The thermal waters of the Island of Ischia, an active volcano located in Southern Italy, are widely used for supplying numerous spas. Groundwater withdrawals occur mainly through wells in the coastal strip. This study explores the impact of withdrawals on the quality of the waters used in thermal facilities, which is required to be constant in terms of composition and temperature by law. For this purpose, specific investigations were conducted including 155 pumping tests, 124 water temperature measurements during pumping tests, 31 temperature and electrical conductivity logs and periodic chemical analysis of the waters of 21 selected wells. By comparing the response to pumping of the aquifer and the quality of the water extracted from the wells, it turned out that the quality of groundwater supplying spas depends not only on natural phenomena (meteoric recharge, seawater intrusion, and rising of deep hydrothermal fluids) but also relies on the island sector where groundwater is pumped and on the pumping method. The distance of the wells from the coast, the type of aquifer formation intersected by the wells, and the field of groundwater temperature of the hydrothermal system strongly affect the aquifer pumping response, determining the quality of water extracted from wells and its variation over time. In Ischia, techniques and regimes of groundwater withdrawals should adapt to the local aquifer pumping response, more than in another hydrogeological context. The concomitant analysis of drawdown, water temperature, and salinity during pumping turned out to be a valuable tool to define the sustainable yield of the single well.

中文翻译：

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含水层抽水响应与活跃热液系统中井提取水质量的关系：以伊斯基亚岛（意大利南部）为例

位于意大利南部的活火山伊斯基亚岛的温泉水被广泛用于提供众多水疗中心。地下水抽取主要通过沿海地带的井进行。本研究探讨了取水对热力设施中使用的水质量的影响，法律要求热力设施在成分和温度方面保持恒定。为此，开展了具体调查，包括 155 次抽水试验、124 次抽水试验期间的水温测量、31 次温度和电导率测井以及对 21 口选定井水的定期化学分析。通过比较对含水层抽水的响应和从井中提取的水的质量，事实证明，地下水供应温泉的质量不仅取决于自然现象（陨石补给、海水入侵和深部热液上升），还取决于抽取地下水的岛屿部门和抽取方法。井距海岸的距离、与井相交的含水层类型以及热液系统的地下水温度场强烈影响含水层抽水响应，决定了从井中提取的水的质量及其随时间的变化。在伊斯基亚，地下水抽取的技术和制度应该适应当地的含水层抽水反应，而不是在另一个水文地质背景下。压降、水温的伴随分析，