By Ashraf Naushahi

In nature, there is no scarcity of water. There is a natural water cycle keeping water

continuously on the move. Because of the water cycle there cannot be a scarcity of

water in total on the Earth. Let's see how.

Oceans are largest collections of water on the Earth. Rivers, lakes, streams, and many

other large collections of water are also there on the Earth. Now, when sun light falls on

any surface of water, its water is evaporated into the atmosphere. In atmosphere, water

is cooled making tiny water droplets and these tiny water droplets form clouds. Clouds

are full of cool water. A change in temperature results in melting of cool water and there

is rainfall or snow in areas above which clouds are floating at the time of melting.

Thus total quantity of water in the world remains the same.  

An understanding of the water cycle remains incomplete without some understanding of

how snow, glaciers, rivers and other water resources function within the water cycle. 

When flakes of frozen water fall from clouds to the surface in cool regions of the Earth,

snow is formed. Its flakes are small crystals. When a large mass of ice is accumulated,

it is called a glacier. It is made of a large mass of recrystallized ice. Because of its heavy

weight, it starts moving very slowly while changing its directions. That's why it is sometimes called a river of ice too. When speed of a glacier becomes equal to the rate of its ice melting, the glacier stops moving forward.

    

There are three main types of glaciers: mountain or valley glaciers, piedmont glaciers,

and ice-sheet or ice-cap glaciers. Valley or mountain glaciers are formed in valleys or

mountainous areas. Piedmont glaciers develop when valley glaciers spread out in plain

areas. Ice-sheet glaciers are formed in polar areas. Glaciers that cover large areas in

polar regions are called ice-sheets. Icy regions of Greenland and Antarctica are,

therefore, ice-sheets or big glaciers.

Rivers are large water resources containing water for most of the human needs as

drinking, cooking, washing, growing grains, vegetables, fruits and other crops.

Oceans and seas contain more water but sea water is not good for human needs.

Though, in some parts of the present day world, sea water is made useful for human

needs through scientific methods, usually it is river water only that people can drink

and which is useful for agricultural or industrial purposes.  

Rivers contain large quantities of water and flow from higher to lower areas. Many

small resources of water are also parts of a river, therefore, a river is sometimes

called not only a river but a river system. In other words a river system is a network of

connected water resources having water, sand, mud and sediments. With the flow of

river water, sediments, rocks, sand and minerals dissolved in it, are transported from

place to place. After covering a large distance, rivers go to the sea.

Different rivers have different beginnings. Some rivers start from melting glaciers.

Rainfalls or natural water-springs are the beginnings of some other rivers. Whatever

be beginning of a river, its water-flow is fastest in the beginning. Its speed decreases

as it goes away from its start. It is because more and more mud is dissolved into its

water as it moves forward. With its flow, river water takes rocks, sand and sediments

with it. River water spreads on a wide area when it reaches near the sea.

Published in Young Nation Magazine on June 17, 2017