Introduction

THE DRAINAGE SYSTEM

• • The drainage system is an integrated system of tributaries and a trunk stream that collects and funnel surface water to the sea, lake, or some other body of water.

• • The total area that contributes water to a single drainage system is known as a drainage basin.

• • A geometric arrangement of streams in a region, determined by slope, differing rock resistance to weathering and erosion, climate, hydrologic variability, and structural controls of the landscape is known as a drainage pattern.

• • Thus, a drainage pattern refers to a design in which a river and its tributaries form together, from its source to its mouth.

• • India has the following drainage patterns:

• • • The Antecedent or Inconsequent Drainage: The rivers that existed before the upheaval of the Himalayas and cut their courses southward by making gorges in the mountains are known as the antecedent rivers.

• • • Consequent Rivers: The rivers which follow the general direction of the slope are known as the consequent rivers. Most of the rivers of peninsular India are consequent rivers.

• • • Subsequent Rivers: A tributary stream that is eroded along an underlying belt of non-resistant rock after the main drainage pattern (consequent river) has been established is known as a subsequent river. Due to the northward slope of the Peninsula towards the Great Plains, the rivers originating from the Vindhyan and the Satpura ranges flow northward into the Ganga system. The Chambal, Sind, Ken, Betwa, Tons, and Son meet the Yamuna and the Ganga at right angles. They are the subsequent drainage of the Ganga drainage system.

• • • Superimposed Epigenetic (Discordant) or Superinduced Drainage: It is formed when a stream with a course originally established on a cover of rock is now removed by erosion so that the stream or drainage system is independent of the newly exposed rocks and structures.

• • • Dendritic Drainage: A term used for drainage which is branching thereby giving the appearance of a tree. Most of the rivers of the Indo-Gangetic Plains are of dendritic type

• • • Trellis Drainage: Trellis is a rectangular pattern formed where two sets of structural controls occur at right angles. In a trellis pattern, the river forms a net-like system and the tributaries flow roughly parallel to each other.

• • • Barbed Pattern: A pattern of drainage in which the confluence of a tributary with the main river is characterized by a discordant junction-as if the tributary intends to flow upstream and not downstream.

• • • Rectangular Drainage: The drainage pattern marked by right-angled bends and right-angled junctions between tributaries and the mainstream is known as rectangular drainage.

• • • Radial Pattern: It is a pattern characterized by outflowing rivers, away from a central point, analogous to the spokes of a wheel. It tends to develop on the flanks of a dome or a volcanic cone.

• • • Annular Pattern: In this drainage pattern, the subsequent streams follow curving or arcuate courses prior to joining the consequent stream.

• • • Parallel Drainage: The drainage pattern in which the rivers flow almost parallel to each other is known as parallel drainage.

• • • Deranged Pattern: This is an uncoordinated pattern of drainage characteristic of a region recently vacated by an ice sheet.

Indian rivers are of two categories: northern rivers and peninsular rivers.

Northern rivers:

Indus:

It has 5 tributaries Chenab, Ravi, Beas, Satluj, and Jhelum. Chenab is the largest. The Indus is one of the most important drainage systems of the subcontinent of India. It has a length of 2880 km, of which 709 km lies in India. The catchment area of the Indus is about 1,165,000 sq km, out of which about 321,284 sq km is in India.

Satluj is the only one that doesn’t originate in India.

Ravi, Beas, Satluj,  Chenab, and Yamuna flow through Himachal Pradesh.

Jhelum (Vitasta): 

1.  Srinagar is on the banks of Jhelum. It is the most important river in Kashmir.
2.  Rises at Verinag

Chenab (Asikni):

1.  Two headward tributaries: Chandra and Bhaga

Ravi (Parushni or Irawati):

1.  Source near Rohtang pass in Himachal Pradesh

Beas (Vipasa or Argikiya):

1.  Source near Rohtang pass in Himachal Pradesh
2.  Entirely within India.

Satluj (Satadru or Satudri):

1.  Originates near Mansarovar.

Fig 1: Indus river system

Ghaggar (the legendary Saraswati)

• • This is inland drainage that rises in the talus fan of the Shiwaliks of Sirrnur near Ambala (Haryana),

• • After entering the plains, it disappears but reappears in Kamal District

• • At present, the entire area is practically a desert, and the Ghaggar-Hakra are practically ephemeral streams coming into flow only during the season of general rains.

Ganga:

    Originates as Bhagirathi from Gangotri. The river is home to more than 140 fish species, 90 amphibian species, and the endangered Ganga river- dolphin.

     Left bank tributaries: Kosi, Ramganga, Gandhak, Gomati, Gaghar.

     Right bank tributaries: Yamuna, Son, Hugli

The Yamuna River(length 1380 km)

• • This is the longest and the westernmost tributary of the Ganga. Its source lies in the Yamunotri Glacier On the western slopes of Banderpunch

• • It joins the Ganga at Allahabad.

• • The important tributaries Of the Yamuna are mostly the right bank tributaries originating from the Aravallis, Vindhyan Range, and the Malwa Plateau of Madhya Pradesh. The Chambal, Sind, Betwa, Ken, and Tons are the main righthand tributaries of the Yamuna River.

The Chambal (length 960 km)

• • The Chambal River is famous for its extensive ravines which it has carved along in the lower Chambal Valley.

Brahmaputra:
Originates in Kailash and enters India as Dibang. Through the Malda gap between Rajmahal and Garo hills passes into the Bay of Bengal. Enters Bangladesh and is known as Jamuna. Meets Ganga and is now called the Padma. Then meets the Meghna river and is called Meghna. Forms a large delta.

Peninsular rivers:

East flowing rivers: Kaveri, Godavari, Krishna, Meghna, Tungabhadra, Mahanadi, Damodar, Suvarna Rekha.

Damodar – source in chota nagpur plateau.

Godawari – dakshin ganga

Krishna – source near Mahabaleshwar.

Mahanadi – Hirakud dam

Rushkiya river – mouth of the river is a hatching site for olive ridley turtles.

Olive ridley turtles- are the most abundant sea turtles in the world. Live in warm waters of the Pacific, Atlantic, and Indian oceans. Odessa coast is the largest mass hatching site for olive ridley turtles.

West flowing river: Narmada and Tapti. These rivers form no delta as they don’t carry any alluvial sediments.

Physiographic Divisions of the Great Plains of India

• • The Great Plains of India are a remarkably homogeneous surface with an imperceptible slope. They are featureless alluvial fertile plains formed mostly by the depositional process of the Himalayan and Vindhyan rivers.

• • The Northern Plains of India may be divided into the following sub-regions:

• • • The Bhabar Plain: It is a highly porous tract of land where small streams disappear into the soil and only large streams survive. This tract isn’t suitable for the survival of crops and thus only big trees grow here that have long roots. The inhabitants of these regions are the cattle herders (Gujjars)

• • • Tarai tract: It is a marshy tract. However, it has been mostly reclaimed for agriculture.

• • • The Bhangar (Bangar) Plains: These are upland alluvial tracts of the Great Plains of India, formed by the older alluviums. The Bhangar land lies above the flood limits of the rivers. The soil is dark in color, rich in humus content, and productive. It contains concretions and nodules of impure calcium carbonate or ‘Kankar’. In relatively drier areas, the Bhangar also exhibits small tracts of saline and alkaline efflorescences known as ‘Reh’, ‘Kallar’, or ‘Thur’. Bhangar is generally a well-drained and the most productive land of the Great Plains of India.

• • • The Khadar Plains: The new alluvium tracts along the courses of the rivers are known as the ‘Khadar’ or ‘Bet lands. The khadar tracts are enriched by fresh deposits of silt every year during the rainy season.

Brahmaputra Plain

• • It is the eastern part of the Great Plains of India. It is a depositional plain, that is surrounded by water from all three sides.

• • The Assam Valley is characterized by a steep slope along its northern margin but the southern side has a gradual fall from the Meghalaya Plateau. The whole length of the plain is traversed by the Brahmaputra. Due to the low gradient, the Brahmaputra is a highly braided river having numerous islands.

• • Majuli (area 930 sq km) is the largest river island of India and the second largest in the world after the Marajo Island of the Amazon River.

The Indian Islands

• • India has a total of 615 islands, of which 572 lie in the Bay of Bengal, and the remaining 43 in the Arabian Sea.

• • The Bay of Bengal islands includes the Andaman and Nicobar Islands which are largely tectonic and volcanic in origin, while the islands of the Arabian Sea are mainly coral formations.

• • One of the largest and also the rarest crabs in the world, the Giant Robber Crab, can be found in the Wandoor Marine Biosphere Reserve in south Andaman and Great Nicobar Islands. Its powerful claws help it to climb the coconut tree and break the hard shell of its fruit.

• • Lakshadweep islands are separated from the Maldive Islands by the Eight Degree Channel.

• • The Andaman Islands have been formed by the extension of the Tertiary mountain chain of Purvachal. The physiography of the Nicobar islands is mainly of coral origin.

RIVER REGIMES

• • The pattern of the seasonal flow of water in a river is called its regime. The main difference in the flow pattern of the Himalayan and the Peninsular rivers is caused by the differences in climate.

• • The Himalayan rivers are perennial and their regimes are dependent on the pattern of water supply both from snow-melt and rainfall. Their regimes are monsoonal as well as glacial.

• • The regime of most of the peninsular rivers, on the other hand, are only monsoonal as they are controlled by rainfall alone.

Major Rivers of Peninsular India

 

River	Source	Length in km	Main tributaries
Godavari	Trimbak Plateau Near Nasik {Maharashtra)	1465	Manjra, Penganga, Wardha Wain ganga, Indravati, Saban, Pranhita
Krishna	Near Mahabaleshwar (Maharashtra)	1400	Koyna, Ghataprabha, Malprabha, Bhima, Tungabhadra, Musi, Muneru
Narmada	Amarkantak	1310	Hiran, Orsang, Barna, Kolar, Burhnar, Tawa, Kundi
Mahanadi	Dandakaranya Plateau near Raipur	857	Ib, Mand, Hasdeo, Seonath, Ong, Jonk, Tel
Kaveri	Taal Kaveri	800	Herangi, Hernavati, Lokpavni, Shimla, Arkavati, Kabani, Bhavani, Amravathi
Tapi	Multai in Betul Dist, (M.P.)	730	Puma, Betul, Patki, Ganjal, Dhatranj, Bokad, Amravati

Comparison of the Peninsular and the Extra-Peninsular Rivers

 

Peninsular	Extra-Peninsular (Himalayan)
The rivers of Peninsular India are much older. Some of them are as old as the Pre-Cambrian Period.	The rivers of Extra-Peninsular India are much younger with few exceptions like Indus, Ganga
They are mostly consequent or rejuvenated rivers.	Inconsequent rivers were mostly
small basins except for Godavari’s	large basins
The channels of these rivers are broad.	The channels of these rivers in the upper courses form gorges, waterfalls, and rapids.
Negligible vertical erosion	Significant vertical, and lateral erosion
Slow-moving, low carrying capacity, mainly depositional agents	Swift movements, transport huge quantities of sediments, active erosional and depositional agents.
Shallow meanders, non-navigable, seasonal nature	Make sharp meanders and oxbow lakes, navigable in plains, perennial nature.
Originate in western ghats	Himalayan origin
Make deltas and estuaries.	These rivers make only deltas. The Sundarban Delta is the largest in the world.