. 65. The sedimentary environment had significant effect on heterogeneity of aquifer. Therefore based on considering many aquifer properties, HIS could characterize quantitatively the synthetic heterogeneity of aquifer, and calculate the influence of each aquifer properties on the synthetic heterogeneity of aquifer according to its weight coefficient. So the HIS of aquifer could be successfully used to deal with spatial heterogeneity of aquifer, and provide foundation for studying contaminant transport.%传统模型主要侧重于通过含水层的某一单一属性来定性或半定量化表征其非均质性,无法对含水层综合非均质性进行定量描述.引入非均质综合指数(HSI)这一概念来定量化表征含水层多个属性的综合非均质性.其具体的计算过程主要包括以下3个步骤:利用Markov原理建立含水层沉积微相分布模型；通过相控建模原理,利用改进的序贯模拟法建立含水层属性参数分布模型；通过熵权法计算出上述各个含水层属性模型的权值系数,并根据此系数对模型进行叠加,从而求得含水层非均质综合指数.将该方法应用于华北平原栾城地区,对该区的冲洪积扇含水层非均质性进行研究,计算结果表明:沿滹沱河冲洪积扇半径方向的沉积微相变化平缓、含水层参数连续性较好,故其非均质性较弱,HSI为0.74～0.95；冲积扇相互叠加区域沉积微相变化剧烈,属性参数具有较强的空间变异性,故其具有强烈的非均质性,HSI为0.38～0.65,这表明在该研究区内沉积环境对含水层非均质性起着控制作用.非均质综合指数能够在考虑多项含水层属性的基础上,定量化表征含水层的综合非均质性及各属性对综合非均质性的影响,并为后续的污染物运移研究提供基础.