鄂尔多斯白垩系盆地地下水流动系统驻点的理论与实际意义

Theoretical and practical meaning of stagnant points of groundwater flow system in the Cretaceous Basin of the Ordos Basin

地下水系统理论、达西定律和泰斯公式是水文地质学的三大支柱理论,地下水流动系统理论较好地刻画了盆地尺度地下水的循环特征,是指导区域地下水勘查与合理开发利用的重要工具。迄今为止,对地下水流动系统中驻点的形成机理和特征的认识一直停留在定性分析阶段,在实际的大型盆地地下水流动系统中发现并证实驻点存在的实例也不多见。以鄂尔多斯白垩系盆地北部的二号剖面为例,利用双Packer系统获取的不同深度地下水位、水化学和同位素的分层数据,采用水动力学、水化学和放射性碳同位素等综合方法,以实际资料证实并发现在大型盆地深层地下水流动系统中驻点的存在,但这个驻点并不是一个点,而是占据了一定的区域;理论研究认为驻点附近地下水的溶解性总固体较高,实际情况不一定如此,也可以是较低矿化的水,它取决于含水介质中可溶盐量的多少。该项成果进一步完善了地下水流动系统的理论,具有重要的理论与实际意义。

Groundwater flow systems, the Darcy＇s Law and the Theis formula are the major theories of hydrogeology. The groundwater flow system theory is the guiding theory for groundwater investigation, especially for regional groundwater investigation. It is a powerful tool for identifing hydrogeological conditions. Stagnant points are the identifiers for the division of shallow, intermediate and regional groundwater flow systems and have been proved to be present theoretically. So far, stagnant points have not been found in reality. In this paper, stagnant points were found in a cross section in the Ordos Basin, using radioactive carbon and hydraulic methods. This paper drawn the conclusion that stagnant points are present, they occupy a certain area and TDS around the stagnant points are not high. The results are the basis for further analyses and improvement of groundwater flow systems.