When digging a well, there are sometimes springs. It is said that this is an underground river. What is an underground river? Is it flowing? Where is the way out?

The spring hole dug is not necessarily an underground river, but also an underground aquifer (structural belt or aquifer), and the underground river is a hidden karst cave.

With the increase of atmospheric precipitation, the groundwater level will rise and fall, and groundwater will appear in low-lying areas. Due to the continuous replenishment of atmospheric precipitation, groundwater has been flowing.

Underground rivers are cracks between strata. With water, it will flow to form an underground river. The water outlet generally flows directly into the river, and a small amount into the sea. The spring eye is a hole between the underground river and the surface of the earth, and the water surges upward.