CLASS 9 GEOGRAPHY | Important Points and Short Notes | Chapter: 3 Drainage

 CLASS 9 GEOGRAPHY | Important Points and Short Notes | Chapter: 3 Drainage

Chapter: 3 Drainage

1. Drainage describes the river system of an area. The area drained by a single river system is called a drainage basin. Any elevated area, such as a mountain or an upland, separate two drainage basins known as a water divide.

2. The Indians rivers are divided into 2 major groups: 
(a) Himalayan rivers are perennial means that they have water throughout the year because they receive water from rain as well as from melted snow. They have long courses from their sources to the sea. In the middle and the lower courses, these rivers form meanders, oxbow lakes, and other depositional features in their floodplains.

(b)  Peninsular rivers are seasonal as the or flow is dependent on rainfall. During dry season, even the large rivers have reduces flow of water in their channels. They shorter and shallower courses. 

3. THE HIMALAYAN RIVERS
 The major Himalayan rivers are the Indus, the Ganga and the Brahmaputra. A river along width its tributaries may be called a river system.
A. THE INDUS RIVER SYSTEM

The river Indus rises in Tibet, near lake Mansarowar. Flowing west it enters India in the Ladakh district of J&K. The Indus flows southwards reaching the Arabian Sea, east of Karachi. Total length of 2900 km.

B. THE GANGA RIVER SYSTEM

The headwaters of the Ganga, called the 'Bhagirathi' is fed by the Gangotru Galcier and joined bt Alkhananda at Devaprayag in Uttarakhand. At Haridwar the ganga emerges from mountains. It is largest river basin in India.

C. THE BRAHMAPUTRA RIVER SYSTEM

The Brahmaputra rises in Tibet east of Mansarowar lake very close to the sources of the Indus and the Satluj. On reaching, Namcha Barwa(7757m), it takes U turn and enters India in Arunachal Pradesh through a gorge. In rainy season, this river over flows causing widespread devastation due to floods in Assam and Bangladesh.

4. THE PENINSULAR RIVERS

 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. The Narmada and the Tapi are the only long rivers, which flow west and make esturies. They are small in size.

A. 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. All the Tributaries join the man at right angles. It control parts of M.P. and Gujarat

B.  THE TAPI BASIN

The Tapi rises in the Satpura Ranges. IT also flows in a rift valley parallel to the Narmada but it is shorter. It cover parts M.P, Gujarat and Maharashtra.  The main west flowing rivers are Sabarmati, Mahi, Bharathpuzha and Periyar.

C. 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 1500 km. It drains into the Bay of Bengal. It is also known as the ' Dakshin Ganga'.

D. THE MAHANADI BASIN

The Mahandi rises in the highlands of Chhattisgarh. The length of the river about 860 km.  Its drainage basin is shared by Maharashtra, Chhattisgarh, Jharkhand, and Odisha.

E. THE KRISHNA BASIN

It rise from a spring near Mahabaleshwar, the Krshna length is about 1400 km. The Tungabhadra, the Koyana, the Ghatprabha, the Musi and the Bhima are some of its tributaries.

F. THE KAVERI BASIN

It rises in the Brahmagri range of the western Ghats. Total length of Kaveri is about 760 km. Its main tributaries are Amravati, Bhavani, Hemavati and Kabini.

5. LAKES

A meandering, river across a flood plain forms cut offs that later develop into ox bow lakes. sambhar lake in Rajasthan , which is a salt water lake. Its water is used for producing salt.  Most of the fresh lakes are found in Himalayan region. The wular lake in J&K . The Dal lake, Bhimtal, Nainital, Loktak and Barapani are some important fresh lakes. Generation of hydel power has also led to the formation of Lake as such as Guru Gobind Sagar.

6. ROLE OF RIVERS IN THE ECONOMY

Rivers have been of fundamental importance throughout the human history. Water from the rivers is a basic natural resource, essential for various human activities. Therefore, the river banks have attracted settlers from ancient times. A country like India, where agriculture is the major source of livelihood of the majority of its population.

7. 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. The increasing urbanisation and industrialisation do not allow it to happen and the pollution level of many rivers has been rising. “life of human beings without fresh water”.