Underground Water

 Groundwater is water that is contained in layers of soil or rocks below the surface of the soil. Groundwater is one of the water resources. In addition to river water and rain water, ground water also has a very important role, especially in maintaining the balance and availability of raw water supplies for domestic (domestic) and industrial purposes. In some areas, dependence on clean water and groundwater supplies has reached ± 70%. Actually below the surface of the ground there is a collection of water that unites the collection of water that is on the surface.

 The location of ground water can reach several tens or even several hundred meters below the earth's surface. Some layers of rock escaped water or are usually called permeable and some are not escaped or impermeable to water which is commonly called impermeable. The escaped water layer, for example, consists of gravel, sand, pumice, and cracked rock, while the impervious layer consists of marl and clay or clay. Actually clay can absorb water, but after it is saturated with water, this type of soil can no longer absorb water.

 Ground water in this earth is far greater than the amount of surface water. 98% of all water on land is hidden beneath the surface of the soil in rock pores and granular materials. There are two sources of ground water, namely:

1. Rainwater that seeps into the soil through pores or cracks in rock formations and finally reaches the ground water level. 

2. Water from surface water flows such as rivers, lakes and reservoirs that seep through the soil into the saturated lane. 

 Rainwater and surface water will infiltrate first to the zone of aeration and then sink deeper into the water saturation zone and become ground water. Ground water is one of the facets in the hydrological cycle, which is an event that always repeats itself in the sequence of steps that water passes from the atmosphere to the earth and back to the atmosphere.

 From the hydrological cycle, it can be understood that ground water interacts with surface water and other components involved such as topographic forms, types of overburden, land use, cover vegetation, and humans on the surface. Ground water and surface water are interrelated and interact. Every pumping action, pollution of ground water will give a reaction to surface water, and vice versa. To form ground water itself needs a long process, from the hydrological process itself and from the process of water entering through the pores of the soil such as rocks to tens or even hundreds of meters above ground level.