Aquifers

How Aquifers Work

Aquifers are underground layers of water-bearing rock that store and transmit groundwater. They are critical to maintaining the water supply for many regions, including Comal County. Here’s a closer look at how aquifers function:

Recharge: Aquifers are replenished through a process known as recharge, which occurs when rainwater and surface water seep down through fractures and faults into permeable rock layers in the aquifer. Recharge areas are often located in higher elevations where water can easily infiltrate the ground. Recharge rates vary drastically between the Edwards and Trinity aquifers. Whereas the Edwards can recharge quickly after heavy rain, it can take years for the Trinity aquifer to recharge as is has lower permeability and porosity compared to the Edwards aquifer. (Here is where you could use a map of the contributing, recharge, and artesian zones as well as a cross section of the Edwards and Trinity aquifers)

Storage: The water in an aquifer is stored in the void spaces between rocks. – The capacity of an aquifer to store water depends on its porosity (the amount of open space between particles) and permeability (the ability of water to flow through the material).

Movement: Groundwater within an aquifer moves slowly, typically flowing from areas of high pressure to areas of lower pressure. This movement can be influenced by gravity, geological formations, and human activities such as well pumping. 

Discharge: Aquifers discharge water into springs, rivers, and lakes, maintaining the flow of surface water bodies. This process helps sustain ecosystems, especially during dry periods when surface water is scarce. The interrelation between underground aquifers and above ground springs, rivers, and lakes is key to a healthy aquifer system.