Why is water spewing forth from the dolomite cliff face? Well dolomite is a form of limestone, and limestone makes up bedrock, along with sandstone and granite to name a few. Remember my Cave post with the underground streams? The water is underground water encased in bedrock. These cliffs are where the cave was located. Now the water is frozen in time.
Bedrock has voids where groundwater accumulates. And the bedrock can become fractured due to winter’s expansion and contraction as an example, creating additional space for water to gather. Within bedrock, other denser materials that prevent downward movement of percolating water, like clay and granite act as a confining layer. This may stop the vertical movement and the water will pool. Then reaching a full capacity, the water then runs horizontal, leading to an opening where it can reach a surface.
Water at very shallow depths might be just a few hours old and at moderate depth, it may be 100 years old by the time it is freed from the aquifer. It is not the age of the bedrock that it is encased in. Aquifers are layers of rock and soil saturated with water.
The image below is surface runoff water.
Surface runoff is the flow that occurs when soil is infiltrated to full capacity and the excess of rain or water melt flows over the land and can not be absorbed.
Here is the difference between surface and ground water according to Purdue University.
Surface water is water found over the land surface in streams, ponds, marshes, lakes or other fresh (not salty) sources. Ground water is water occurring in the zone of saturation in an aquifer or soil. Other than the location, one of the primary differences between surface and ground water is that ground water moves much slower than surface water. This is because ground water experiences far more friction as it moves through the pores in soil then surface water experiences as it flows over the earth’s surface. Surface water is much more easily contaminated than ground water. Filtration through the soil helps clean ground water.
Ground water is the source of about 40 % of the water used for public supply. It provides drinking water for more than 97 % of the rural population who do not have access to public water-supply systems. Even some major cities, such as San Antonio, Texas, rely solely on ground water for all their needs. Between 30 % and 40 % of the water used for agriculture comes from ground water. Withdrawals of ground water are expected to rise in the coming century as the population increases and available sites for surface reservoirs become more limited. Purdue University
The water gets underground from rain, hail and snow. There is one hundred times more water in the ground than is in all the world’s rivers and lakes, source USGS. Ground water makes up the third largest supply of water on Earth, behind the oceans at 97 percent. Glaciers are 68.5 percent of the 3 percent that is freshwater. Of this 3 percent fresh water, 30 percent is groundwater. Here is a chart showing it rather concisely. Click to enlarge.
In 1990, about 339,000 million gallons per day of fresh water was withdrawn from our surface and ground water sources, such as wells, rivers, lakes, and reservoirs. Purdue University
Here’s the breakdown by water-use category from the US Geological Survey:
- Irrigation 40 %
- Thermoelectric power 39 %
- Public Supply 11 %
- Industry 6 %
- Livestock 1 %
- Domestic 1 %
- Mining 1 %
- Commercial 1 %
These are just some interesting facts about water that you may be drinking or polluting. Hopefully no one reading this post is the latter. Just think about water runoff and what you might be contributing.
I know I will this coming year make a concerted effort to think about every drop on my property. I guess you can say it is what I will do better in my garden this year. My garden is very tiny so it is easier to make it better than new and different. And on this note, I am linking this post to fer’s World Garden Carnival.
To get more information pertinent to your own live’s and water usage, go to Elephant’s Eye post, Water, drought in Beaufort West, and floods.