含水层中弥散系数的尺度效应

Scale Effect About Dispersion Coefficient in Aquifers

为确定研究区含水层的弥散系数,进一步开展咸水体运移的数值模拟,根据研究区的地质背景和水文地质条件,针对含水层中咸水体分布格局设计并开展了示踪试验。利用试验获得的数据初步分析了咸水体垂向和横向运移特征,提出了依赖于单尺度示踪试验结果推求多尺度下弥散系数的内推-外延法,据此计算了试验尺度上的弥散系数。示踪试验结果直观地反映了咸水体对抽水井中氯离子质量浓度的影响,确定了试验尺度上的横向弥散度为7.42m,垂向弥散度为41.4m。基于弥散方程的解析解,采用半程拟合的方法进行尺度效应的分析,确立了横向及垂向弥散度与试验尺度关系分别为y=0.007 5.e0.129 3x和y=0.102 9e0.049 2x。根据上述定量关系可进行同类地区相似条件下的弥散系数计算和尺度效应分析,从而为进一步开展咸淡水交互地带水盐运移的模拟和预测提供参数基础。

In order to determine the dispersion coefficient and simulate the saline water migration, a tracer test has been designed and carried out aim at the distribution of the saline water in the aquifer, which based on the geological background of the study area and the hydrogeologic condition. With the test data, the vertical and lateral migration characteristics of the saline water were analyzed preliminary and a push-extension method was present to predict the dispersion coefficient or dispersity under the multi-scale dependent on single-scale tracer test results. The tracer test illustrated the different effects of the saline water to the pumping well and attained the longitudinal dispersity is 7.42 m and latitudinal dispersity is 41.4 m. From the analysis of the solution of the dispersion equation, scale effect about the desperty has been discussed, and the relation has been set up to be as y = 0. 007 50.129ax and y = 0. 102 9e0.0492z, respectivity. These quantitative relation are suitable for the dispersion coefficient calculation and the scale-effect analyzation, thereby this will provide a further data basis for the simulation and prediction on the water-salt transport characteristics.