Key Characteristics of Groundwater
- Groundwater is freshwater that flows underground or is stored in underground pools and reservoirs.
- Groundwater flows continuously, but very slowly, through the soil or through connected networks of sheets of water, veins and pools.
- Groundwater is refilled by rainfall. When rainfall drains down through the pores in soil, it meets a tough layer of soil – usually clay or rock – through which it cannot travel.
- Groundwater collected in areas of sand and gravel beneath the surface, or through breaks in the bedrock. Limestone has many pores that can hold water.
- Occasionally groundwater surfaces in lakes and streams or is absorbed by plants.
- Groundwater is the primary source of fresh drinking water for humans. As such it is more important than precious metals. Increasingly water will be treated as gold – monitored, metered and priced.
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Environmental Challenges
Groundwater is the primary source of fresh drinking water for humans. Unfortunately, groundwater can be contaminated in many ways, such as road salt, animal wastes, leakage from underground tanks, and oil poured on the ground. Moreover, it takes a very long time to flush out or remove pollutants in sand and gravel aquifers, and it is almost impossible to repair polluted bedrock groundwater.
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A Visit to Groundwater in Hawaii
Hello fellow Global Lab investigators:
We would like to share with you our visit to one of our local watersheds. The watershed is located in the Ko-olau Mountains (on the island of Oahu where we live). The Ko'olau range receives about 300 inches of rain a year.
[Question: How many fewer or more inches of rain do you receive every year?]
To visit the water, the bus had to park on the road, and we walked-hiked up the mountain trail in a rainforestfor about 2 miles before we came to a small clearing. It had been raining hard the night before so the trail was both muddy and slippery. But we were warned and used our old shoes for the purpose. Once we got to the clearing we put our gear down under a makeshift tent and looked at the beauty of our surroundings.
We came with our flashlights, and water was running out of the tunnel. We caught some of the water in paper cups and tasted it: it was cool, clear and sweet! We learned that it takes 25 years for water to go from rain falling on the mountain to water flowing into our homes. The water was older than we were!
Our water source is underground. The rain soaks into the porous lava rock that makes up our island and gets purified in the process…We are lucky to have such a clean supply of water, and we will do what we can to protect our watersheds…
Global Lab students in Honolulu, Hawaii, Teacher, Consuelo Rogers |
B. Feldman