四川省简阳市地下水水化学特征及灌溉适宜性

目的]对四川省简阳市地下水水化学特征与灌溉适宜性进行分析和评价,为合理开发该区地下水资源提供科学依据。方法]利用Gibbs图、离子比值系数及多种统计分析方法,研究其浅表层与中深层地下水水化学特征,并将熵权理论与模糊物元法相结合,借助Matlab建立基于熵权的模糊物元模型,对地下水水质进行综合评价。结果]研究区浅表层主要分布淡水,中深层主要为微咸水,由浅至深地下水水化学类型由HCO+3-Ca,HCO+3-Ca·Mg型转化为HCO_3-NaCa,HCO_3·SO_4~-Ca-Mg,SO_4-Na·Ca型。研究区地下水水化学成分主要受控于岩石风化作用,主要受岩盐、方解石、石膏、硅酸盐矿物的溶解及阳离子交替吸附作用的影响。浅表层地下水受人类活动影响比较明显;中深层地下水受深层盐卤水越流混合作用影响较明显。结论]研究区浅表层地下水水质良好,适宜用做灌溉水源,由浅至深,地下水水质逐渐变差,中深层地下水不宜长期用于农业灌溉。

Hydrochemistry Characteristics of Groundwater and Its Suitability for Irrigation in Jianyang City of Sichuan Province

Objective] In order to reveal the hydrochemical characterization of groundwater and provide a theoretical basis for the rational exploitation of groundwater resources, the hydrochemical characteristics and irrigation suitability of groundwater in Jianyang City of Sichuan Province were analyzed and evaluated.Methods] Some research methods such as Gibbs plot, molar ratios and other statistical analysis were employed to study the hydrochemical characterization of groundwater in this area. Combining the entropy weight theory with the fuzzy matter-element method, the fuzzy matter-element model based on entropy weight is established by using Matlab to evaluate the groundwater quality comprehensively.Results] The results indicate that groundwater in the study area is fresh water for shallow aquifers and brackish water for middle-deep aquifers. The shallow groundwater was dominated by the HCO₃-Ca and HCO₃-Ca·Mg types, and the middle-deep groundwater was dominated by the HCO₃-Na·Ca, HCO₃·SO₄-Ca·Mg, SO₄-Na·Ca types. The groundwater in the study area was primarily controlled by weathering of rocks, including the dissolution of minerals(halite, calcite, gypsum and silicate) and ion-exchange adsorption. The shallow groundwater was primarily affected by human activities, and the middle-deep groundwater was affected by mixing from deep brine.Conclusion] The results of comprehensive evaluation of water quality show that the shallow groundwater is suitable for agricultural irrigation, but the middle-deep groundwater is not suitable for agricultural irrigation in the long run. The groundwater quality gradually become worse from shallow aquifers to middle-deep aquifers.