9 Geography Chapter 3 Drainage

Chapter Notes and Summary
Drainage
1. term drainage describes river system of an area.
2. area drained by a single river system is called a drainage basin.
3. Any elevated area such as a mountain or an upland which separates two drainage basins is known as a water divide.
4. Small streams flowing in different directions come together to form a river which ultimately drains into a large water body such as a lake or sea or an ocean.
Drainage Systems in India Indian rivers are divided into two major groups: Himalayan rivers and Peninsular rivers.
1. Himalayan Rivers
(a) Most of Himalayan rivers are perennial, which means that they have water throughout year.
(b) These rivers receive water from rain as well as from melted snow from lofty mountains.
(c) two major Himalayan rivers, Indus and Brahmaputra, originate from North of mountain ranges.
(d) They perform intensive erosional activity in their upper courses and carry huge loads of silt and sand.
2. Peninsular Rivers
(a) Peninsular Rivers are mainly seasonal and flow during rainy season.
(b) During dry season, peninsular regions have reduced flow of water.
(c) They have shallower and shorter courses.
(d) Most peninsular rivers originate in Western Ghats and flow towards Bay of Bengal.
Drainage Patterns
1. streams within a drainage basin form certain patterns, depending on slope of land, underlying rock structure and climatic conditions of area. drainage patterns are
(a) Dendritic Pattern A dendritic pattern develops when river channel follows slope of terrain.
The stream with its tributaries resemble branches of a tree and so it is called dendritic.
(b) Trellis Pattern A river, joined by its tributaries at approximately right angles, develops where hard and soft rocks exits parallel to each other.
(c) Rectangular Pattern A rectangular drainage pattern develops on a strongly jointed rocky terrain.
(d) Radial Pattern radial pattern develops when streams flow in different directions from a central peak or dome like structure.
A combination of several patterns may be found in same drainage basin.
Himalayan Rivers
1. major Himalayan rivers are Indus, Ganga and Brahmaputra.
2. rivers are long and are joined by many large and important tributaries. A river along with its tributaries is called a river system.
Indus River System
1. river Indus rises in Tibet near lake Mansarowar.
2. Flowing West, it enters India in Ladakh district of Jammu and Kashmir.
3. Several tributaries, Zanskar, Nubra, Shyok and Hunza join it in Kashmir region.
4. Indus flows through Baltistan and Gilgit and emerges from mountains at Attock in Pakistan.
5. Satluj, Beas, Ravi, Chenab and Jhelum join together to enter Indus near Mithankot in Pakistan.
6. Indus flows southwards, eventually reaching Arabian Sea east of Karachi.
7. Indus plain has a very gentle slope.
8. With a total length of 2,900 km, Indus is one of longest rivers of world.
9. A little over a third of Indus basin is located in India in states of Jammu and Kashmir, Himachal Pradesh and Punjab. rest is in Pakistan.
Ganga River System
1. headwaters of Ganga, called Bhagirathi, is fed by Gangotri glacier and joined by Alaknanda at Devaprayag in Uttarakhand to form Ganga.
2. At Haridwar Ganga emerges from mountains into plains.
3. Ganga is joined by many tributaries from Himalayas, a few of them being major rivers such as Yamuna, Ghaghara, Gandak and Kosi.
4. Ganga from Farakka in West-Bengal bifurcates into two, from where Bhagirathi-Hooghly (a distributary)
flows southwards to Bay of Bengal. main stream flows southwards into Bangladesh and is joined by Brahmaputra.
5. It forms world’s biggest delta called Sunderban delta.
The length of Ganga is 2,500 km.
Brahmaputra River System
1. Brahmaputra rises in Tibet east of Mansarowar Lake very close to sources of Indus and Satluj.
2. It is slightly longer than Indus and most of its course lies outside India.
3. On reaching Namcha Barwa (7,757 m) it takes a U turn and enters India in Arunachal Pradesh through a gorge.
4. Here it is called Dihang and it is joined by Dibang, Lohit and many others tributaries to form Brahmaputra in Assam.
5. In Tibet, it carries a smaller volume of water and less silt as it is a cold region.
6. In India, it carries a large volume of water and considerable amount of silt because it passes through an area of high rainfall.
7. During rainy season, river overflows its banks causing widespread devastation due to floods in Assam and Bangladesh.
8. It flows into Bay of Bengal and deposits a lot of silt. It shifts its channel frequentty.
Peninsular Rivers
1. main water divide in peninsular India is formed by Western Ghats which runs from north to south close to western coast.
2. Most of peninsular rivers like Mahanadi, Godavari, Krishna and Kaveri flow eastwards and drain into Bay of Bengal.
3. These rivers make deltas at their mouths.
4. Narmada and Tapi are only long rivers which flow west and make estuaries.
5. drainage basins of peninsular rivers are comparatively small in size.
Narmada Basin
1. Narmada rises in Amarkantak Hills in Madhya Pradesh.
2. It flows towards west in Rift Valley formed due to faulting.
3. Narmada creates many picturesque locations like the
‘Marble Rocks’ near Jabalpur, where Narmada flows through a deep gorge and ‘Dhuadhar falls’ where river plunges over steep rocks.
4. All tributaries of Narmada are very short and most of these join main stream at right angles.
5. Narmada basin covers parts of Madhya Pradesh and Gujarat.
Tapi Basin
1. Tapi rises in Satpura ranges in Betul district of Madhya Pradesh.
2. It flows in a Rift Valley parallel to Narmada, but it is much shorter in length.
3. Its basin covers parts of Madhya Pradesh, Gujarat and Maharashtra.
4. main west flowing rivers are Sabarmati, Mahi, Bharathpuzha and Periyar.
Godavari Basin
1. Godavari is largest peninsular river.
2. It rises from slopes of Western Ghats in Nasik district of Maharashtra.
3. Its length is about 1500 km and it drains into Bay of Bengal.
4. Its drainage basin is among largest in peninsular rivers and covers parts of Maharashtra Madhya Pradesh, Odisha and Andhra Pradesh.
5. Its tributaries are Purna, Wardha, Pranhita, Manjra, Wainganga and Penganga.
6. Because of its length and large area that it covers, it is also known as Dakshin Ganga.
Mahanadi Basin
1. Mahandi rises in high lands of Chhattisgarh.
2. It flows through Odisha to reach Bay of Bengal.
3. length of river is about 860 km.
4. Its drainage basin is shared by Maharashtra, Chhattisgarh, Jharkhand and Orrisa.
Krishna Basin
1. It rises from a spring near Mahabaleshwar and flows for about 1400 km to reach Bay of Bengal.
2. Tungabhadra, Koyana, Ghatprabha, Musi and Bhima are some of its tributaries.
3. Its drainage basin is shared by Maharashtra, Karnataka and Andhra Pradesh.
Kaveri Basin
1. Kaveri rises in Brahmagri range of Western Ghats and reaches Bay of Bengal south of Cuddalore in Tamil Nadu.
2. Total length of river is about 760 km.
3. Its main tributaries are Amravati, Bhavani, Hemavati and Kabini.
4. Its basin drains parts of Karnataka, Kerala and Tamil Nadu.
Lakes
1. India has many lakes. These differ from one another in size and other characteristics.
2. Some of lakes are result of action of glaciers and ice sheets, while others have been formed by wind or river action and human activities.
3. A meandering river across a flood plain forms cut-offs that later develop into ox-bow lakes.
4. Spits and bars form lagoons in coastal areas e.g., Chilka Lake, Pulicat Lake and Kolleru Lake.
5. Most fresh water lakes are in Himalayan region. They are mainly of glacial origin.
6. Wular Lake in Jammu and Kashmir is result of tectonic activity. It is largest fresh water lake in India.
7. Dal lake, Bhimtal, Nainital, Loktak and Barapani are some important fresh water lakes.
8. Apart from natural lakes, damming of rivers for generation of hydel power has also led to formation of lakes such as Guru Gobind Sagar (Bhakra Nangal Project).
9. Lakes are of great value to human beings because they help to regulate flow of a river.
10. During heavy rainfall lakes prevent flooding.
11. They can be used for developing hydel power.
12. They moderate climate of surroundings and maintain aquatic eco-system, enhancing natural beauty.
13. Lakes also help to develop tourism and provide recreation.
14. Inland salt water lakes are mainly found in Rajasthan e.g., Sambhar Lake. It is used for producing salt.
Role of Rivers in Economy
1. Rivers have played an important role throughout human history.
2. Water from rivers is a basic natural resource essential for various human activities.
3. Rivers provide water for irrigation.
4. They provide facility for navigation.
5. They provide water for domestic use like washing, cooking, drinking etc.
6. They help to generate hydroelectric power.
7. river banks attracted settlers from ancient times, and these settlements have now become big cities.
8. They help to moderae climate of surrounding area.
9. They help to promote fisheries.
Causes of River Pollution
1. growing domestic, municipal, industrial and agricultural demand for water from rivers naturally affects quality of water.
2. Due to this demand, more and more water is being drained out of rivers, reducing their volume.
3. Due to overuse of river water, aquatic life is affected negatively.
4. Heavy loads of untreated sewage and industrial effluents are emptied into rivers, thus polluting them.
Conservation of Rivers
1. Concern over river pollution in our rivers led to launching of various action plans to clean rivers.
2. Ganga Action Plan has been launched to cleanse and save Ganga.
3. Through newspapers, radio and TV, awareness is being generated among people about need to protect our rivers.
4. National River Conservation Plan (NRCP) was launched to protect rivers.
5. A total of 215 schemes of pollution abatement have been sanctioned. 69 schemes have been completed under NRCP.
6. A million litres of sewage is targeted to be intercepted, diverted and treated per year.

Leave a Reply

Your email address will not be published. Required fields are marked *