海水入侵指标对比分析与评价—以珠江口地下水含水层为例

Comparison of indicators for the assessment of saltwater intrusion in coastal aquifers——taking aquifers in Pearl River Estuary as an example

  • 摘要: 合理评价海水入侵对于地下水含水层管理和居民生活健康有着重要的意义。当前海水入侵评价应用较广泛的为包含单一因子和基于统计分析的多种水化学方法。本文综合阐述了海水入侵评价中所用的水化学指标、原理与方法,包括在国内评价体系中少见的一些方法,并以珠江口地下水含水层为例,对比了各种指标的有效性,评价了各类方法的优缺点以及在实际应用中可能产生的问题。结果显示,以Cl-和TDS作为简单直接的单因子可以快速评价海水入侵,尤其对于大范围的海水入侵评价十分有效。而和Ca2+,HCO3-,SO42-等变化有关的指标具有地域性,在研究区对海水入侵的指示并不是十分敏感。在复杂评价因子中,与离子交换有关SARBEX以及GQISWI与Cl-相关性较高,可以较好的指示海水入侵及水岩相互作用。经过分析,受到地下含水层和地表水道双重介质入侵的影响,研究区海水入侵范围在过去几个年代有向北推进的趋势。本研究对于高速经济发展下的沿海地下水含水层管理和评价有重要的指导意义。

     

    Abstract: Saltwater intrusion (SWI) represents a threat to coastal aquifers worldwide by rendering groundwater quality not viable for its intended purposes.Therefore, understanding and assessing the impact of SWI effectively is indispensable for the aquifer management and the health of residents.Nowadays, SWI assessment from hydrogeochemical aspect generally includes single factor and multiple indexes.In the study, taking aquifers in Pearl River Estuary as an example, the paper comprehensively expounds the hydrochemical indicators and their principles including the methods which are seldom used in China.Then the effectiveness, time consumed and economic cost of the variable indicators are compared and the associated practical problems are evaluated.The results indicate that Cl- and TDS indicators are simple ways that could be used as effective direct single factors in the SWI evaluation, especially for large-scale.Meanwhile, the Ca2+ related indicators are not sensitive to separate the freshwater and saltwater in the study domain.Among the complex factors, SAR, BEX and GQISWI are highly correlated with Cl- and could illustrate the ion exchange in the SWI process.The research provides a comprehensive review of most of the indicators which commonly used in assessing the dynamics of SWI and compares their potential impacts.The paper as well as provides an effective way for informed impact assessment and planning for sustainable exploitation of coastal aquifers.

     

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