underground water divide

例句：

1. 1. The underground water divide is acritical factor in determining the distribution of freshwater resources.
   地下水分界线是决定淡水资源分布的关键因素。
2. 2. The constructionof the underground water divide has been along-standing issue for many communities.
   地下水分界的建设一直是许多社区长期存在的问题。
3. 3. The underground water divide is often usedas a boundary between different regions to regulatewater usage and conservation.
   地下水分界线通常被用作不同地区之间的边界，以调节水资源和保护环境。