Groundwater is water that has seeped into the ground, filling the soil pore spaces between sand or gravel, as well as fractures and voids within the underlying rock. Around 30% of the world’s readily available freshwater is groundwater, making it one of our most crucial natural resources.
Groundwater is replenished through surface water infiltration, such as rain or snow. When the groundwater saturates the soil pore spaces and fills the fractures and voids in rocks, it creates a saturated zone. The upper surface of this saturated zone is known as the water table, which fluctuates with seasonal changes and water extraction. For instance, the water table may rise during the winter months when rainfall is abundant and drop during the summer or due to groundwater pumping.
Interestingly, the water table doesn’t always follow a flat or horizontal line but generally mirrors the topography of the land above it.
When groundwater is stored in porous rock, gravel, or sand layers capable of producing a usable volume of water, it forms what we call an aquifer. There are two main types of aquifers:
- Unconfined Aquifer (also known as a water table aquifer): This type is located directly below the surface with a permeable layer above it. It is recharged by surface water, such as rainfall or streams. The water table in an unconfined aquifer is at atmospheric pressure and is more vulnerable to seasonal fluctuations.
- Confined Aquifer: A confined aquifer is situated between layers of low permeability material, such as clay or silt, which restrict water movement. In this case, groundwater is stored under pressure and is less influenced by surface water variations.
Groundwater is a vital resource for farms and orchards, and its proper management ensures sustainable use while maintaining the health of the surrounding environment.
Jessica Hunter
Environmental Consultant