Water of Life Key Concept b) Fresh, clean water is a relatively scarce resource
Maybe planet Earth should have been called planet Water instead, for it is a watery world. Over two thirds of the surface of the planet is covered by water, around the same percentage of our bodies that is water!
Water exists in many forms in nature – as ice, liquid (freshwater and saltwater) and water vapour. About 97 percent of the water on Earth is ocean. Of the remaining three percent (which is freshwater), over two thirds is locked in icecaps and glaciers. This means that less than one percent of the world’s water is liquid freshwater. Of this one percent, the vast majority is too deep in the ground to extract, or too polluted to drink. So, only a tiny percentage (0.0003%) of the total water on the planet is available to drink.
Globally, clean drinkable water is a very limited resource. In New Zealand, we are fortunate to have relatively abundant freshwater due to our high rainfall. However, we can tell a lot about our relationship with the environment by the condition of our local water resources, and in some places pollution is a serious problem. Parts of the country also experience drought and sometimes summer water restrictions are in place. Some of our groundwater aquifers are also being over-extracted, for domestic supply or irrigation. Over-extraction of groundwater can result in lower flows in streams fed by groundwater, or in coastal areas, salty water may flow into the aquifer, making it less suitable to drink.
When we take too much water from our streams or aquifers, our rivers and streams may not have enough flow to support the aquatic life forms that depend on that water. So we have to think seriously about how much water we can take, what it is used for, and how to minimise our water use. Figuring out the fairest way to share water between people and aquatic ecosystems is an important part of our community decision-making. We also need to consider how our groundwater aquifers can get recharged from water draining through the land above, without it becoming polluted along the way.