Revision Notes for Chapter 3 Drainage Class 9 Geography
CBSE NCERT Revision Notes1
Drainage
Answer
• Drainage describes the river system of an area.
• The area drained by a single river system is called a drainage basin.
• Any upland or a mountain separating two adjoining drainage basins is known as water divide.
• The area drained by a single river system is called a drainage basin.
• Any upland or a mountain separating two adjoining drainage basins is known as water divide.
2
Drainage Systems in India
Answer
• The Indian rivers are divided into two major groups:
→ the Himalayan rivers
→ the Peninsular rivers
• Features of Himalayan rivers
→ These are perennial (flow all years).
→ These rivers receive water from rain as well as from melted snow from the lofty mountains.
→ The Himalayan rivers have long courses from their source to the sea.
→ The Himalayan rivers form meanders, oxbow lakes, and many other depositional features in their floodplains.
• Features of Peninsular rivers:
→ They are seasonal.
→ the Himalayan rivers
→ the Peninsular rivers
• Features of Himalayan rivers
→ These are perennial (flow all years).
→ These rivers receive water from rain as well as from melted snow from the lofty mountains.
→ The Himalayan rivers have long courses from their source to the sea.
→ The Himalayan rivers form meanders, oxbow lakes, and many other depositional features in their floodplains.
• Features of Peninsular rivers:
→ They are seasonal.
→ Their flow is dependent on rainfall.
→ The Peninsular rivers have shorter and shallower courses as compared to their Himalayan rivers.
→ Most of the rivers of peninsular India originate in the Western Ghats and flow towards the Bay of Bengal.
3
The Himalayan Rivers
Answer
• The Indus, the Ganga and the Brahmaputra are major Himalayan rivers.
• A river alongwith its tributaries may be called a river system.
• A river alongwith its tributaries may be called a river system.
4
The Indus River System
Answer
• Source: The river Indus rises in Tibet, near Lake Mansarowar.
• It enters India in the Ladakh district of Jammu and Kashmir flowing west.
• Tributaries of Indus:
→ The Zaskar, the Nubra, the Shyok and the Hunza join it in the Kashmir region.
→ The Satluj, the Beas, the Ravi, the Chenab and the Jhelum join together to enter the Indus near Mithankot in Pakistan.
• The Indus plain has a very gentle slope.
• Total length: 2900 km
• A third of the Indus basin is located in India in the states of Jammu and Kashmir, Himachal Pradesh and the Punjab and the rest is in Pakistan.
• It enters India in the Ladakh district of Jammu and Kashmir flowing west.
• Tributaries of Indus:
→ The Zaskar, the Nubra, the Shyok and the Hunza join it in the Kashmir region.
→ The Satluj, the Beas, the Ravi, the Chenab and the Jhelum join together to enter the Indus near Mithankot in Pakistan.
• The Indus plain has a very gentle slope.
• Total length: 2900 km
• A third of the Indus basin is located in India in the states of Jammu and Kashmir, Himachal Pradesh and the Punjab and the rest is in Pakistan.
5
The Ganga River System
Answer
• Source: The headwaters of the Ganga, called the ‘Bhagirathi’ is fed by the Gangotri Glacier.
• Tributaries of Ganga:
→ Alaknanda joined at Devaprayag in Uttarakhand.
→ The Yamuna rises from the Yamunotri Glacier in the Himalayas joins at Allahabad.
→ the Ghaghara, the Gandak and the Kosi rise in the Nepal Himalaya.
• Tributaries of Ganga:
→ Alaknanda joined at Devaprayag in Uttarakhand.
→ The Yamuna rises from the Yamunotri Glacier in the Himalayas joins at Allahabad.
→ the Ghaghara, the Gandak and the Kosi rise in the Nepal Himalaya.
→ the Chambal, the Betwa and the Son rise from semi-arid areas.
• The river bifurcates Farakka in West Bengal.
→ The Bhagirathi-Hooghly(a distributary) flows southwards through the deltaic plains to the Bay of Bengal.
→ The mainstream, flows southwards into Bangladesh and is joined by the Brahmaputra.
• Total length: 2500 km
• Sunderban Delta: The delta formed by the rivers the Ganga and the Brahmaputra is known as the Sunderban delta.
• The river bifurcates Farakka in West Bengal.
→ The Bhagirathi-Hooghly(a distributary) flows southwards through the deltaic plains to the Bay of Bengal.
→ The mainstream, flows southwards into Bangladesh and is joined by the Brahmaputra.
• Total length: 2500 km
• Sunderban Delta: The delta formed by the rivers the Ganga and the Brahmaputra is known as the Sunderban delta.
6
The Brahmaputra River System
Answer
• Source: The Brahmaputra rises in Tibet east of Mansarowar lake very close to the sources of the Indus and the Satluj.
• Tributaries of Brahmaputra:
• Tributaries of Brahmaputra:
→ Dibang, the Lohit
• Flows eastwards parallel to the Himalayas. it takes a ‘U’ turn on reaching the Namcha Barwa and enters India in Arunachal Pradesh through a gorge.
→ Here, it is called the Dihang and it is joined by the Dibang, the Lohit and many other tributaries.
• In Tibet, the river carries a smaller volume of water and less silt as it is a cold and a dry area.
→ In India, it passes through a region of high rainfall. and the river carries a large volume of water and considerable amount of silt
• It 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.
• Majuli is the world’s largest riverine island formed by the Brahmaputra.
• Flows eastwards parallel to the Himalayas. it takes a ‘U’ turn on reaching the Namcha Barwa and enters India in Arunachal Pradesh through a gorge.
→ Here, it is called the Dihang and it is joined by the Dibang, the Lohit and many other tributaries.
• In Tibet, the river carries a smaller volume of water and less silt as it is a cold and a dry area.
→ In India, it passes through a region of high rainfall. and the river carries a large volume of water and considerable amount of silt
• It 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.
• Majuli is the world’s largest riverine island formed by the Brahmaputra.
7
The Peninsular Rivers
Answer
• The main water divide in Peninsular India is formed by the Western Ghats.
• 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.
• The Narmada and the Tapi are the only long rivers, which flow west and make esturies.
• 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.
• The Narmada and the Tapi are the only long rivers, which flow west and make esturies.
8
The Narmada Basin
Answer
• Source: It rises in the Amarkantak hills in Madhya Pradesh.
• It flows towards the west in a rift valley formed due to faulting.
• All the tributaries of the Narmada are very short and most of these join the main stream at right angles.
• The Narmada basin covers parts of Madhya Pradesh and Gujarat.
• It flows towards the west in a rift valley formed due to faulting.
• All the tributaries of the Narmada are very short and most of these join the main stream at right angles.
• The Narmada basin covers parts of Madhya Pradesh and Gujarat.
9
The Tapi Basin
Answer
• Source: It 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.
• Other West flowing rivers: Sabarmati, Mahi, Bharathpuzha and Periyar.
• 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.
• Other West flowing rivers: Sabarmati, Mahi, Bharathpuzha and Periyar.
10
The Godavari Basin
Answer
• Source: It rises from the slopes of the Western Ghats in the Nasik district of Maharashtra.
• It is the largest Peninsular river.
• Tributaries of Godavari:
→ the Purna, the Wardha, the Pranhita, the Manjra, the Wainganga and the Pengang.
• The basin covers parts of Maharashtra, Madhya Pradesh, Odisha and Andhra Pradesh.
• It drains into the Bay of Bengal.
• Total length: 1500 km
• Because of its length and the area it covers, it is also known as the ‘Dakshin Ganga’.
• It is the largest Peninsular river.
• Tributaries of Godavari:
→ the Purna, the Wardha, the Pranhita, the Manjra, the Wainganga and the Pengang.
• The basin covers parts of Maharashtra, Madhya Pradesh, Odisha and Andhra Pradesh.
• It drains into the Bay of Bengal.
• Total length: 1500 km
• Because of its length and the area it covers, it is also known as the ‘Dakshin Ganga’.
11
The Mahanadi Basin
Answer
• Source: The Mahanadi rises in the highlands of Chhattisgarh.
• It flows through Odisha to reach the Bay of Bengal.
• Its drainage basin is shared by Maharashtra, Chhattisgarh, Jharkhand, and Odisha.
• Total length: 860 km
• It flows through Odisha to reach the Bay of Bengal.
• Its drainage basin is shared by Maharashtra, Chhattisgarh, Jharkhand, and Odisha.
• Total length: 860 km
12
The Krishna Basin
Answer
• It rises from spring near Mahabaleshwar.
• Tributaries of Krishna:
→ The Tungabhadra, the Koyana, the Ghatprabha, the Musi and the Bhima.
• Total length: 1400 km
• Its drainage basin is shared by Maharasthra, Karnataka and Andhra Pradesh.
• Tributaries of Krishna:
→ The Tungabhadra, the Koyana, the Ghatprabha, the Musi and the Bhima.
• Total length: 1400 km
• Its drainage basin is shared by Maharasthra, Karnataka and Andhra Pradesh.
13
The Kaveri Basin
Answer
• Source: It rises in the Brahmagri range of the Western Ghats.
• Tributaries of Kaveri:
→ Amravati, Bhavani, Hemavati and Kabini
• Total length: 760 km
• It reaches the Bay of Bengal in south of Cuddalore, in Tamil Nadu.
• Other east flowing rivers: The Damoder, the Brahmani, the Baitarni and the Subarnrekha.
• Tributaries of Kaveri:
→ Amravati, Bhavani, Hemavati and Kabini
• Total length: 760 km
• It reaches the Bay of Bengal in south of Cuddalore, in Tamil Nadu.
• Other east flowing rivers: The Damoder, the Brahmani, the Baitarni and the Subarnrekha.
14
Lakes
Answer
• India has many lakes which differ from each other in the size and other characteristics.
• Most lakes are permanent while some contain water only during the rainy season.
• Some of the lakes are the result of the action of glaciers and ice sheets, while the others have been formed by wind, river action, and human activities.
• A meandering river across a flood plain forms cut-offs that later develop into ox-bow lakes.
• Most of the fresh water lakes are in the Himalayan region.
• Most lakes are permanent while some contain water only during the rainy season.
• Some of the lakes are the result of the action of glaciers and ice sheets, while the others have been formed by wind, river action, and human activities.
• A meandering river across a flood plain forms cut-offs that later develop into ox-bow lakes.
• Most of the fresh water lakes are in the Himalayan region.
→ They formed when glaciers dug out a basin, which was later filled with snowmelt.
• The Wular lake in Jammu and Kashmir is the result of the tectonic activity which is the largest freshwater lake in India.
• Artificial lakes: The damming of the rivers for the generation of hydro power has also led to the formation of Lakes such as Guru Gobind Sagar.
• Importance of Lakes:
→ 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.
→ Also used for developing hydro power.
→ They moderate the climate of the surrounding.
→ maintaining the aquatic ecosystem
→ Enhance natural beauty
→ Helps in developing tourism and providing recreation.
• The Wular lake in Jammu and Kashmir is the result of the tectonic activity which is the largest freshwater lake in India.
• Artificial lakes: The damming of the rivers for the generation of hydro power has also led to the formation of Lakes such as Guru Gobind Sagar.
• Importance of Lakes:
→ 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.
→ Also used for developing hydro power.
→ They moderate the climate of the surrounding.
→ maintaining the aquatic ecosystem
→ Enhance natural beauty
→ Helps in developing tourism and providing recreation.
15
Role of Rivers in the Economy
Answer
• From ancient times. rivers banks attracted settlers as water from the rivers is a basic natural resource essential for various human activities.
• Rivers are used for irrigation, navigation and hydro-power generation.
• Rivers are used for irrigation, navigation and hydro-power generation.
16
River Pollution
Answer
• The demand for water from river is increasing to meet growing domestic, municipal, industrial and agricultural need which naturally affects the quality of water.
• More and more water is being drained out of the rivers reducing their volume.
• Also, a heavy load of untreated sewage and industrial effluents are emptied into the rivers which affects not only the quality of water but also the self-cleansing capacity of the river.
• Concern over rising pollution in our rivers led to the launching of various action plans to clean the rivers.
• More and more water is being drained out of the rivers reducing their volume.
• Also, a heavy load of untreated sewage and industrial effluents are emptied into the rivers which affects not only the quality of water but also the self-cleansing capacity of the river.
• Concern over rising pollution in our rivers led to the launching of various action plans to clean the rivers.