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FLOW AND WATER QUALITY OF UNCONFINED GROUNDWATER IN TAKAMATSU PLAIN

高松平原无约束地下水流量与水质

基本信息

批准号：
15560444
负责人：
KAWAHARA Yoshihisa
金额：
$ 2.37万
依托单位：
HIROSHIMA UNIVERSITY (2004)Kagawa University (2003)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

The present study aimed to understand the distribution of flow and quality of unconfined groundwater in Takamatsu plain and to detect the source of nitrate nitrogen in groundwater in the left bank area of Koto River, where high nitrate concentration has been measured all the year round. Major results in this study are summarized as follows.1.Measurement of unconfined groundwater quality at 65 stations and the cluster analysis of the Stiff diagrams demonstrated that the groundwater quality can be classified into four categories, one of which shows anthropogenic effects.2.Intensive field measurement in the target area that locates on the alluvial fan of Koto River, the information on the land use and the fertilizers used along with the analysis of major anions and cations attributed the nitrate contamination in the area to the fertilizers.3.The nitrogen isotope ratio at several locations showed higher value than that reported in the past studies. The isotope-ratio analysis taking account of the effect of ammonia volatilization was then applied to indicate that both organic and inorganic fertilizers are responsible for the high concentration of nitrate nitrogen, which agreed well with the information of the fertilizers.4.Two dimensional numerical simulation of confined groundwater, which accounts for the interaction between confined and unconfined groundwater, showed that the confined aquifer receives a lot of unconfined groundwater in the target area and hence that the improvement of fertilization is necessary to prevent nitrate contamination in the confined groundwater.

本研究旨在了解高松平原地下水的流量和水质分布，并在江东河左岸地区，那里的硝酸盐浓度一直测量常年高地下水中的硝酸盐氮的来源进行检测。主要研究结果如下：1.通过对65个地下水水质监测站的地下水水质监测和Stiff图聚类分析，将地下水水质分为4类，其中一类是人为因素造成的。土壤氮同位素比值的研究结果表明，土壤氮同位素比值的变化趋势与土壤氮同位素比值的变化趋势一致，土壤氮同位素比值的变化趋势与土壤氮同位素比值的变化趋势一致。考虑氨挥发影响的同位素比值分析表明，有机肥和无机肥是造成土壤硝态氮浓度高的主要原因，与化肥本身的信息吻合较好。4.承压水二维数值模拟，考虑承压水与非承压水的相互作用，结果表明，承压含水层接受了大量的地下水，因此，改善施肥是必要的，以防止硝酸盐污染的承压地下水。