Did You Know?

Part of the precipitation penetrates the Earth infiltration . The permeated water will either flow in the course of inter layer water currents of the Earth inter flow , or as deposits , form subterranean water basins.

These water basins may form in the following ways:

1 - in the fine layer of sands which are formed from the decomposition of a mass of hard or unpermeative stones surface water basin,

2- in a permeative layer of Earth which is located on an unpermeative one free normal water basin,

3 - in the alluviums of an extensive plain alluvial plain water basin,

4- in a permeative layer which is located between two unpermeative layers and has run to the surface of the Earth as a result of erosion. Depending on the condition of water under the ground and also permeation of subterranean layers, underground waters may run on the surface of the Earth in a vriety of ways.

A- escaping little permeative lands :

1- springs,springs are in fact underground waters which flow on the surface of the Earth and in most cases they are formed from rain waters and / or waters resulted from the melting of snow,which penetrate into the ground and flow and stay for some time in the hollow spaces there mineral cold or warm waters are not considered among these waters . How water leaves the ground is a factor which distinguishes three types of springs :

1-1- flowing springs,in these kinds of springs,water immediately runs along the profile of slopes towards valleys,

1-2- basin springs , in these springs water fills a natural basin , before overflowing along profile of slopes,

1-3- lagoon springs,here water leaves the ground through a more or less thick layer and changes the surrounding land into a lagoon.

2- acqueducts , these are canals which are dug under the ground from plains towards mountains so that they cross water bearing basins and drain their water . To dredg acqueducts,some wells are usually dug every 30 to 40 meters in their course.The distance from the source of the acqueduct to the last well,known as the mother well,varies between a few meters to a few kilometers. Historical evidences indicate that Iranians were the first to make aqueduct.

B - escaping high permeative lands : in this case water leaves the ground in the form of springs more in hard lands full of fractures or passages.

C - escaping fractures : in this case water leaves fractures.These fractures might either be in a simple crack form which are known as crack,or in the form of a crack accompanied by a displacement of layers known as fault.

D - Escaping through digging wells : in this method water is drained by boring a hole in the ground which gets to the water basin . The drain of water from wells is usually carried on by using auxiliary equipments such as pumps.However,there is also another kind of well,known as Artesian it is a well board down to the point,usually at great depth,at which the water pressure is so great the water is forced out of the surface.

Adapted from the book : "Water"