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深层孔隙水的咸水下移是滨海地区普遍存在的环境地质问题,目前对其形成和循环运移机理争议较大,是当今水文地质理论研究的重要内容之一。作者通过地下水资源的系统调查研究,利用地下水同位素的采样测试成果并结合地下水含水层结构初步分析了深层水的补给运移,并根据地下水的历年开采量的调查和水位、水质的动态变化研究了地下水动力场、化学场的演化特征。作者认为,深层水氚含量较80年代含量高,绝大部分含量在4～10TU。在补给条件好的古河道上游地区,多在10～20TU。这表明深层地下水经过几十年的大规模开采,水动力条件改变,水平迳流和垂向越流均有所增强,促进了地下水循环,而以近50年来大气降水渗入补给的地下水占优势。由于几十年深层地下水的超量开采,天津市南部平原区已形成地下水位的常年漏斗区。由于浅、深层地下水巨大的水位差,深层淡水已受到上部咸水下移的影响。地下水的主要常量组分TDS、Cl-、SO42-在南部平原区表现为含量总体升高的趋势,在地下水的集中开采区表现的更为突出,已经导致了天津市中南部平原第Ⅱ含水组淡水水质的咸化,地下水环境正在不断恶化。
The descending of salt water in deep pore water is a common environmental and geological problem in the coastal area. At present, the mechanism of its formation and circulation is quite controversial, which is one of the important contents of the present hydrogeological research. Based on the systematic investigation of groundwater resources, this paper uses the sampling results of groundwater isotopes to analyze the recharge and transport of deep water in combination with the groundwater aquifer structure. Based on the investigation of the exploitation of groundwater over the years and the dynamic changes of water level and water quality Groundwater hydrodynamic field, evolutionary characteristics of chemical field The author believes that deep water tritium content higher than the 80’s, most of the content of 4 ~ 10TU. In the upper reaches of the ancient river supply conditions are good, more than 10 ~ 20TU. This indicates that after decades of large-scale exploitation of deep groundwater, changes in hydrodynamic conditions, horizontal overcrowding and vertical overcurrent have been enhanced, contributing to the groundwater cycle, while groundwater recharged by atmospheric precipitation dominated over the past 50 years. Due to the over-exploitation of deep groundwater for several decades, the perennial funnel zone of groundwater level has been formed in the southern plain of Tianjin. Due to the huge water level difference between shallow and deep groundwater, deep fresh water has been affected by the downward movement of the upper saltwater. The main constant components of groundwater, TDS, Cl- and SO42-, show an overall increasing trend in the southern plains. They are more prominent in the centralized exploitation of groundwater and have led to the development of the Second Central Aqueous Unit of the Central-Southern Plains in Tianjin Freshwater salinity, groundwater environment is deteriorating.