It´s formed from rainwater. Once it has rained, the water infiltrates into the subsoil and descends until it’s retained in an impermeable layer. This subsoil layer allows for the storage of water, which completely occupies or saturates the pores or holes in the ground, thus forming aquifers.
In contact with Dr. Jorge Santa Cruz, director of the Water Resources Division of the Inter-American and Argentine Association of Sanitary and Environmental Engineering (AIDIS), we talked about the origin, its relevance, and the main characteristics of groundwater. At first, it can be said that groundwater is the water that exists under the surface of the ground. Specifically, it’s the water located below the water table, and that is completely saturating the pores and cracks of the ground.
“Groundwater is constantly renewed by nature, thanks to the refilling process. The refill is part of the hydrological cycle, and corresponds to the water that, due to the action of the force of gravity, infiltrates through the soil until it reaches a saturated zone”, defines Dr. Santa Cruz. It can either flow to the surface naturally through springs or riverbeds, or discharge directly into the sea or bodies of water such as lakes and lagoons. It can also be exploited through wells, galleys, and other types of catchments.
The origin of these refills generally comes from precipitation, but it can also happen from surface runoff and watercourses, especially in arid climates, from nearby aquifers. Like sponges, the geological formations of the subsoil, during infiltration, store the groundwater. In conversation with the director of the water resources division of AIDIS, he explained to us that an aquifer, then, is a geological formation that stores and transmits water in significant quantities, so that it can be extracted through catchment works.
The physical characteristics of the surface that influence the characteristics and behavior of groundwater are altitude, gradient of the land, permeability, geology, soils, and the presence of vegetation. Secondly, the climatic and environmental conditions determine a certain precipitation pattern, runoff, temperature and initial soil humidity.
Groundwater undergoes changes in its composition, which is why its protection includes a set of activities and provisions aimed at preserving both quality and quantity. “For the purpose of preserving the quality of groundwater, some countries use strategies to define protection zones around catchments, such as; drilling, springs, among others”, defines Jorge Santa Cruz. The use of territory and any activity that implies a risk of contamination is limited. The restrictions are usually more severe in the vicinity of the catchments and dissipate as the distance from them increases.