phreatic fluctuation

例句：

1. 1. The phreatic aquifer is the source of many rivers.
   含水层是许多河流的源头。
2. 2. The hot springs are popular for their healing properties.
   温泉因其疗愈特性而受欢迎。
3. 3. Mineral water is often considered to be healthier than tap water.
   矿泉水通常被认为是比自来水更健康的。