NCERT Notes Class 9 Geography: Chapter 3: Drainage

NCERT Notes Class 9 Geography: Geography Class 9 Notes is an important subject in the Social Science curriculum that requires students to have a thorough understanding of the Drainage Systems in India.

Understanding these concepts well is crucial for students. These notes give a clear summary of the main topics, helping students understand the subject better.

Our Geography Notes for Class 9 help improve problem-solving skills and prepare for exams. With these notes, students can build a strong foundation in Geography and improve their problem-solving skills.

Drainage

The term drainage refers to the river system in an area. If you look at a physical map, you’ll see that smaller streams from various directions merge to form a main river. Eventually, this river flows into a larger water body like a lake, sea, or ocean.

The region drained by a single river system is called a drainage basin. When you examine a map closely, you’ll notice that elevated areas like mountains or uplands separate two drainage basins. These elevated areas act as water divides.

Drainage Systems in India

The drainage systems of India are mainly shaped by its broad relief features. Indian rivers are divided into two main groups: the Himalayan rivers and the Peninsular rivers. There are significant differences between these two groups.

The Himalayan Rivers	The Peninsular Rivers
Mostly perennial	Many are seasonal
Originate from mountain ranges	Mostly originate in the Western Ghats
Receive water from rain and melted snow	Dependent on rainfall
Long courses, cutting through mountains	Shorter and shallower courses
Form features like gorges, meanders, oxbow lakes, and deltas	Form features mainly in their floodplains

The Himalayan Rivers

The major Himalayan rivers include the Indus, the Ganga, and the Brahmaputra. When we refer to a river along with all its tributaries, we call it a river system.

The Indus River System

• Originates in Tibet, near Lake Mansarowar.
• Enters India in Ladakh, Jammu and Kashmir.
• Joined by tributaries like Zaskar, Nubra, Shyok, and Hunza.
• Emerges from mountains at Attock, Pakistan.
• Tributaries like Satluj, Beas, Ravi, Chenab, and Jhelum join in Pakistan.
• Flows southwards and eventually reaches the Arabian Sea.
• Indus plain has a gentle slope.
• Spans 2900 km, one of the longest rivers globally.
• Around one-third of the basin is in India, the rest in Pakistan.

The Ganga River System

• Originates as Bhagirathi, fed by Gangotri Glacier, joined by Alaknanda at Devaprayag.
• Emerges onto the plains at Haridwar.
• Joined by tributaries like Yamuna, Ghaghara, Gandak, and Kosi.
• Yamuna rises from Yamunotri Glacier, flows parallel to Ganga, and meets at Allahabad.
• Ghaghara, Gandak, and Kosi flood northern plains annually.
• Peninsular tributaries include Chambal, Betwa, and Son, joining from semi-arid areas.
• Enlarged, flows eastwards till Farakka in West Bengal.
• Bifurcates at Farakka; Bhagirathi-Hooghly flows southwards, while mainstream continues into Bangladesh.
• Joins Brahmaputra and forms Sunderban delta before flowing into the Bay of Bengal.
• Ganga’s length exceeds 2500 km.
• Forms large meanders due to the gentle slope of plains.

The Brahmaputra River System

• The Brahmaputra River originates in Tibet, near Mansarowar Lake.
• It flows eastwards parallel to the Himalayas.
• Upon reaching Namcha Barwa, it takes a ‘U’ turn and enters India in Arunachal Pradesh through a gorge.
• In Arunachal Pradesh, it is known as the Dihang.
• The Brahmaputra is joined by tributaries like the Dibang and the Lohit in Assam.
• In Tibet, the river carries less water and silt due to the cold and dry climate.
• In India, where it passes through a region with high rainfall, it carries a large volume of water and silt.
• The Brahmaputra has a braided channel throughout its length in Assam.
• It forms numerous riverine islands along its course.
• Every year during the rainy season, the river floods its banks, causing extensive damage in Assam and Bangladesh.
• Unlike other north Indian rivers, the Brahmaputra accumulates huge deposits of silt on its bed, leading to the elevation of the riverbed and frequent changes in its channel.

The Peninsular Rivers

• Formation of Water Divide: The main water divide in Peninsular India is formed by the Western Ghats, running from north to south close to the western coast.
• Direction of Flow: Most 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 form deltas at their mouths.
• Minor Streams: Numerous small streams flow west of the Western Ghats.
• Exceptional Rivers: The Narmada and the Tapi are the only long rivers that flow west and make estuaries.
• Drainage Basin Size: The drainage basins of the peninsular rivers are relatively small.

The Narmada Basin

• Source: The Narmada rises in the Amarkantak hills in Madhya Pradesh.
• Flow Direction: It flows towards the west in a rift valley formed due to faulting.
• Landscapes: Along its path to the sea, the Narmada creates picturesque locations such as the ‘Marble Rocks’ near Jabalpur and the ‘Dhuadhar falls’ where the river plunges over steep rocks.
• Tributaries: All tributaries of the Narmada are very short, joining the main stream at right angles.
• Geographical Coverage: The Narmada basin covers parts of Madhya Pradesh and Gujarat.

The Tapi Basin

• Source: The Tapi rises in the Satpura ranges, in the Betul district of Madhya Pradesh.
• Flow Direction: It flows in a rift valley parallel to the Narmada but is much shorter in length.
• Geographical Coverage: Its basin covers parts of Madhya Pradesh, Gujarat, and Maharashtra.
• Coastal Plains: The coastal plains between Western Ghats and the Arabian Sea are narrow, resulting in short coastal rivers. Major west-flowing rivers include the Sabarmati, Mahi, Bharathpuzha, and Periyar.

The Godavari Basin

• Source: The Godavari rises from the slopes of the Western Ghats in the Nasik district of Maharashtra.
• Size: It is the largest Peninsular river with a length of about 1500 km.
• Drainage Basin: The basin covers parts of Maharashtra, Madhya Pradesh, Odisha, and Andhra Pradesh. About 50 percent of the basin area lies in Maharashtra.
• Tributaries: The Godavari is joined by numerous tributaries, including the Purna, the Wardha, the Pranhita, the Manjra, the Wainganga, and the Penganga. The last three tributaries are very large.

The Mahanadi Basin

• Source: The Mahanadi rises in the highlands of Chhattisgarh.
• Flow Path: It flows through Odisha to reach the Bay of Bengal.
• Length: The length of the river is about 860 km.
• Drainage Basin: Its drainage basin is shared by Maharashtra, Chhattisgarh, Jharkhand, and Odisha.

The Krishna Basin

• Source: The Krishna rises from a spring near Mahabaleshwar.
• Length: It flows for about 1400 km before reaching the Bay of Bengal.
• Tributaries: Tributaries of the Krishna include the Tungabhadra, the Koyana, the Ghatprabha, the Musi, and the Bhima.
• Geographical Coverage: Its drainage basin is shared by Maharashtra, Karnataka, and Andhra Pradesh.

The Kaveri Basin

• Source: The Kaveri rises in the Brahmagri range of the Western Ghats.
• Length: Total length of the river is about 760 km.
• Tributaries: Major tributaries are the Amravati, Bhavani, Hemavati, and Kabini.
• Drainage Area: Its basin drains parts of Karnataka, Kerala, and Tamil Nadu.

Other Rivers:

Smaller rivers flowing towards the east include the Damoder, the Brahmani, the Baitarni, and the Subarnrekha.

Lakes

India has a variety of lakes, each differing in size and characteristics:

• Most lakes are permanent, while some contain water only during the rainy season.
• Glaciers and ice sheets have contributed to the formation of certain lakes.
• Wind, river action, and human activities have also created lakes.
• Lakes like those in Srinagar and Nainital attract tourists.

Different types of lakes in India include:

• Ox-bow Lakes: These form when a meandering river across a floodplain creates cut-offs.
• Lagoons: Spits and bars in coastal areas form lagoons, such as Chilika Lake, Pulicat Lake, and Kolleru Lake.
• Seasonal Lakes: Lakes in inland drainage regions, like Sambhar Lake in Rajasthan, are sometimes seasonal.
• Glacial Lakes: Most freshwater lakes, such as Wular Lake in Jammu and Kashmir, are in the Himalayan region and are of glacial origin.

Importance of Lakes:

• They regulate river flow and prevent flooding during heavy rains.
• Lakes maintain an even flow of water during the dry season.
• They can be utilized for hydel power generation.
• Lakes moderate the climate, support aquatic ecosystems, enhance natural beauty, and provide recreational opportunities.

Role of Rivers in the Economy

From ancient times, riverbanks have drawn settlers due to the fundamental importance of water from rivers, which serves as a basic natural resource essential for various human activities.

• Rivers play a important role in irrigation, facilitating the cultivation of crops and supporting agricultural livelihoods.
• Rivers also contribute to hydro-power generation, harnessing the energy of flowing water to produce electricity, thereby supporting industrial and domestic needs.

River Pollution

The rising demand for water from rivers for domestic, municipal, industrial, and agricultural purposes is negatively impacting water quality. Rivers are becoming increasingly polluted due to the discharge of untreated sewage and industrial effluents. To address this issue, various action plans have been launched to clean up the rivers and mitigate pollution.

Related Links

• Notes Chapter 1: Geography as a Discipline
• Land Resources and Agriculture| Class 12 Geography Notes
• Growth and Development| Class 12 Geography Notes
• Branches of Geography (Based on Regional Approach)| Class 11 Geography Notes

FAQs on NCERT Notes Class 9 Geography: Chapter 3: Drainage

What is drainage in geography?

Drainage refers to the river system of an area, where small streams from different directions converge to form larger rivers that ultimately drain into a larger water body such as a lake, sea, or ocean.

What is a drainage basin?

A drainage basin is the area of land drained by a single river system, including its tributaries. It is also known as a watershed or catchment area.

What are the major types of rivers in India?

In India, rivers are broadly classified into two main types: the Himalayan rivers and the Peninsular rivers.

What are Himalayan rivers?

Himalayan rivers originate from the Himalayan mountain range and are characterized by their perennial flow, which means they have water throughout the year. Examples include the Indus, Ganga, and Brahmaputra rivers.

What are Peninsular rivers?

Peninsular rivers flow through the Peninsular plateau of India. They are often seasonal, with their flow dependent on rainfall. Examples include the Mahanadi, Godavari, Krishna, and Kaveri rivers.

How do Himalayan rivers differ from Peninsular rivers?

Himalayan rivers are generally perennial and receive water from rain as well as melted snow, while Peninsular rivers are often seasonal and depend on rainfall for their flow.