The Drainage & River system of India : Geography notes for competitive (SSC) exams

The drainage system of India is one of the most complex and diverse in the world. It is influenced by the country's varied topography, climate, and geological features. The Indian drainage system can be broadly classified into two major categories: the Himalayan drainage system and the Peninsular drainage system.

The Himalayan drainage system is made up of three major river systems: the Indus, the Ganga, & the Brahmaputra. These rivers originate from the snow-capped peaks of the Himalayas and flow through the northern plains of India before draining into the Bay of Bengal. The Himalayan rivers are perennial, meaning that they flow throughout the year, even during the dry season. This is because the melting snow from the Himalayas feeds them.

The Peninsular drainage system comprises several smaller rivers that originate from the Western Ghats and Eastern Ghats and flow into the Bay of Bengal and Arabian Sea, respectively. The Peninsular rivers are rainfed, meaning they depend on rainfall for their flow. This is why they tend to be dry during the dry season.

Indian Rivers

The Indian drainage system plays a vital role in the country's economy, society, and environment. It provides water for irrigation, drinking, and industrial use. It also helps to regulate the climate and prevent floods. The Indian drainage system is also home to a rich diversity of aquatic life.

 

Drainage System

Definition: The drainage system involves the movement of surface water primarily through rivers.

Drainage Basin: Small streams (tributaries) converge to form the main river, which eventually empties into a larger body of water like a lake, sea, or ocean. The region drained by a single river system is known as a drainage basin.

The world’s largest drainage basin is of the Amazon River

India's largest Drainage basin is the Ganga basin.

Tributary: A stream or river that flows into a larger river is called a tributary. The Yamuna River is an example of a tributary that flows into the Ganges River in India.

Delta: A triangular-shaped land at the mouth of a river, created by the deposition of silt, sand, and small rocks carried downstream by the river, is called a delta. The Ganga Delta is an example of a delta, formed at the mouth of the Ganges River in Bangladesh and India.

Estuary: An estuary is a partially enclosed coastal body of water where the salty tidal water mixes with the freshwater of a river. The Narmada River forms an estuary where it meets the Arabian Sea in Gujarat, India.

Drainage System of India

The drainage system of India is characterized by a vast network of rivers, lakes, and other water bodies that contribute to the country's water resources. The major rivers in India, such as the Ganges, Brahmaputra, Yamuna, and Godavari, play a crucial role in the drainage system. The rivers flow through various regions, forming extensive river basins and contributing to irrigation, transportation, and hydroelectric power generation. The diverse topography, including the Himalayas, Western Ghats, and Eastern Ghats, influences the drainage patterns across the country. Additionally, India's monsoon climate significantly affects the flow of water and the overall drainage system.

Himalayan River System:

1. Perennial rivers in India, such as the Indus, Ganges and Brahmaputra, have their sources in glaciers, ensuring a continuous flow of water throughout the year.
2. The rivers in India have formed valleys over time through the process of erosion, shaping the landscape and creating diverse landforms.
3. The rivers in India, particularly those flowing through fertile plains, provide ideal conditions for irrigation, supporting agricultural activities in the region.
4. Many rivers in India have meandering courses that gradually shift over time due to natural processes, impacting the surrounding landscape and human settlements.

The major Himalayan rivers in India, namely the Indus, Ganga, and Brahmaputra, are characterized by their length and the presence of numerous significant tributaries. A river, along with its tributaries, is collectively referred to as a river system.

The Indus River System

• The river Indus originates in Tibet near Lake Mansarovar and enters India in Ladakh.
• It forms a picturesque gorge in Ladakh and receives several tributaries, including the Zaskar, Nubra, Shyok, and Hunza rivers in the Kashmir region.
• The Indus flows through Baltistan and Gilgit and emerges from the mountains at Attock.
• The Satluj, Beas, Ravi, Chenab, and Jhelum rivers join together to enter the Indus near Mithankot in Pakistan.
  The Indus then flows southwards and eventually reaches the Arabian Sea, east of Karachi.
• The Indus Plain has a gentle slope.
• The total length of the Indus is approximately 2900 km, making it one of the longest rivers in the world.
• Around one-third of the Indus Basin is located in India, including Ladakh, Jammu and Kashmir, Himachal Pradesh, and Punjab, while the remaining portion is in Pakistan.
  
  

The Indus Waters Treaty

The Indus Waters Treaty is a water-sharing agreement signed between India and Pakistan in 1960. Here are some details of the treaty:

India can use only 20 percent of the total water carried by the Indus River system. This water is used for irrigation in Punjab, Haryana, and the southern and western parts of Rajasthan.

• The treaty was signed on September 19, 1960, in Karachi, Pakistan.
• The treaty was brokered by the World Bank as a result of tensions between India and Pakistan over water sharing.
• The treaty allocated the three eastern rivers - Ravi, Beas, and Sutlej - to India for unrestricted use.
• The three western rivers - Indus, Jhelum, and Chenab - were allocated to Pakistan, with India given the right to use their waters for limited purposes such as irrigation, domestic use, and non-consumptive uses.
• The treaty established the Permanent Indus Commission (PIC), consisting of representatives from both India and Pakistan, to resolve any disputes arising from the implementation of the treaty.
• The treaty also provided for the sharing of data and information between the two countries on the flow of water in the rivers.
• The treaty is considered one of the most successful water-sharing agreements globally, as it has remained in force despite several conflicts between India and Pakistan.

The Ganga River System

• The headwaters of the Ganga River, known as the Bhagirathi, are fed by the Gangotri Glacier. It is joined by the Alaknanda River at Devaprayag in Uttarakhand.
• The Ganga River emerges from the mountains onto the plains at Haridwar.
• The Ganga is joined by several tributaries from the Himalayas, including major rivers like the Yamuna, Ghaghara, Gandak, and Kosi.
• The Yamuna River originates from the Yamunotri Glacier in the Himalayas and flows parallel to the Ganga. It meets the Ganga as a right bank tributary at Allahabad.
• The Ghaghara, Gandak, and Kosi rivers rise in the Nepal Himalayas. They are known for causing annual floods in parts of the northern plains, resulting in damage to life and property. However, these floods also enrich the soil for agricultural purposes.
• The Chambal, Betwa, and Son rivers are major tributaries that come from the peninsular uplands. They originate from semi-arid areas and have shorter courses. These rivers do not carry as much water as the Himalayan rivers.
• The Chambal River joins the Yamuna River near Etawah in Uttar Pradesh before eventually flowing into the Ganga.
• The Betwa River joins the Yamuna River near Hamirpur in Uttar Pradesh before ultimately merging with the Ganga.
• The Son River, after flowing through Madhya Pradesh and Bihar, joins the Ganga near Patna in Bihar.
• The Ganga River is enlarged by its right and left bank tributaries as it flows eastwards until Farakka in West Bengal.
• The river bifurcates at Farakka, with the Bhagirathi-Hooghly flowing southwards through the deltaic plains to the Bay of Bengal, and the mainstream flowing southwards into Bangladesh and joining with the Brahmaputra River.
• Downstream, the river is known as the Meghna and flows into the Bay of Bengal. The delta formed by these rivers is known as the Sundarban Delta.
• The total length of the Ganga River is over 2500 km.
  The Ganga River system forms a dendritic drainage pattern, characterized by the branching of streams and tributaries resembling the branches of a tree.
• Ambala is located on the water divide between the Indus and Ganga river systems.
• The plains stretching from Ambala to the Sundarban Delta cover nearly 1800 km, but the slope only falls by around 300 meters. This results in the river developing large meanders.

The Namami Gange Programme is a flagship initiative of the Indian government approved in June 2014. Its primary goal is to address pollution-related issues and restore the ecological balance of the Ganga River. The program aims to achieve effective pollution abatement, conservation, and rejuvenation of the Ganga River. It is an integrated conservation mission that involves multiple stakeholders, including central and state governments, local communities, and non-governmental organizations. The program includes various components such as sewage treatment infrastructure, riverfront development, river surface cleaning, and afforestation. The Namami Gange program emphasizes public participation and awareness campaigns to promote behavioral changes toward the conservation of the Ganga River. It is seen as a comprehensive and integrated approach to restoring the ecological and cultural significance of the Ganga River. More information about the program can be found on the Official Govt. page of the Namami Ganga Initiative

 About Sundarban Delta:

The Sundarban Delta, located in the Bay of Bengal, is the largest mangrove forest in the world and a UNESCO World Heritage Site. Here are some Details about the Sundarban Delta:

1. Location: The Sundarban Delta is situated in the southern part of Bangladesh and the Indian state of West Bengal.
2. Size: The delta covers an area of approximately 10,000 square kilometers, with about 60% in Bangladesh and 40% in India.
3. Mangrove Forest: It is renowned for its dense mangrove forests, which are adapted to survive in brackish water conditions.
4. Biodiversity: The Sundarban Delta is home to a rich and diverse ecosystem, including various species of flora and fauna. It is known for its population of Bengal tigers, which are adapted to the mangrove habitat.
5. Royal Bengal Tiger: The Sundarban Delta is one of the last strongholds of the endangered Royal Bengal Tiger. It is estimated that around 400 tigers inhabit the delta.
6. Unique Flora: The Sundarban Delta is characterized by its unique vegetation, including Sundari trees (Heritiera fomes), which give the delta its name.
7. Wildlife: Apart from tigers, the delta is home to other wildlife species such as estuarine crocodiles, Indian rock pythons, spotted deer, and various bird species.
8. Importance: The Sundarban Delta plays a crucial role in protecting the coastlines from erosion and acts as a natural barrier against cyclones and tidal waves.
9. Human Settlements: The delta is inhabited by local communities who rely on the delta's resources for their livelihoods, including fishing and honey collection.
10. Conservation Efforts: Both Bangladesh and India have implemented conservation measures to protect the Sundarban Delta, including the establishment of national parks and wildlife sanctuaries.

The Brahmaputra River System

• The Brahmaputra River originates in Tibet, east of Mansarowar Lake, close to the sources of the Indus and Satluj rivers.
• It is slightly longer than the Indus River and most of its course lies outside of India.
• The river flows eastwards parallel to the Himalayas.
  Upon reaching Namcha Barwa, a mountain with a height of 7757 m, the Brahmaputra takes a 'U' turn and enters India in Arunachal Pradesh through a gorge.
• In Arunachal Pradesh, it is known as the Dihang River and is joined by tributaries such as the Dibang, Lohit, and several others.
• The confluence of these tributaries forms the Brahmaputra River in Assam.
• The Brahmaputra River carries a smaller volume of water and less silt in Tibet, where it is cold and dry.
• In India, the river passes through a region of high rainfall, carrying a large volume of water and a considerable amount of silt.
• The Brahmaputra River has a braided channel in its entire length in Assam, forming many riverine islands.
  
  
• The world's largest riverine island formed by the Brahmaputra River is Majuli.
• Every year during the rainy season, the Brahmaputra River overflows its banks, causing widespread devastation due to floods in Assam and Bangladesh.
• Unlike other north Indian rivers, the Brahmaputra River has huge deposits of silt on its bed, causing the riverbed to rise.
• The river also frequently shifts its channel.
• The Brahmaputra is known as the Tsang Po in Tibet and Jamuna in Bangladesh

The Peninsular Rivers

The Western Ghats in Peninsular India form the main water divide, running from north to south near the western coast. The major rivers of the Peninsula, like the Mahanadi, Godavari, Krishna, and Kaveri, flow eastwards and drain into the Bay of Bengal, forming deltas at their mouths. On the other hand, there are smaller streams that flow west of the Western Ghats. The Narmada and Tapi rivers are the only long rivers that flow west and create estuaries. The drainage basins of the peninsular rivers are relatively smaller in size.

The Narmada Basin

• The Narmada River originates in the Amarkantak hills in Madhya Pradesh.
• It flows towards the west in a rift valley formed due to faulting.
• The Narmada River creates several picturesque locations on its way to the sea.
• The Marble Rocks near Jabalpur is one such location, where the river flows through a deep gorge.
• Another notable location is the Dhuadhar Falls, where the river plunges over steep rocks.
• The tributaries of the Narmada River are generally short and join the mainstream at right angles. 
• The Narmada basin covers parts of Madhya Pradesh and Gujarat.

The Tapi Basin

• The Tapi River originates in the Satpura ranges, in the Betul district of Madhya Pradesh.
• It flows in a rift valley parallel to the Narmada River, but it is much shorter in length.
• The Tapi River basin covers parts of Madhya Pradesh, Gujarat, and Maharashtra.
• The river flows through several major cities, including Surat and Vadodara in Gujarat and Bhusawal and Jalgaon in Maharashtra.
• The Tapi River empties into the Gulf of Khambhat, which is an inlet of the Arabian Sea.
• The river is about 724 km long and has several tributaries, including the Purna River, Girna River, and Panzara River.
• The Tapi River is an important source of water for irrigation, drinking, and industrial use in the states it flows through.

The Godavari Basin

• The Godavari River is the largest Peninsular river, rising from the slopes of the Western Ghats in the Nasik district of Maharashtra.
• It has a length of about 1428 km and drains into the Bay of Bengal.
• The Godavari River basin is the largest among the peninsular rivers and covers parts of Maharashtra, Madhya Pradesh, Odisha, and Andhra Pradesh.
• About 50% of the basin area lies in Maharashtra.
  The Godavari River is joined by several tributaries, including the Purna, Wardha, Pranhita, Manjra, Wainganga, and Penganga. The last three tributaries are very large.
• The Godavari River is also known as the Dakshin Ganga due to its length and the area it covers.
• The river plays a crucial role in agriculture and irrigation in the states it flows through.

The Mahanadi Basin

• The Mahanadi River rises in the highlands of Chhattisgarh and flows through Odisha before reaching the Bay of Bengal. The basin covers parts of Maharashtra, Chhattisgarh, Jharkhand, and Odisha.
• The length of the Mahanadi River is about 860 km.
• The Mahanadi is joined by several tributaries, including the Seonath, Hasdeo, Mand, Ib, Ong, Tel, and Jonk.
• The Mahanadi River flows through a rift valley formed due to faulting. This gives it a unique geological characteristic.
• The Mahanadi Basin is significant for agriculture as it provides water for irrigation in the surrounding regions. The basin is also important for hydropower generation.
• The construction of dams and reservoirs on the Mahanadi River, such as the Hirakud Dam, has helped in water storage, irrigation, and flood control.
• The Mahanadi Basin supports a rich ecosystem with diverse flora and fauna. It is home to several wildlife sanctuaries and national parks, including the Satkosia Tiger Reserve.

The Krishna Basin

• The Krishna River rises from a spring near Mahabaleshwar in the Western Ghats.
• The Krishna River flows for about 1400 km before reaching the Bay of Bengal.
• The Krishna River is joined by several tributaries, including the Tungabhadra, the Koyana, the Ghatprabha, the Musi, and the Bhima.
• The Krishna Basin covers parts of Maharashtra, Karnataka, and Andhra Pradesh.
• The Krishna River Basin Organization (KRBO) is responsible for the planning, development, and management of water resources in the Krishna Basin. It ensures equitable distribution of water among different states and stakeholders.
• Several dams and reservoirs have been constructed on the Krishna River and its tributaries for water storage, irrigation, and hydropower generation. Examples include the Almatti Dam, Nagarjuna Sagar Dam, and Srisailam Dam.
• It is home to several wildlife sanctuaries and national parks, including the Nagarjunsagar-Srisailam Tiger Reserve.
• The Shivasamudram Falls is the second biggest waterfall in India, formed by the river Kaveri. The hydroelectric power generated from the falls is supplied to Mysuru, Bengaluru, and the Kolar Gold Fields.

Lakes 

A lake is a body of water that is surrounded by land and not connected to the ocean except by rivers or streams. Lakes are typically much larger and deeper than ponds, which are also water-filled basins on land.

Type of Lakes

Natural lakes: These lakes are formed by natural processes, such as tectonic activity, glacial activity, or volcanic activity. Examples of natural lakes in India include Wular Lake, Chilika Lake, and Lonar Lake.
Artificial lakes: These lakes are created by human beings, such as by building dams or reservoirs. Examples of artificial lakes in India include Upper Lake, Hirakud Dam, and Tehri Dam.

Largest Lakes

1. Largest natural lake: Wular Lake (Jammu and Kashmir)
2. Largest saline water lake: Chilika Lake (Odisha)
3. Longest lake: Vembanad Lake (Kerala)
4. Highest lake: Cholamu Lake(Sikkim)

Important Lakes

Dal Lake (Jammu and Kashmir): A popular tourist destination known for its shikaras (houseboats) and floating markets.
Chilika Lake (Odisha): A Ramsar wetland and home to a variety of migratory birds, including flamingos, pelicans, and ibises.
Loktak Lake (Manipur): Home to a floating island called Phumdi and a popular tourist destination for its boat cruises, fishing, and birdwatching.
Pangong Tso (Ladakh): A high-altitude lake known for its stunning beauty and home to a variety of migratory birds.
Upper Lake (Madhya Pradesh): The largest artificial lake in Asia and a popular tourist destination for its boating and fishing.

Other Important Lakes

• Bhimtal Lake (Uttarakhand)
• Vembanad Lake (Kerala)
• Pushkar Lake (Rajasthan)
• Lonar Lake (Maharashtra)
• Sambhar Lake (Rajasthan)
• Nal Sarovar Bird Sanctuary (Gujarat)
• Keoladeo National Park (Rajasthan)