Evaporation is the transformation that occurs when water from the earth’s soil, plants, and water bodies turns into water vapor. Most of this vapor comes from the world’s oceans; it travels high into the atmosphere where condensation occurs, and clouds are formed. From this vapor state, the clouds condense increasingly until they become water droplets. Eventually, through further condensation, these droplets grow too heavy and the water falls to the Earth mainly as rain and snow.
This precipitation falls to the Earth below – some of the water will flow along the surface. This is known as runoff. The remainder of the water is absorbed into the ground, and is known as recharge. This absorbed moisture travels deep down into the soil, and this moving water is known as groundwater. The groundwater eventually finds it way into aquifers, which are water-bearing, porous rocks or materials, such as silt, gravel, sand.
But the water cycle doesn’t stop there. The groundwater moves through the gaps and spaces between rock and soil, travelling deeper to lower levels underground, and this flow is known as groundwater flow. Years of deep groundwater flow lead eventually to a discharge area, in a natural body of water, becoming surface water. From there, evaporation will naturally occur and the hydrological cycle will start again. Water is perpetually moving, and the cycle has been going for millions of years.
It is estimated that the sum total of all groundwater on earth is 22.6 million cubic kilometres — enough to cover all the land on Earth to a depth of 180 meters (~ 591 feet). However, just 6% of this groundwater is refilled within a human’s lifetime, being about 50 years. This renewable groundwater amounts to only around 0.35 million cubic metres, or basically enough to cover the land on the earth’s surface to a depth of 3 meters (~10 feet).
It can be said that the water billions of people rely on in their daily existence is a non-renewable resource, because the rate of usage of this water is greater than the rate at which it is being replenished. Furthermore, this groundwater tends to be within a few hundred metres of the surface, and high temperatures in arid regions deplete the water, leading to less rainfall. There is also a higher likelihood of being contaminated by pollutants from residential, commercial and industrial sources. Materials such as chemicals, gasoline, and road salts can enter the groundwater and cause contamination, becoming dangerous and unfit for human use.
Ingesting contaminated groundwater can cause health problems. Dysentery, for example, can be the result of drinking water contaminated by septic tank waste. Poisoning can also occur with well water that toxins have leached into. Cancer, too, has been shown to result from prolonged exposure to contaminated water.
What Can We Do To Help Prevent Groundwater Contamination?
• Cut Back & Manage the usage of Chemicals in your Home: Try to use fewer chemicals in your daily life. When you do use toxins - like pharmaceuticals, paint, motor oil, and other substances - know where to safely and properly dispose of these items, such as at the hazardous waste site of the local landfill.
• Green Alternatives: Use natural and nontoxic household cleaners, such as lemon juice, baking soda, and vinegar. They are effective cleaning products, which are also relatively inexpensive, and environmentally-friendly.
• The 3-R’s: Reduce the amount of things you use in your home, and reuse whenever possible. Don’t forget recycling paper, plastic, cardboard, glass, aluminum and other materials.
Learn and be Active! Learn more about groundwater and pass on this knowledge to everyone you can!
BY: ROBERT INGLIS
Contributing from Guelph, ON, Canada