Introduction to the Topic

In the study of geography, the term 'drainage' refers to the river system of an area. If you look at a physical map of India, you will notice that small streams flowing from different directions come together to form a main river, which eventually drains into a large water body, such as a lake, a sea, or an ocean. The area drained by a single river system is called a drainage basin. Any elevated area, such as a mountain or an upland, that separates two drainage basins is known as a water divide.

Understanding drainage is crucial because rivers are the lifeblood of our civilization. They provide water for drinking, agriculture, and industry, and they have shaped the history and culture of India. In this chapter, we explore the diverse river systems of India, categorized primarily into the Himalayan rivers and the Peninsular rivers.

Key Concepts Explained

1. The Two Major Groups of Indian Rivers

The Indian rivers are divided into two major groups based on their source and characteristics:

  • Himalayan Rivers: These rivers originate from the Himalayan mountains. They are perennial, meaning they have water throughout the year because they receive water from rain as well as from melted snow from the lofty mountains. The major Himalayan rivers are the Indus, the Ganga, and the Brahmaputra.
  • Peninsular Rivers: Most of the Peninsular rivers are seasonal, as their flow is dependent on rainfall. During the dry season, even the large rivers have reduced flow of water in their channels. They have shorter and shallower courses compared to their Himalayan counterparts.

2. The Himalayan River Systems

The Himalayan rivers have long courses from their source to the sea. They perform intensive erosional activity in their upper courses and carry huge loads of silt and sand. In the middle and lower courses, these rivers form meanders, oxbow lakes, and many other depositional features in their floodplains. They also have well-developed deltas.

The Indus River System

The river Indus rises in Tibet, near Lake Mansarowar. Flowing west, it enters India in the Ladakh district of Jammu and Kashmir. It forms a picturesque gorge in this part. Several tributaries, such as the Zanskar, the Nubra, the Shyok, and the Hunza, join it in the Kashmir region. The Indus flows through Baltistan and Gilgit and emerges from the mountains at Attock. The Satluj, the Beas, the Ravi, the Chenab, and the Jhelum join together to enter the Indus near Mithankot in Pakistan. With a total length of 2,900 km, the Indus is one of the longest rivers of the world.

The Ganga River System

The headwaters of the Ganga, called the 'Bhagirathi', is fed by the Gangotri Glacier and joined by the Alaknanda at Devprayag in Uttarakhand. At Haridwar, the Ganga emerges from the mountains onto the plains. The Ganga is joined by many tributaries from the Himalayas, some of them being major rivers, such as the Yamuna, the Ghaghara, the Gandak, and the Kosi. The river Yamuna rises from the Yamunotri Glacier and flows parallel to the Ganga. The Ganga flows eastwards up to Farakka in West Bengal, which is the northernmost point of the Ganga delta. The river bifurcates here; the Bhagirathi-Hooghly flows southwards through the deltaic plains to the Bay of Bengal, while the main stream flows southwards into Bangladesh and is joined by the Brahmaputra.

The Brahmaputra River System

The Brahmaputra rises in Tibet east of Mansarowar lake, very close to the sources of the Indus and the Satluj. It is slightly longer than the Indus, and most of its course lies outside India. In Tibet, the river carries a smaller volume of water and less silt as it is a cold and dry area. In India, it passes through a region of high rainfall. Here the river carries a large volume of water and considerable amount of silt. The Brahmaputra has a braided channel in its entire length in Assam and forms many riverine islands. Every year during the rainy season, the river overflows its banks, causing widespread devastation due to floods in Assam and Bangladesh.

3. The Peninsular River Systems

The main water divide in Peninsular India is formed by the Western Ghats. Most of the major rivers of the Peninsula, such as the Mahanadi, the Godavari, the Krishna, and the Kaveri, flow eastwards and drain into the Bay of Bengal. These rivers make deltas at their mouths. The Narmada and the Tapi are the only long rivers which flow west and make estuaries.

The Narmada Basin

The Narmada rises in the Amarkantak hills in Madhya Pradesh. It flows towards the west in a rift valley formed due to faulting. On its way to the sea, the Narmada creates many picturesque locations, like the 'Marble Rocks' near Jabalpur and the 'Dhuadhar Falls'.

The Tapi Basin

The Tapi rises in the Satpura ranges, in the Betul district of Madhya Pradesh. It also flows in a rift valley parallel to the Narmada but it is much shorter in length. Its basin covers parts of Madhya Pradesh, Gujarat, and Maharashtra.

The Godavari Basin

The Godavari is the largest Peninsular river. It rises from the slopes of the Western Ghats in the Nasik district of Maharashtra. Its length is about 1,500 km. Because of its length and the area it covers, it is also known as the 'Dakshin Ganga'.

4. Lakes and Their Importance

India has many lakes. These differ from each other in size and other characteristics. Most lakes are permanent; some contain water only during the rainy season. A lake helps to regulate the flow of a river. During heavy rainfall, it prevents flooding and during the dry season, it helps to maintain an even flow of water. Lakes can also be used for developing hydel power, enhancing natural beauty, and providing sites for recreation and tourism.

5. Role of Rivers in the Economy

Rivers have been of fundamental importance throughout human history. Water from rivers is a basic natural resource, essential for various human activities. Therefore, riverbanks have attracted settlers from ancient times. Using rivers for irrigation, navigation, and hydropower generation is of special significance, particularly to a country like India, where agriculture is the major source of livelihood of the majority of its population.

6. River Pollution

The growing domestic, municipal, industrial, and agricultural demand for water from rivers naturally affects the quality of water. As a result, more and more water is being drained out of the rivers reducing their volume. On the other hand, a heavy load of untreated sewage and industrial effluents are emptied into the rivers. This affects not only the quality of water but also the self-cleansing capacity of the river. Concerned over rising pollution in our rivers, the Government of India launched various action plans, such as the Ganga Action Plan (GAP).

Summary & Key Takeaways

  • Drainage Basin: The area drained by a single river system.
  • Water Divide: An upland or mountain separating two drainage basins.
  • Himalayan Rivers: Perennial, long courses, intensive erosion, form deltas (Indus, Ganga, Brahmaputra).
  • Peninsular Rivers: Seasonal, shorter courses, flow mostly towards the East (except Narmada and Tapi).
  • Dakshin Ganga: Another name for the Godavari river due to its size and significance.
  • Economic Value: Rivers are vital for irrigation, electricity, and transport.
  • Conservation: Increasing pollution requires active government intervention and public awareness to save our river systems.