Going Underground: How We Study Aquifers

Apr 27, 2023
 by Seven Seas News Team

Permeable formations in aquifers may be composed of gravel, sandstone, conglomerates, or limestone, and aquifers are frequently categorized by the type of rock or sediment that constitutes them.

We can’t see them, but we can still determine the characteristics of these formations

An aquifer is a permeable geological formation that is saturated with groundwater. Because aquifers supply half of the world’s drinking water and more than a third of irrigation water, it’s vital to study them. We need to know the quality and quantity of water, how to plan water use and managed aquifer recharge programs, and more. We need to understand their properties.

Some Properties of Aquifers

Aquifers are generally classified as confined or unconfined. Confined aquifers lie below a layer of impenetrable rock or clay, and unconfined ones lie below permeable soil.

An aquifer’s porosity refers to the percentage of open space between grains of sediment. It’s a measure of storativity, or storage capacity.

Permeability is one of the most important properties of aquifers. It’s the measure of how efficiently water flows from one pore or space to the next. Larger pores equal less friction. Smaller pores mean more friction and more twists and turns. Permeable formations in aquifers may be comprised of gravel, sandstone, conglomerates, or limestone, and aquifers are frequently categorized by the type of rock or sediment that constitutes them.

It’s also important to determine whether aquifers have been contaminated with salt, industrial pollution, or pesticides, and whether they are being depleted.

A Few Techniques for Studying Aquifers

To determine all these properties in an aquifer, tests can be done by pumping water from a well and measuring the water level response in nearby wells. The process takes days, but there is a quicker pumping test that takes only minutes. Slug tests involve making a quick increase or decrease in well level and monitoring the effects for a quick estimate.

Groundwater modeling builds a computer model of an aquifer based on geological data, water levels, pumping tests, and more. We can’t see underground, but an accurate model of a groundwater system can simulate different hydrologic scenarios, providing an alternative to field observation for analysis.

Other Techniques for Observation

Aquifers can also be characterized by geophysical techniques such as electrical resistivity, electromagnetic induction, ground-penetrating radar, and seismic tests. Water chemistry analyses and isotope analyses can determine groundwater sources, age, and contamination levels. Another technique introduces a tracer into groundwater and tracks it to determine the direction and speed of water flow.

Remote sensing techniques use satellite imagery and more to study surface and subsurface features that can affect groundwater recharge and discharge. Groundwater level monitoring can identify changes in groundwater storage and recharge.

Applying Our Aquifer Knowledge

Once all this knowledge is in hand, groundwater can be properly protected and improved.

Where aquifers contain too much salt, desalination can make the water usable. Where groundwater contains pollution from industry or from agriculture, it can be treated to remove the contaminants.

Where aquifers are depleted, recharge programs that divert stormwater or treated wastewater into them can slow, stop, or reverse depletion. Conservation, efficiency, and wastewater reuse can reduce the amount of water that must be extracted from aquifers.

For more about how to make the most of groundwater, including through desalination and water reuse, contact Seven Seas Water Group. Water infrastructure can be costly, but our Water-as-a-Service® can bring water reuse and desalination to more people than possible before.

Image Credit: cc0collection/123RF