Drainage (Class 9 Geography Chapter 3 Notes)

Major Rivers and Dams of India/Source: NROER

Drainage

1. Drainage can be defined as the system of rivers and stream of a region.
2. The area drained by a river system is known as the drainage basin.
3. A river along with its tributaries is known as a river system.
4. Any elevated area such as mountains which separates two drainage basins is known as a water divide.

Drainage Pattern

1. On the basis of slope, rock structure and climatic conditions of area, small streams and rivulets within drainage basin form a pattern. This pattern is known as drainage pattern.
2. There are four major drainage pattern that can be formed. These are dendritic, trellis, rectangular, and radial patterns.
3. Didentric Pattern forms when streams follows slope of terrain.
4. Trellis Pattern forms when streams joins the main river at almost right anles. It appears where hard and soft rock exists in parallel to each other.
5. Rectunglar Pattern forms where there are strongly jointed rocky terrains.
6. Radial Pattern forms when streams flow from different direction from a central peak or dome like structure.
7. In a drainage basin, a combination of patterns can be observed.

Drainage System of India
The drainage system of India is mainly controlled by its physical features. According to its features, the rivers of India can be divided into: 1. The Himalayan Rivers and 2. The Peninsular Rivers.

The Himalayan Rivers

1. The Himalayan rivers are perennial in nature means that they can flow throughout year.
2. These rivers receive their waters from ice caps of Himalayas as well as rain.
3. The three major Himalayan rivers: Indus, Ganga and Brahmaputra.
4. They are known for river features such as meanders, ox bow lakes and delta.
5. They have longer route than the Peninsular rivers.
6. The Northern plains of India is result of the works of these three rivers and their tributaries.

The Indus River System

1. The Indus river rises near Lake Mansarover in Tibet, China.
2. It enters India via Ladakh region.
3. Its several tributaries Zaskar, Nubra, Shyok and Hunza joins it in the Kashmir Valley. It then flows through Gilgit-Baltistan and emerges from Attock mountain.
4. Satluj, Beas, Ravi, Chenab and Jhelum joins the Indus near Mithankot in Punjab region of Pakistan. From there, it flows northward to meet the Arabian Sea near Karachi port.
5. It's total length is around 2900 km and it flows through the Indian states of Jammu and Kashmir, Himachal Pradesh, Punjab and Pakistani states of Punjab and Sindh.

Indus Water Treaty (1960)
According to the Indus Water Treaty between India and Pakistan, India can use 20 per cent of total water carried by Indus river system. India mostly uses this water for irrigation purpose in Punjab, Haryana and Rajasthan.

The Ganga River System

1. The headwaters of Ganga, the Bhaghirathi river, is fed by the Gangotri Glacier.
2. It is joined by Alaknanda river at Devprayag to form Ganga.
3. Ganga is later joined by its other tributaries such as Yamuna, Ghaghara, Gandak and Kosi in its course.
4. Yamuna rises from Yamunotri glacier and flows parallel to Ganga and meets Ganga at Allahabad.
5. Ghaghara, Gandak and Kosi rises from the Nepal Himalayas and are known for their flloding activities in Northern plains.
6. Chambal, Betwa and Son are other three major tributaries of the Ganga. These rivers rises from the Peninsular region of India.
7. Chambal and Betwa are in fact tributaries of Yamuna. which is tributary of Ganga. Chambal meets Yamuna at Jalaun District of Uttar Pradesh. Betwa meets Yamuna at Hamirpur (Orchha District) Uttar Pradesh. The Son river meets Ganga at Patna, Bihar.
8. Ganga flows eastward till Farakha in West Bengal and bifurcates from here into Bhagirathi-Hooghly.
9. The mainstream flows further southward and enters Bangladesh.
10. It is joined by Brahmaputra to form the world's largest delta, Sunderbans before emptying into the Bay of Bengal.
11. In Bangladesh, it is locally known as Meghna.

Ambala

1. Ambala acts as the water divide between the Indus and the Ganga river system.
2. The region between Ambala and Sunderbans is 1800 km wide and have only 300 m fall in its slope. Therefore, one can see large meanders made by Ganga in this region.

Brahmaputra River System

1. Brahmaputra rises from east of Mansarovar lake in Tibet as Tsang Po river.
2. It is slightly longer than Indus river and most of its course lies outside India.
3. It flows eastward in Himalayas and on reaching Namcha Barwa, it takes right turn and enters India through Arunachal Pradesh.
4. It is known as Dihang locally in Arunachal Pradesh and joined by the Dibang and Lohit in due course.
5. It moves further southward , crosses Dhubri, Assam and enter Bangladesh. In Bangladesh, it is known as Jamuna river.
6. Brahmaputra is known for riverine islands in the Northeast region. Majuli, the world biggest riverin island is on Brahmaputra river.

The Peninsular River

1. A large number of Peninsular rivers are seasonal rivers means they are heavily dependent on monsoon for their waters.
2. Even waters in large rivers is reduced during dry season.
3. They have shorter and shallower course than the Himalayan rivers.
4. These rivers can be subdivided into east flowing rivers which empties into the Bay of Bengal and west flowing river which empties into the Arabian Sea.

East flowing river

1. These rivers emerge from the Western Ghats and flow into the Bay of Bengal.
2. These rivers are known for their deltas, which are very fertile in nature.
3. The major east flowing rivers are Mahanadi, Godavari, Krishna and Kaveri.
4. Other minor east flowing rivers are Damoder, the Brahmani, the Baitarni and the Subarnrekha.

West flowing river

1. These rivers flows westward and empties into the Arabian Sea.
2. These rivers make estuaries which have brakish soil and not fit for agricultural activity.
3. The major westward flowing rivers are Narmada and Tapi.
4. Other minor westward flowing rivers are Sabarmati, Mahi, Bharathpuzha and Periyar.

The Narmada Basin

1. The Narmada river rises near Amarkantak Hills in Madhya Pradesh.
2. It flows in a rift valley formed due to the faulting.
3. Some of the works of Narmada are Jabalpur Marble Rocks and Dhuadhar falls.
4. It covers part of Madhya Pradesh and Gujarat.

The Tapi Basin

1. The Tapi river rises from Satpura Hills in Madhya Pradesh.
2. It flows in a rift valley in parallel to the Narmada.
3. It covers part of Madhya Pradesh, Gujarat and Maharashtra.

The Godavari Basin

1. The Godavari river is the largest river of the Peninsular India.
2. It rises from slopes of the Western Ghats near Nasik (Maharashtra) and empties into the Bay of Bengal.
3. It is 1500 km long and its basin covers the part of Maharashtra, Madhya Pradesh, Odisha and Andhra Pradesh.
4. Purna, Wardha, Pranhita, Manjra, Wainganga and Penganga are the major tributaries of the Godavari river.
5. Due to its size and cultural importance, it is known as the Dakshin Ganga.

The Mahanadi Basin

1. The Mahanadi river rises from highlands of Chhattisgarh.
2. It flows 860 km anda empties into the Bay of Bengal.
3. It drains the region of Maharashtra, Chhattisgarh, Jharkhand and Odisha.

The Krishna Basin

1. The Krishna River rises from Mahabaleshwar and flows 1400 km before emptying into the Bay of Bengal.
2. The major tributaries of Krishna river are Tungabhadra, Koyana, Ghatprabha, Musi and Bhima.
3. It drains the parts of Maharasthra, Karnataka and Andhra Pradesh.

The Kaveri Basin

1. The Kaveri river rises from Brahmagri range and empties into the Bay of Bengal.
2. It is 760 km long.
3. The major tributaries of Kaveri river are Amravati, Bhavani, Hemavati and  Kabini.
4. Its  basin  drains  parts  of Karnataka, Kerala and Tamil Nadu.

Lakes

1. A large water body surrounded by the land is known as a lake.
2. Some are permanent and others contain water during rainy season. The rain-fed lakes are mostly found in semi-arid regions.
3. Lakes can formed by the works of glaciers and ice sheets, wind, river and human activities.

Types of Lakes:
Ox-bow Lake
An ox bow lake appears when a meandering river forms a cut-off from the mainstream.

Lagoon
A lagoon is formed by spits and bars in coastal areas. For example, Chilika lake, Pulicat lake and Kolleru lake.

Salt Water Lake
A salt water lake is mostly found in semi-arid region. Example: Sambhar lake.

Glacial Lake (Fresh Water Lake)
A glacial lake is formed by melting of glacier. For example, Wular lake, Dal lake, Bhimtal, Nainital, Barapani and Loktak lake.
Wular lake is the largest freshwater lake in India.

Man Made Lakes
It is formed due to human intervention. For example, Gobind Sagar Lake (Himachal Pradesh).

Benefits of a Lake:

1. It helps in flood prevention by regulating flow of a river.
2. It can also be used for generating hydel power.
3. It maintains aquatic ecosystem and famous among eco-tourists.