Plains

Plains are landforms with a wide, flat or gently rolling surface. They have no large hills or deep valleys, and are generally not more than 300 metres above sea level. (Sea level, also called mean sea level, is the average level of the surface of the oceans.)

Where does a plain's famous soil come from? Not from the plain. Floodplains are plains formed by rivers that start in the mountains. On the way down, the rivers pick up bits of rock, sand and silt, called sediments. They carry them all the way to the plains, and where the river slows down it drops them, making the soil very fertile.

So these plains are ideal for growing all kinds of crops, and farming is a major occupation there. Plains also support many plants and animals.

Thousands of years ago, the first civilisations grew up around rivers in fertile plains. Today too, a large part of the world's population lives on plains. About 40 crore people, more than one-fourth of India's population, live in India's Ganga plain (often called the Gangetic plain).

The main occupations there are river fishing and farming. Food crops such as rice, wheat, maize, barley and millets are grown, and so are fibre crops such as cotton, jute and hemp.

Traditional farming here was mostly rainfed (watered only by rain). In recent decades farmers have turned to irrigation, bringing water to the fields through canals or pumping it from groundwater. Irrigation has increased production, but it has also helped use up groundwater faster than it is refilled. That is a challenge for the future of farming in the region. The Ganga plain also faces high population and pollution.

Whether in mountains or plains, rivers have always mattered greatly to people's culture. Many communities treat a river's source and its confluence (the meeting point of two or more rivers) as sacred. And because plains slope gently, boats travel easily on their rivers, which supports a lot of trade and work.