Where does new water come from?

Question

So we know that water is recycled from ground to air to ocean, vice versa or goes into ground to add to the water table etc., water also comes from glaciers into rivers but that is also recycled water in form of rain or snow etc..I read few days back that there are oceans under ground….are we just recycling water that was ever existing? If not, where does new water come from?

In: Physics

Answer 1

You were more or less right in that, the water cycle (where it is recycled) is the correct way of looking at it. All the water we use was a part of the cycle, somewhere.

However, a key point in this is that, fresh water–the water we drink and use for most things–is only about 3% of the Earth’s water. 97% is in the ocean. Now, water can evaporate off of land, but it can also evaporate off the ocean. This produces rain clouds which fall over both land and ocean, returning non-salt water to land which soaks into the earth, and if sufficiently far and given some conditions, will gradually form rivers as it travels back to the ocean at a lower point.

So clouds bring the water up, soaks the earth, then water flows back down.

However the water cycle is a little more complicated than that, as you also have glaciers and ice (also fresh water–in fact most of the remaining 3%), which NORMALLY would both lose and gain mass through periods of warming and cooling of the Earth, either on the timespan of years, or thousands of years. But year to year, they’re NORMALLY balanced, but nowadays they lose mass more than they gain, so more water is entering the cycle.

In addition, you have aquifers. Water deposits can be located deep underground due to the nature of the rock layers of the Earth’s crust. This is also fresh water, and can be enormous in amount. The US has such an aquifer that has been used for something like 65% of the water demands of its states, especially around the Great Plains and normally dry areas such as Texas. Legitimately the water falling on the land and resupplying the rivers is not enough to meet demands, so more water is coming in from depleting these aquifers (they DO regenerate, but very slowly, so there will indeed come a future point where they are just depleted, and since that fraction of a 3% doesn’t significantly effect the rain cycle, you will not get more rain to compensate).