Water on the Earth’s surface is categorised into two categories: salty water and fresh water. Fresh water is the water that contains less than 1000 milligrams per litre of dissolved solids (most often salt). Natural glaciers and icebergs, ice sheets and ice caps, bogs, ponds, lakes, rivers and streams, and groundwater in aquifers and underground streams are some of the examples of fresh water. Fresh water is the only form of water which is potable, leaving some exceptions which need proper purification before making it fit for drinking.
The Great Lakes the largest fresh water body, are found between the borders of the US and Canada.
Rivers: Any natural stream of water that flows through a channel is called a river. A river has a defined bank bedded with sand and gravel. The water in a river comes from different sources, such as rain water, melting snow and ice, and from springs and some part from lakes. Rivers carry rain and other forms of the Earth’s surface water to the sea, or to other rivers that enter dry plains and inland lakes. This is a continuous way to regulate the Earth’s water cycle. Large rivers have many tributaries or smaller streams that flow into the main stream.
The Colorado river in Arizona (USA) has cut a massive gorge and created the Grand Canyon.
Tributary: A river or stream that flows into a larger river or lake is called a tributary.
River Basin: A land that is drained by a river and its tributaries is called the river basin. A basin sends all the water collected in it to a central river which is connected to the ocean. Basins are generally divided into two parts: watersheds and areas around a smaller river, lake or stream. Many smaller watersheds make a big river basin. River basins support life and agriculture of a particular region. River basin plains are very fertile as they get deposits of mineral from the adjoining flowing river. For example, the Gangetic River Basin in India is densely populated and dependent on River Ganga, especially for agriculture.
Watershed: It is a land piece that is drained by a river system.
