Water distribution on Earth
Its distribution is broadly similar to that of surface river water, but it is easier to store in hot and dry climates because groundwater storage are much more shielded from evaporation than are dams.
For example, as much as a quarter of Australia's limited renewable fresh water supply is found in almost uninhabited Cape York Peninsula.
[15] The areas of greatest concentration of renewable water are: The oceanic crust is young, thin and dense, with none of the rocks within it dating from any older than the breakup of Pangaea.
Since the low density rocks of the continental crust contain large quantities of easily eroded salts of the alkali and alkaline earth metals, salt has, over billions of years, accumulated in the oceans as a result of evaporation returning the fresh water to land as rain and snow.
This historically aided the development of many of the great civilizations of ancient history, and even today allows for agriculture in such productive areas as the San Joaquin Valley.
Consequently, available nutrient levels in Australian and Southern African soils tend to be orders of magnitude lower than those of similar climates in other continents, and native flora compensate for this through much higher rooting densities (e.g. proteoid roots) to absorb minimal phosphorus and other nutrients.
Even for other Australian rivers, a storage three times as large is needed to provide a third the supply of a comparable climate in southeastern North America or southern China.
It also affects aquatic life, favouring strongly those species able to reproduce rapidly after high floods so that some will survive the next drought.
Although soils in tropical Australia and southern Africa are even poorer than those of the arid and temperate parts of these continents, vegetation can use organic phosphorus or phosphate dissolved in rainwater as a source of the nutrient.
In cooler and drier climates these two related sources tend to be virtually useless, which is why such specialized means are needed to extract the most minimal phosphorus.
An estimated 1.5 to 11 times the amount of water in the oceans may be found hundreds of kilometers deep within the Earth's interior, although not in liquid form.
[23] Direct evidence of the presence of water in the Earth's mantle was found in 2014 based on a hydrous ringwoodite sample included in a diamond from Juína, Brazil.
[25] Molecular water (H2O) is not the primary water-bearing phase(s) in the mantle, but its high-pressure form, ice-VII, also has been found in super-deep diamonds.
