Water is a very important part of our environment. It is found covering nearly three quarters of the Earth’s surface. It is fun to splash in and it is also needed for life. In fact, we can survive much longer without food than without water to drink. Every living thing needs water. Without it, plants and trees will not grow; fish, clams, dolphins and other aquatic life will have nowhere to live; and animals like otters who find their food in the water will have nothing to eat.

Have you ever heard someone refer to water as H2O? Why do you suppose someone might call water by this name? Water is a basic molecule made up of two hydrogen atoms, and one oxygen atom. When these three atoms come together, they form a strong bond that is difficult to break. The strength of this bond keeps a water molecule together for millions and even billons of years.

Water is one of the most common substances on the Earth. Covering over 70 per cent of the surface of the Earth, it is easy to find. Even in a desert, it is not hard to find water, if you know where to look.

The three forms of water are solid, liquid and gas. Solid water is frozen and known as ice. When water is boiled, or the sun heats the surface of a body of water, its molecules can absorb enough energy to evaporate into the air – that is, to become a gas called water vapor. Up in Earth’s atmosphere, water vapor cools and collects into clouds. When enough clusters of cloud particles stick together, they tumble back down to Earth as rain, snow or hail. This process of water evaporating, condensing and falling to Earth is the water cycle. Water on the Earth can flow above the ground in a stream or river. It can run underground, too. And water can also be frozen into large glaciers. Whichever form it is in, it can be a powerful force, changing the shape of the land as it erodes mountains and carves valleys. Floods are considered very powerful and can easily change the shape of a country.

Floods

The word “monsoon” has been in the news for the past weeks, ever since Monsoon rains triggered what some news outlets are referring to as “the flood of the century” in Pakistan. An estimated 14 million people have been affected by this disaster and as the

figures continue to rise, UNICEF says that six million children have been affected by the floods.

What happens when there is a flood?

A flood is an overflow of an expanse of water that submerges land. Take a bowl of water and put a sponge in it. Keep on adding water to the bowl. You observe that for some time, the sponge absorbs the water but after a while, when it is full, the bowl gets filled more and more until it overflows. This is what happens in a flood. The ground is like a giant sponge that soaks the rainwater until it is full. Some of the water which has not been soaked by the rainwater gets evaporated. The rest is known as runoff and can cause floods.

Lakes

Lakes contain about 90 per cent of all the surface water found on Earth (not including oceans). Lakes form when water finds its way into a basin. In order to continue existing, lakes must have a continual source of new water; otherwise they will eventually dry up.

Most lakes contain fresh water. However, in some cases, the water found in a lake can become salty, just like the ocean. This happens when a lake does not have a stream, either above ground, or underground draining water away from it. As water enters a lake, it carries minerals with it. As this water dissolves, it leaves the minerals behind.

Most lakes only last a few thousand years, and then disappear. This is because as streams and rivers carry water into the lake, they also carry sediment. This sediment slowly fills the lakes, causing them to become shallower. At the same time outbound streams cut deeper and deeper channels, causing the lakes to drain more quickly.

Many lakes are man-made. These are referred to as reservoirs. Reservoirs allow cities and nations to store water for later use. Most of these reservoirs are small in size, but some are very larger, spanning several hundred miles.

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