Abstract:

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(HSI) 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 HSI 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 HSI was 0.74-0.95; while in the superstition zone of alluvial-pluvial fan, the heterogeneity of aquifer was stronger, HSI was 0.38-0.65. The sedimentary environment had significant effect on heterogeneity of aquifer. Therefore based on considering many aquifer properties, HSI 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 HSI of aquifer could be successfully used to deal with spatial heterogeneity of aquifer, and provide foundation for studying contaminant transport.

Key words: aquifers, entropy weight, heterogeneity synthetic index, sequential simulation, alluvial-pluvial fan