Sketch how groundwater accumulates and occurs in rock and sediment. Distinguish porosity and permeability, providing examples of materials with high and low values of each. Discuss the ways we use fresh water; and, which four uses consume the most water. Summarize the location, characteristics, and importance of the Ogallala aquifer. Summarize the water balance for the aquifer and how water levels have changed in the last several decades.

The rocks are aggregates of minerals and are formed under different conditions. These rocks are associated with various geological features such as fractures, cleavages and fault. The interconnected pore spaces are extended deep down into the earth's crust. When water flows over these region, it flows through the cracks and fractures of rocks and percolates deep into the ground, and eventually mixes up with the water, which is commonly known as then groundwater. This is how groundwater accumulates in the rocks.

The porosity is defined as the property by which the pore spaces (voids) in the rocks has the ability to store water in them. For example, Sandstone. On the other hand, permeability is defined as the property by which the water flows down into the groundwater through the pore spaces. For example, granite.

The water is highly essential in day to day use. The freshwater is basically used for drinking purpose, washing clothes, irrigation, and bathing.

The consumption of water is mostly takes place due to the following reasons-

(1) For drinking purpose

(2) For house hold use such as washing dishes, bathroom use, bathing.

(3) For industrial purpose

(4) For irrigation purpose

The Ogallala aquifer is usually referred to the shallow aquifer that is located at the great plains of the US. It is surrounded by the presence of sand, clay, silt and some gravels. It is a well known for its large production of water on which the people of US are dependent on, but over the last few years, the water in this aquifer are gradually depleting. This would have large impact on the people of US.

In an aquifer, the water in added through the percolation or by the process of infiltration in the recharge area. And this water is extracted through pumping, and springs. In simple words, it can be written as

Amount of Precipitation = amount of evapo-transpiration + amount of Run-off + amount of Recharge.