泾惠渠灌区地下水化学特征及其对不同水源灌溉的响应

Chemical Properties of the Groundwater in Jing Huiqu Irrigation District and Their Response to Irrigation Using Water from Different Sources

为研究泾惠渠灌区地下水水质状况及其对不同水源灌溉的响应,对桥底镇地下水进行系统采样,分析了泾惠渠灌区地下水基本特征、地下水化学成分形成原因和不同灌溉水源区地下水的暂时性变化规律。结果表明,泾惠渠灌区桥底镇浅层地下水以Na+Mg—HCO_3+SO_4+Cl类型为主,地下水环境为碱性咸水,影响TDS的主要离子排序为SO_4^(2-)>Cl^->Ca^(2+)>Mg^(2+);蒸发浓缩作用、阳离子交换作用和溶解沉淀作用是影响地下水化学成分形成的重要因素;井灌区地下水中各离子质量浓度均比渠灌区高,Ca^(2+)在2种类型区域的量有显著差异且年变异系数最大;引起Ca^(2+)和Na^+暂时性变化的因素是灌溉和降雨。灌区灌溉应在保证水量的情况下优先选择渠水灌溉,降雨集中期和灌溉期要加强灌区地下水水质的管理工作。

This paper investigated the response of chemical properties of groundwater in Jing Huiqu irrigation district to irrigation using water from different sources. Groundwater at town of Qiaodi town were sampled for hydrochemical analysis, and the chemical compositions and their temporal changes in the areas irrigated using different waters were studied. The results showed that the hydrochemistry of the samples was dominated by Na ＋Mg—HCO3＋SO4＋Cl and the shallow groundwater was alkaline. The significant of ions that affect TDS was in order of SO4^2-Cl^-Ca^2＋Mg^2＋. The factors that affect the chemical composition of the groundwater was evaporation, cation exchange and dissolution-precipitation. The concentrations of all ions in the well-irrigation areas were higher than that in the canal-irrigation areas. The concentration of Ca^2＋in the two areas irrigated with groundwater and canal-surface water differs considerably. What led to the temporal changes in Ca^2＋and Na^＋ was irrigation and precipitation.Therefore, canal-water irrigation should be considered firstly if it is available, and the groundwater quality management should be improved when rainfall is intensive or when irrigating the fields.