Sustainability of Our Groundwater Aquifers
Alan L. Johnson
Growing up around the great lakes in Ohio, we didn't ever worry about water. It was something we enjoyed during the summer while at the beach and or cruised our boats on to fish. To this day, Ohioans are blessed with the largest body of fresh water in the world; the Great Lakes. However, this is not the case throughout most of the world. From arid or dry places where it seldom rains,to coastal towns where the water is not potable due to its saline content, most of the world deals with serious water issues.
Aquifers and Groundwater
A huge amount of water exists in the ground below your feet, and people all over the world make great use of it. But it is only found in usable quantities in certain places underground — aquifers. Read on to understand the concepts of aquifers and how water exists in the ground.
In fact, about 20% of the world’s fresh water supply comes from groundwater. Rain and snow is collected underground in a “rock pocket” called an aquifer. Soil pore spaces in the ground become saturated with water, and this maximum depth is called the water table.
An aquifer is an underground layer of water-bearing rock. Water-bearing rocks are permeable, meaning that they have openings that liquids and gases can pass through.
Recently, Earth and Space Science News published a piece on work that is being done to monitor some of the world's most influential aquifers.
"The largest aquifers in the world are a vital source of freshwater for agriculture and other human uses. During times of drought, these resources are crucial to food security; understanding groundwater storage and depletion is vital, especially as climate change worsens drought conditions."
What is amazing is that a group of individuals is trying to create a sustainability index to help disclose which water sources are at the most risk.
"To tackle this problem, Thomas et al. paired GRACE data with specific sustainability indicators to analyze the world’s largest aquifers. They incorporated groundwater storage data from their GRACE Groundwater Drought Index (GGDI) tool and focused on three primary performance indicators: reliability, resilience, and vulnerability. These indicators, typically used in water resources systems, characterize the likelihood of the aquifer’s ability to be used dependably in the future."
The results of the research were telling although not all that surprising when one looks at where the highly vulnerable low resilient areas are located.
"Aquifers in arid regions like the Sahara, the Arabian Peninsula, and California’s Central Valley exhibited high vulnerability and low resilience. These aquifers are overstressed and nonrenewable; however, their large storage capacity can make up for slow recharge time, so they also ranked as more reliable."
However when the researchers looked at higher resilient aquifers they noticed:
"In contrast, aquifers in northern latitudes and regions with high precipitation had low reliability scores but high resilience scores due to faster recharge."
And in fact the least vulnerable aquifers became the ones in lush regions:
"Because vulnerability is largely influenced by groundwater recharge, the least vulnerable aquifers were found in lush regions like equatorial Africa and northern Europe and Asia."
Lastly, the researchers calculated a sustainability index to track changes across all three performance indicators. What is novel about this approach is that it blended a few methods together which will now allow for quantifying and monitoring aquifer sustainability through time and continued use.
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Sustainability of our natural water sources and the aquifers that hold 20% of them are imperative to our civilization. Without potable water, life as we know it ceases to exist. Seeing modern machine learning methods being used to analyze aquifer data sets and align it to a predictive sustainability index is really promising. Let's hope we can use this as another data point to now tackle the larger issue of global warming.
Reality Changing Observations:
Q1. Do you live in a part of the world where water is scarce or plentiful and how has that shaped your relationship with water?
Q2. Do you know where your fresh water comes from and how it got there?
Q3. What can you do personally to raise awareness about aquifer depletion tied to global warming?