Groundwater Geology
(Hydrogeology)
Dr. J Bret Bennington
Department of Geology
Hydrosphere
Liquid water in oceans and above and below surface of continents.
Ice in polar regions and at high elevations.
Water Vapor in the atmosphere.
1.3 Billion cubic kilometers of water on Earth
97.5% is saltwater
2.5% is freshwater
Storage
Storage
Storage
Storage

Questions for Discussion
What is the largest reservoir of water?
What is the largest reservoir of freshwater?
What is the largest reservoir of accessible freshwater?
Questions for Discussion
Why are the oceans salty?
If rain comes from the oceans, why is it freshwater?
What happens to the water that falls on the continents as precipitation?
Why do streams and rivers continue to flow even if it hasn’t rained for weeks?

Groundwater is humanity’s most important geological resource
International Association of Hydrologists,
“Today a global withdrawal of 600-700 km 3 /yr makes groundwater the world's most extracted raw material.”
UN http://www.irinnews.org/webspecials/runningdry/default.asp
Groundwater is much more important than surface water as a resource
“For example, the Amazon River carries about 15 percent of the Earth’s freshwater runoff but supplies water to less than 1 percent of the world’s population.”
UN http://www.irinnews.org/webspecials/runningdry/default.asp
Groundwater is a critical resource for development
“[groundwater] extraction has been and remains a cornerstone of the Asian 'green agricultural revolution,' it also provides about
70 percent of piped water supply in the
European Union and effectively supports rural communities across large areas of sub-
Saharan Africa.”
UN http://www.irinnews.org/webspecials/runningdry/default.asp

Groundwater cuts across all aspects of economies
To produce 1kg of coffee, a staggering
20,000 litres of water are needed. The virtual water content of a single, 250g hamburger is 11,000 litres, while 1kg of cheese and sugar require 5,000 and 3,000 litres respectively. Even 1kg of milk sucks up
2,000 litres of water, while a normal cotton
T-shirt hijacks as much as 7,000 litres.”
UN http://www.irinnews.org/webspecials/runningdry/default.asp
Groundwater is a endangered resource in much of the world
“According to some estimates, the amount of water being used globally is more than twice the quantity being recharged by rainfall every year.
India, China and Pakistan alone account for more than half the world’s total use of underground water for agriculture. Clearly, the level of current usage is unsustainable. “The farmers are certainly destroying their children’s future, if not their own,”
UN http://www.irinnews.org/webspecials/runningdry/default.asp

What do hydrologists do?
Surface water engineering / management
Groundwater impact on Earth materials properties (slope stability, subsurface construction)
Water chemistry
Groundwater supply and wells
Aquifer protection and remediation
Environmental and groundwater law