main water table

例句：

1. 1. The main water table is located at the depth of 20 meters below the surface.
   主水层位于地表以下20米处。
2. 2.The research team used a special method to map the main water table in the region.
   研究团队使用了一种特殊方法来绘制该地区的主水层地图。
3. 3. Main water tables are often found in areas with high groundwater levels.
   主水层通常出现在地下水位较高的地区。