Groundwater: Hidden Resource
Groundwater is the water located beneath the Earth's surface in soil pore spaces and fractures of rock formations. It's a crucial water supply, accounting for approximately 30% of the world's fresh water.
Aquifers: Natural Reservoirs
Aquifers are underground layers of water-bearing permeable rock or unconsolidated materials from which groundwater can be extracted. They vary in size, and some span thousands of square miles, like the Ogallala Aquifer in the USA.
Recharge Zones: Vital Areas
Recharge zones are areas where surface water infiltrates the ground, replenishing aquifers. They are critically important and vulnerable to pollution, which can contaminate the groundwater for decades or even centuries.
Confined vs. Unconfined
Confined aquifers are trapped between layers of less permeable material, while unconfined aquifers are not. Artesian wells tap into confined aquifers, where water is under pressure and can flow to the surface naturally.
Threats to Groundwater
Groundwater faces threats from over-extraction, contamination, and climate change. Excessive withdrawal can lead to subsidence, where land sinks, as seen in California's Central Valley, and can also reduce water flow to springs and rivers.
Groundwater and Ecosystems
Groundwater is a key part of many ecosystems, supporting wetlands and rivers during dry periods. Remarkably, some fish species have adapted to live in complete darkness within groundwater systems, like the Mexican blind cavefish.
Managing Groundwater Sustainably
Sustainable groundwater management involves balancing use with recharge and preventing contamination. Innovative methods such as managed aquifer recharge, where excess surface water is intentionally infiltrated to aquifers, are being developed to preserve this vital resource.