World Water Day, March 22, 2015: Water and Sustainable Development

       
        Think for a minute about water.
Open your kitchen tap and out it comes, letting you cook or wash. After a hot day at work or school, your shower feels so good! Throughout your day, water carries away your waste without you thinking much about it.
But water does a whole lot more.
Water makes energy. According to the U.N., over 80% of power generation comes from thermal electricity: water turned into steam that drives generators. Another 16% of energy comes from hydroelectric dams.
Water grows our food. In many parts of the world, we need to irrigate with water to grow crops, and livestock needs water to drink.
Water helps make products, lots of water. Ten liters of water are needed to make one sheet of paper! This means manufacturing jobs depend on water supply.

The kids in First Year of ESO have been learning about the water cycle. Every molecule of H2O is recycled and reused over and over again. Imagine: You are outside the Instituto and a raindrop falls on your face. Then it falls on the ground. It runs off along the pavement before being caught in a drain. The drain takes it to the Tinto, which takes it to the Atlantic.

The water cycle at work over Gran
Canaria: evaporation of blue,
sunlit water; condensation as
cloud; precipitation as rain
squalls falling on the land.

Under a hot sun, the water molecule in the Atlantic heats and evaporates, and turns into water vapor. Then it rises into the sky. When it hits cooler air, it condenses and becomes part of fog or a cloud. This same cycle is repeated with various players (you drink water, you urinate or sweat, the water goes into the drainage system, and so on... or a tree takes ground water into its roots, then its leaves transpire water which turns to water vapor and rises, and so on...), with our little H2O molecule transforming over and over again.
BUT. Although the water cycle tries very hard to keep clean water moving so it can do all the thousands of jobs it has to do, people often get in the way. Mines and industry pollute ground water and rivers; this can lead to poisoning fish, shellfish, and people. Over-heated water discharged into water bodies can harm both plants and animals that depend on that water body.
Overuse of water means that the water cycle is distorted: some places get far too much water; other places get none at all. Both situations can lead to economic hardship, disease, and conflict.
We have to conserve our water and protect its quality. That's what "sustainable" means. There's enough water for everyone--if we use it properly. That means keeping it clean and using it wisely, without wasting it.
So let's celebrate water and its sustainable use on March 22! You can learn more at: http://www.unwater.org/worldwaterday/home/en/