Hydrogeological Diagram of the Pingtung Plain
The contour lines on the map show that below the Ailiao Fall, many alluvial deltas fill the Pingtung Plain. The thick gravel on the plain acts like a huge sponge that absorbs water into the ground. Water sometimes flows on the surface and sometimes underground to lowland areas. Thus, the plain has plenty of water. Coastal land sinkage, caused by over-extraction of groundwater and insufficient replenishment of groundwater upstream, causes the sea to flow inland and salinize the groundwater.
The best way to supplement groundwater is by using gravel and coarse sand areas where river and rainwater can be easily absorbed. Man-made lakes or deep wells in areas with good permeation allow river water to supplement groundwater. This will prevent land from sinking and provide a sustainable source of groundwater.