What is groundwater?

What is groundwater?

What geologists call the "rock-broken zone" refers to the porous outer part of the Earth's crust. This section of pores or openings is located at different locations at different depths below the surface. Not all of the water present in these openings is called groundwater. Some of the water is stagnant near the surface in the form of soil moisture. Just below this layer of openings is a layer of openings that are partially filled with water that is attached to the material in or around the openings. This layer of openings is above what is called the capillary rim, which in turn is above the water table.

The water table is the upper limit of the underground reservoir and is a layer of material whose pores are filled or saturated with water. Through capillary action (i.e., the tendency of water to rise in a tube when the lower end of the tube is below the water surface), some additional water is drawn into the partially filled openings just above the water table, forming the capillary rim. See Figure 1-2.

The water level between the water table and the surface constitutes the aeration zone. The area below the water table, where the pores are filled with water, is called the saturated zone. Only water that is actually in the saturated zone is called groundwater. The rest, along with groundwater, is called groundwater. The stratum in which the saturated zone lies is called an aquifer.