ABSTRACT The demand for fresh groundwater in the Jaffna peninsula in northern Sri Lanka, has been increasing as the only water source for domestic and agricultural needs. Isotopic and hydro-chemical assessment on groundwater recharge and quality was done with the objective of assisting groundwater management plans. Water samples were collected in pre and post monsoon periods for isotope analyses (2H, 18O and 3H) and major ions. Isotope data provide evidence that the groundwater is predominantly recharged by inter-monsoon (convectional) and North-East monsoon rains. Different residence times of shallow groundwater were found. The study revealed that the groundwater quality is mainly deteriorated due to dissolution of geogenic elements. However, in some instances, seawater intrusion and evaporation have caused lowering of groundwater quality. More saline groundwater is found in deeper levels in the karstic limestone aquifer system. Fresh water is available in coastal sandy aquifers in the eastern part of the peninsula. The impact of rainfall variations and agricultural activities are contributory factors for producing variations in the quality of groundwater. The current study suggests artificial groundwater recharge for the development and utilization of groundwater resources through small scale tanks/reservoirs or ponds in the areas where direct rain recharge occurs.

中文翻译：

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斯里兰卡北部贾夫纳半岛天然水的同位素和化学评估，用于地下水开发方面

摘要斯里兰卡北部贾夫纳半岛对淡水的需求一直在增加，成为满足家庭和农业需求的唯一水源。对地下水补给和水质进行同位素和水化学评估，目的是协助地下水管理计划。在季风前后收集水样用于同位素分析（2H、18O 和 3H）和主要离子。同位素数据提供的证据表明，地下水主要由季风间（对流）和东北季风降雨补给。发现浅层地下水的停留时间不同。研究表明，地下水水质恶化主要是由于地质要素的溶解。然而，在某些情况下，海水入侵和蒸发导致地下水质量下降。在岩溶石灰岩含水层系统的更深处发现了更多的含盐地下水。半岛东部沿海含沙含水层有淡水。降雨量变化和农业活动的影响是造成地下水质量变化的促成因素。目前的研究建议在直接雨水补给的地区通过小型水箱/水库或池塘进行人工地下水补给，以开发和利用地下水资源。