Oceanography
How does water reproduce its self under the ground.
Groundwater (water under the ground) does not reproduce itself (you can't get something from nothing). Groundwater is replenished by rainfall. Many people think groundwater occurs in underground rivers or lakes, but it actually occurs in bodies called aquifers. Aquifers form in sediments (like sand or gravel) that have space between the grains. You can make your own aquifer, fill a jar with pebbles, then fill it up with water afterwards. Drinking water in many places comes from wells drilled down into an aquifer just like that. To get back to your question, when it rains much of the water seeps into the ground and eventually comes to rest in an aquifer. Unfortunately aquifers usually take a long time to replenish, we must be careful how much we remove to drink!