How water reserves in aquifers are measured

Water is an essential and increasingly scarce resource, so understanding and managing groundwater reserves in aquifers is essential to guarantee water supply. But how exactly is the water stored underground measured?

An aquifer is a geological formation that can store and transmit groundwater. These systems are composed of materials such as sand, gravel or porous rock, and their storage capacity depends on factors such as porosity and permeability. Aquifers are a crucial source of fresh water, especially in arid regions or with limited access to surface water bodies.

Methods for measuring water reserves in aquifers

Measuring water reserves in aquifers involves the use of direct and indirect methods. Next, we describe the main techniques used by scientists:

1. Piezometric measurements

Piezometers are devices installed in wells that measure the height of the water table, that is, the surface of the groundwater. These data help determine changes in aquifer storage and recharge.

2. Pumping tests

Water is drawn from a well at a constant rate while the drop in water level is measured. This allows the transmissivity and storage of the aquifer to be calculated, properties that indicate its ability to store and transmit water.

3. Remote sensors

Satellites equipped with technology such as GRACE (Gravity Recovery and Climate Experiment) measure small variations in the Earth’s gravitational field, which reflect changes in groundwater reserves. This method is especially useful for large-scale monitoring.

4. Geophysical methods

Techniques such as electrical and seismic resistivity allow mapping geological formations and estimating the amount of water contained in them. These tools are non-invasive and highly effective.

5. Mathematical modeling

The computer models integrate geological, climatic and land use data to simulate the behavior of the aquifer and estimate its storage and recharge capacity.

(Photo: Wikimedia Commons)

Importance of measuring aquifer reserves

Accurate assessment of groundwater reserves is essential to:

-Sustainable management: Avoid overexploitation and guarantee long-term supply.

-Adaptation to climate change: Plan for events such as prolonged droughts.

-Protection of the ecosystem: Maintain the ecological balance that depends on groundwater.

The measurement of aquifer reserves faces obstacles such as the lack of historical data, geological heterogeneity and the high costs of certain techniques. However, advances in remote sensing, artificial intelligence and big data analytics are revolutionizing this field, improving accuracy and reducing costs.