Drainage and Drainage System

DRAINAGE AND DRAINAGE SYSTEM

**Drainage** is the flow of water through well-defined channels. **Drainage system** is the network of channels through which water flows. Drainage is essential to prevent flooding. The **drainage pattern** of an area is determined by: geological time period, nature and structure of rocks, topography, slope, amount of water flowing, and periodicity of flow.

**Catchment area** is the specific area from which a river collects water. **Drainage basin** is the area drained by a river and its tributaries. **Watershed** is the boundary line separating one drainage basin from another. **River basin** refers to larger catchments while **watershed** refers to smaller ones, though both mark areas of unity where changes in one part affect the whole unit.

River basins and watersheds serve as the most appropriate micro, meso, and macro planning regions because they function as unified systems.

IMPORTANT DRAINAGE PATTERNS

**Dendritic Pattern**: Branches resemble a tree. The river system consists of a main channel with tributaries joining at acute angles. Example: Rivers of the northern plains like those in the Ganga basin.

**Radial Pattern**: Rivers originate from a hill or highland and flow in all directions. Example: Rivers originating from the Amarkantak range flowing in multiple directions.

**Trellis Pattern**: Primary tributaries flow parallel to each other while secondary tributaries join them at right angles. This pattern develops in fold mountains with alternating ridges and valleys.

**Centripetal Pattern**: Rivers discharge water from all directions into a lake or depression. Water flows toward a central point rather than toward the sea.

CLASSIFICATION OF INDIAN DRAINAGE

**On the Basis of Discharge Orientation**:

**Arabian Sea drainage**: 23% of drainage area including Indus, Narmada, Tapi, Mahi, and Periyar river systems

**Bay of Bengal drainage**: 77% of drainage area including Ganga, Brahmaputra, Mahanadi, Krishna systems

Water divide separations: Delhi Ridge, Aravallis, and Sahyadris separate these two major drainage systems.

**On the Basis of Catchment Area Size**:

**Major river basins**: Catchment area > 20,000 sq. km (14 basins: Ganga, Brahmaputra, Krishna, Tapi, Narmada, Mahi, Pennar, Sabarmati, Barak, etc.)

**Medium river basins**: Catchment area 2,000-20,000 sq. km (44 basins: Kalindi, Periyar, Meghna, etc.)

**Minor river basins**: Catchment area < 2,000 sq. km (numerous rivers in low rainfall areas)

**On the Basis of Origin and Characteristics**:

**Himalayan drainage**: Fed by snowmelt and precipitation, perennial rivers

**Peninsular drainage**: Older system, mature rivers with graded valleys

Most accepted classification uses Himalayan vs. Peninsular drainage despite including some older rivers (Chambal, Betwa, Son) in the Himalayan group.

HIMALAYAN DRAINAGE CHARACTERISTICS

Himalayan rivers possess distinctive features:

**Perennial nature**: Flow throughout the year due to snowmelt and precipitation

**Deep gorges and V-shaped valleys**: Formed by erosional activity concurrent with Himalayan uplift

**Depositional features in plains**: Flat valleys, ox-bow lakes, flood plains, braided channels, deltas

**Tortuous mountain course**: Highly winding path in Himalayan reaches

**Meandering tendency**: Strong meandering pattern over plains with frequent course shifts

**River Kosi**: Known as the "sorrow of Bihar" due to notorious course changes caused by massive sediment deposits blocking the channel. Its upper reaches bring enormous quantities of sediments that obstruct flow, forcing the river to abandon its course.

EVOLUTION OF HIMALAYAN DRAINAGE

**Shiwalik or Indo-Brahma River Theory**: Geologists believe a mighty river called Shiwalik (or Indo-Brahma) traversed the entire longitudinal extent of the Himalaya from Assam to Punjab and Sind during the **Miocene period** (5-24 million years ago), discharging into the Gulf of Sind. Evidence includes:

Remarkable continuity of Shiwalik deposits

Lacustrine origin (lake-formed)

Alluvial deposits of sands, silt, clay, boulders, conglomerates

**Dismemberment into Three Systems**: The Indo-Brahma river was broken into three during Pleistocene upheavals:

**Indus system**: Western part with five tributaries

**Ganga system**: Central part with Himalayan tributaries

**Brahmaputra system**: Eastern part (Assam and Himalayan tributaries)

**Causes of Dismemberment**:

Pleistocene upheaval in western Himalayas including Potwar Plateau (Delhi Ridge) uplift acted as water divide between Indus and Ganga

Down-thrusting of Malda gap area (between Rajmahal hills and Meghalaya plateau) in mid-Pleistocene diverted Ganga and Brahmaputra toward Bay of Bengal

THE INDUS RIVER SYSTEM

**Specifications**:

One of world's largest river basins: 11,65,000 sq. km total (321,289 sq. km in India)

Total length: 2,880 km (1,114 km in India)

Also known as Sindhu (westernmost Himalayan river in India)

**Origin and Course**:

Originates from glacier near Bokhar Chu (31°15'N, 81°40'E) at 4,164 m altitude in Kailash Mountain range, Tibet

Known as "Singi Khamban" (Lion's mouth) in Tibet

Flows northwest between Ladakh and Zaskar ranges

Cuts spectacular gorge near Gilgit in Ladakh

Forms antecedent river crossing the Ladakh range

Enters Pakistan near Chilas in Dardistan region

**Himalayan Tributaries in India**:

Shyok, Gilgit, Zaskar, Hunza, Nubra, Shigar, Gasting, Dras

**Important Tributaries Joining Near Attock**:

Kabul river (right bank)

Khurram, Tochi, Gomal, Viboa, Sangar (right bank; originate in Sulaiman ranges)

**Panjnad Confluence**: Receives Panjnad above Mithankot, which comprises five Punjab rivers: **Satluj, Beas, Ravi, Chenab, and Jhelum**

**Final Discharge**: Flows southward and discharges into Arabian Sea east of Karachi

**States in India**: Flows through Union Territories of Ladakh and Jammu & Kashmir

INDUS TRIBUTARIES

**Jhelum**:

Rises from Verinag spring at Pir Panjal foot in Kashmir valley (southeastern part)

Flows through Srinagar and Wular lake

Enters Pakistan through deep narrow gorge

Joins Chenab near Jhang in Pakistan

**Chenab**:

Largest tributary of Indus

Formed by Chandra and Bhaga streams joining at Tandi near Keylong, Himachal Pradesh

Also known as Chandrabhaga

Length: 1,180 km before entering Pakistan

**Ravi**:

Rises west of Rohtang Pass in Kullu hills, Himachal Pradesh

Flows through Chamba valley

Drains area between southeastern Pir Panjal and Dhauladhar ranges

Joins Chenab near Sarai Sidhu in Pakistan

**Beas**:

Originates from Beas Kund near Rohtang Pass at 4,000 m elevation

Flows through Kullu valley

Forms gorges at Kati and Largi in Dhauladhar range

Meets Satluj near Harike in Punjab plains

**Satluj**:

Originates in Raksas tal near Mansarovar at 4,555 m altitude in Tibet

Known as Langchen Khambab in Tibet

Flows parallel to Indus for ~400 km before entering India

**Antecedent river**: Cuts through rising mountains maintaining original course

Emerges from gorge at Rupar, passes through Shipki La

Important for Bhakra Nangal multipurpose project canal systems

THE GANGA RIVER SYSTEM

**Specifications and Significance**:

Most important river of India (basin and cultural significance)

Length: 2,525 km

Basin area: 8.6 lakh sq. km in India alone

Largest river system in India with perennial and non-perennial tributaries

Shared by: Uttarakhand (110 km), Uttar Pradesh (1,450 km), Bihar (445 km), West Bengal (520 km)

**Origin and Upper Course**:

Rises in Gangotri glacier near Gaumukh (3,900 m) in Uttarkashi district, Uttarakhand

Initially called Bhagirathi

Cuts through Central and Lesser Himalayas in narrow gorges

**Alaknanda Confluence at Devprayag**:

Bhagirathi meets Alaknanda at Devprayag

After this confluence, called Ganga

Alaknanda source: Satopanth glacier above Badrinath

Alaknanda tributaries: Dhauli and Vishnu Ganga meet at Joshimath (Vishnu Prayag)

Alaknanda other tributaries: Pindar joins at Karna Prayag; Mandakini (Kali Ganga) at Rudra Prayag

**Entry to Plains**:

Enters plains at Haridwar

Flows south, then southeast and east

Splits into two distributaries: **Bhagirathi and Padma**

Finally discharges into Bay of Bengal near Sagar Island

**Major Right Bank Tributary**:

**Son**: Large tributary originating in Amarkantak plateau, forming series of waterfalls, joining near Arrah west of Patna

**Important Left Bank Tributaries**:

Ramganga, Gomati, Ghaghara, Gandak, Kosi, Mahananda

YAMUNA RIVER (GANGA TRIBUTARY)

**Specifications**:

Westernmost and longest tributary of Ganga

Source: Yamunotri glacier on western slopes of Banderpunch range (6,316 m)

Joins Ganga at Prayag (Allahabad)

**Right Bank Tributaries** (from Peninsular plateau):

Chambal, Sind, Betwa, Ken

**Left Bank Tributaries**:

Hindan, Rind, Sengar, Varuna

**Water Utilization**: Much water feeds western and eastern Yamuna canals and Agra canal for irrigation

CHAMBAL RIVER

Rises near Mhow in Malwa plateau, Madhya Pradesh

Flows northward through gorge up to Kota, Rajasthan

Gandhisagar dam constructed at Kota

Traverses through Bundi, Sawai Madhopur, Dholpur before joining Yamuna

**Famous for**: Chambal ravines (badland topography)

OTHER GANGA TRIBUTARIES

**Gandak**:

Comprises Kaligandak and Trishulganga streams

Rises in Nepal Himalayas between Dhaulagiri and Mount Everest

Drains central Nepal

Enters Ganga plain in Champaran district, Bihar

Joins Ganga at Sonpur near Patna

**Ghaghara**:

Originates in glaciers of Mapchachungo

Collects waters of tributaries: Tila, Seti, Beri

Cuts deep gorge at Shishapani

Sarda (Kali or Kali Ganga) joins in plain

Meets Ganga at Chhapra

**Kosi**:

**Antecedent river**: Source north of Mount Everest in Tibet (main stream Arun)

Crosses Central Himalayas in Nepal

Joined by Son Kosi (west) and Tamur Kosi (east)

Forms **Sapt Kosi** after uniting with Arun river

Notable for frequent course changes and silt load

**Ramganga**:

Small river rising in Garhwal hills near Gairsain

Changes course southwest after crossing Shiwalik

Enters Uttar Pradesh plains near Najibabad

Joins Ganga near Kannauj

**Damodar**:

Occupies eastern margins of Chotanagpur Plateau

Flows through rift valley

Joins Hugli river

Main tributary: Barakar

Once called "sorrow of Bengal"; now controlled by Damodar Valley Corporation multipurpose project

**Sarda/Saryu**:

Rises in Milam glacier, Nepal Himalayas (called Goriganga there)

Called Kali or Chauk along Indo-Nepal border

Joins Ghaghara

**Mahananda**:

Rises in Darjiling hills

Last left bank tributary of Ganga in West Bengal

THE BRAHMAPUTRA RIVER SYSTEM

**Specifications**:

One of world's largest rivers

Origin: Chemayungdung glacier of Kailash range near Mansarovar lake

Traverses eastward for ~1,200 km in southern Tibet

Known as **Tsangpo** in Tibet (means "the purifier")

**Tibetan Course**:

Flows eastward in dry, flat southern Tibet region

Major right bank tributary in Tibet: Rango Tsangpo

**Emergence and Entry to India**:

Becomes turbulent after carving deep gorge in Central Himalayas near Namcha Barwa (7,755 m)

Emerges as Siang or Dihang

Enters India west of Sadiya town, Arunachal Pradesh

**Journey Through Assam Valley**:

Flows southwest receiving left bank tributaries: **Dibang (Sikang) and Lohit**

After receiving these tributaries, called Brahmaputra

750 km journey through Assam valley

Receives numerous tributaries along Assam route

**Major Left Bank Tributaries in Assam**:

Burhi Dihing, Dhansari (South)

**Important Right Bank Tributaries**:

Subansiri (antecedent river with origin in Tibet), Kameng, Manas, Sankosh

**Final Course**:

Enters Bangladesh near Dhubri, flows southward

Tista joins from right bank in Bangladesh

Known as Jamuna after Tista confluence

Merges with Padma river

Falls into Bay of Bengal

**Characteristics**:

Well-known for floods, channel shifting, bank erosion

Large tributaries bring massive sediment quantities

Heavy rainfall in catchment area causes seasonal flooding

PENINSULAR DRAINAGE SYSTEM

**Age and Characteristics**:

Older than Himalayan drainage system

Evident from broad, largely-graded shallow valleys and river maturity

Fixed river courses, absence of meanders (except Narmada and Tapi)

Non-perennial flow of water in most rivers

**Water Divide**: **Western Ghats** running close to western coast act as main watershed separating:

Major rivers flowing west to east toward Bay of Bengal

Small rivulets flowing toward Arabian Sea

**Flow Direction**: Most major Peninsular rivers (except Narmada and Tapi) flow **west to east**

**Peninsular Rivers in Ganga System**:

Originating in northern Peninsula: Chambal, Sind, Betwa, Ken, Son

**Major Peninsular River Systems**:

Mahanadi, Godavari, Krishna, Kaveri (flowing to Bay of Bengal)

Narmada, Tapi (flowing to Arabian Sea)

**Exception Rivers**: Narmada and Tapi flow through rift valleys and are exceptions to typical peninsular characteristics, resembling Himalayan rivers in some respects

EVOLUTION OF PENINSULAR DRAINAGE SYSTEM

**Three Major Geological Events**:

**1. Subsidence of Western Flank** (Early Tertiary Period):

Western flank of Peninsula submerged below sea

Disturbed symmetrical river plan on either side of original watershed

Rivers adjusted drainage patterns to new base levels

**2. Upheaval of Himalayas**:

Diverted rivers from original northwest-southeast orientation

Forced major rivers to flow toward Bay of Bengal instead of westward

Caused extensive drainage reorganization

**3. Subsequent Geological Events** (implied structure):

Created present drainage configuration

Established fixed courses and mature valley systems

Determined river characteristics and flow patterns

The Peninsular drainage represents an older, more stabilized system shaped by millions of years of geological adjustment, contrasting with the younger, more dynamic Himalayan drainage system.