Groundwater

Meteoric Groundwater:

Groundwater can be describe as the amount of water that is used to saturate the parts of Earth and helps to fill all the available spaces. Set behind the others,the most common type of ground water is meteoric water. This is the type of groundwater that freely circulates as an important portion of the water cycle. This meteoric water is generally soaked deep down into the ground by the process of precipitation (rain water or droplets) or through streams and lakes. There it remains for sometimes and then comes up to the surface of the ground. At first, it was thought that the hard and porous ground have enough space to hold up all the meteoric water.

The available space may present in different form; like those in the grains of sand or in the pebbles. For example, if the large sheet of ice starts melting that is present over the Antarctica, we observe a huge volume of glacial water comes down with stream flow.When this flow slows down, it deposits some volume of its water over the ground surface. The water flow also carries some amount of small rocks and sand grains that starts depositing over the ground surface.

The same case appears to that day, weather on a minute scale, when the river or a stream over loaded from sediments comes down from the mountains or valley and flows over the surface of a flat surface, it reloaded some of its sediments and formed a fan shape like area. Also when this water moves and slow over the surface, some of its rocks lack behind and minerals rich area. This case is similar for the cemented sediments.The cemented sediments contains a vast variety of small pores that are used for holding water in their surface. The main reason behind this phenomena is that, the pores are not always filled with chemical material and sometimes the original pores of the rocks may dissolved due to continuous percolating groundwater. To the conclusion, some sandstone as much as porous so they become appear as the grains of sand with a hard boundary.

Difference Between Porosity and Permeability:

Therefore, we can say that the total portion of the rock or a sediment, consists of many empty spaces. As compared to sediments rock,the crystalline rock is very hard and solid, Except basalt, which is the form of solidified molten lava and filled with large number of rocky material and half of its volume has empty space. This portion of porous rock can be known by a term called porosity. One thing should be keep in mind about porosity and permeability. Permeability, simply can be defined as a phenomena which indicates the amount of water that flows easily from a surface material and it is quite different from the porosity. While porosity can be better explain by saying that the phenomena that holds the maximum amount of water in material body.

We observe that a large amount of water overflows from a water saturated body, when it placed in a very dry place. But sometimes it remains in the same material body. The water forces simply known as surface tension holds the droplets of water there. Cohesion is another force that holds water molecules and it is the same force that helps the water to reach higher altitudes like water moves from roots to the branches and leaves of the plants. The relative amount of stored water is totally different from body to body. It depends upon the surface and material of the rock. Some rocks are highly porous retains a large amount of water, while some are less porous than others.