Major Rivers of Bihar

Major Rivers of Bihar

 

 

1. Introduction

Bihar, located in eastern India, is one of the most river-rich states in the country. The rivers of Bihar have shaped its civilisation, agriculture, economy, and culture for thousands of years. Bihar is bounded by the Ganga (Ganges) river and its numerous tributaries, making it an agriculturally fertile but flood-prone region. The rivers originate mainly from the Himalayan ranges in Nepal and the Chota Nagpur Plateau.

The state can be broadly divided into:

• North Bihar – drained by rivers from Nepal's Himalayas (Gandak, Kosi, Bagmati, Kamla, Burhi Gandak, Mahananda)
• South Bihar – drained by rivers from the Chota Nagpur Plateau (Son, Punpun, Falgu, Sakri)
• The Ganga flows through the middle of Bihar, acting as the main trunk river

 

2. Quick Reference: Major Rivers at a Glance

River	Origin	Length (Approx.)	Tributary of	Characteristics
Ganga (Ganges)	Gangotri Glacier, Uttarakhand	~2,525 km (total)	Bay of Bengal	Main river; holiest river
Son	Amarkantak, MP	~784 km	Ganga (right bank)	Largest South Bihar river
Gandak (Narayani)	Nepal Himalayas	~630 km	Ganga (left bank)	Boundary river with UP
Kosi	Tibet/Nepal Himalayas	~720 km	Ganga (left bank)	Sorrow of Bihar; floods
Bagmati	Kathmandu Valley, Nepal	~597 km	Kosi / Ganga	Flash floods in monsoon
Burhi Gandak	Sомаrpur Hills, Nepal	~320 km	Ganga (left bank)	Flows through Muzaffarpur
Mahananda	Darjeeling Hills	~360 km	Ganga (left bank)	Easternmost river of Bihar
Kamla-Balan	Nepal Himalayas	~328 km	Kosi / Bagmati	Madhubani district floods
Punpun	Palamu plateau, Jharkhand	~200 km	Ganga (right bank)	Flows through Patna region
Falgu	Chota Nagpur Plateau	~238 km	Ganga	Underground flow in dry season

 

3. The Ganga (Ganges)

Origin and Course

The Ganga originates from the Gangotri Glacier in Uttarakhand. It enters Bihar at Chausa (Buxar district) and exits at Manihari (Katihar district) near the Bihar–West Bengal border. It flows for approximately 445 km within Bihar.

 

Key Features

• Divides Bihar into North Bihar and South Bihar
• Receives major tributaries: Son, Punpun (right bank); Gandak, Sone, Kosi, Bagmati, Burhi Gandak, Mahananda (left bank)
• The holy city of Patna (Pataliputra) lies on its southern bank
• Hajipur, Chhapra, Bhagalpur, Munger are important towns along its banks
• Forms the Vikramshila Gangetic Dolphin Sanctuary in Bhagalpur – a protected zone for the endangered Gangetic river dolphin

 

Significance

• Religious: considered the holiest river in Hinduism; Sonepur Mela (largest cattle fair in Asia) is held at Ganga–Gandak confluence
• Agricultural: provides irrigation to millions of hectares
• Historical: ancient cities of Pataliputra, Vaishali flourished on its banks
• Transport: historically used for trade and navigation

 

4. Son River

Origin and Course

The Son (Sone) originates near Amarkantak in Madhya Pradesh, at the same location as the Narmada and Johilla rivers. It flows through Jharkhand before entering Bihar near Dehri-on-Sone (Rohtas district) and meets the Ganga near Arrah / Patna region.

 

Key Features

• Longest river originating from South Bihar's plateau region; total length ~784 km
• Known for its sandy riverbed and golden-colored sand (hence the name 'Son' meaning gold)
• Flows through Rohtas, Aurangabad, Arwal districts
• The Indrapuri Barrage and Dehri Barrage are important irrigation structures on this river
• Tributaries in Bihar: North Koel, Rihand, Kanhar

 

Economic Importance

• Major source of sand for construction in Bihar
• Irrigation canals from Son River irrigate Arwal, Jahanabad, Patna, Bhojpur districts
• Hydroelectric potential at Dehri-on-Sone

 

5. Gandak (Narayani)

Origin and Course

The Gandak originates in the Nepal Himalayas and is known as Narayani in Nepal. It enters Bihar at Trivenighat (West Champaran) and meets the Ganga at Hajipur/Sonpur (Vaishali district). The total length in Bihar is about 300 km.

 

Key Features

• Acts as the boundary between Bihar and Uttar Pradesh
• The Gandak Project (Valmikinagar Barrage) is a major multipurpose project for irrigation and flood control.
• The Sonepur Mela (Kartik Purnima fair) is held at the Gandak–Ganga confluence.
• It passes through West Champaran, East Champaran, Muzaffarpur, Vaishali districts.
• Carries huge silt load causing frequent course changes

 

6. Kosi River – 'The Sorrow of Bihar'

Origin and Course

The Kosi originates in Tibet near Mount Everest as the Sun Kosi. It is joined by the Arun and Tamur rivers in Nepal to form the Saptakoshi (Seven Kosi). It enters Bihar through Supaul district and meets the Ganga near Kursela (Katihar district).

 

Why Called 'Sorrow of Bihar'?

• The Kosi has shifted its course over 120 km westward in the past 250 years – one of the highest lateral migration rates of any river globally
• Causes devastating floods almost every year, affecting Supaul, Saharsa, Madhepura, Khagaria districts
• The 2008 Kosi flood was catastrophic – the river breached the eastern embankment near Kusaha (Nepal), displaced millions and inundated 3,000+ villages
• Brings enormous silt load, raising the riverbed and causing the river to spill over banks

 

Flood Control Measures

• Kosi High Dam (Barahkshetra, Nepal) – proposed but not yet built
• Eastern and Western Kosi Embankments along its course
• Birpur Barrage / Hanuman Nagar Barrage (in Nepal) – regulates water flow
• National Flood Management Programme investments in embankments

 

7. Bagmati River

Origin and Course

The Bagmati originates near Kathmandu, Nepal (Shivapuri Hills) and is a sacred river for both Hindu and Buddhist communities. It enters Bihar in Sitamarhi district and merges with the Kosi/Budhi Gandak system before joining the Ganga.

 

Key Features

• Known as 'the Kosi of Mithila' due to its flooding pattern in Sitamarhi, Sheohar, Darbhanga, Muzaffarpur districts
• Course changes frequently due to high silt deposition
• The Bagmati Project (Runni Saidpur Barrage) was constructed for irrigation and flood management.
• Religiously important in Bihar's Mithila culture

 

8. Burhi Gandak

Burhi Gandak (Old Gandak) originates in the Sомаrpur Hills of the Someshwar range near the Nepal border in West Champaran. It flows through Muzaffarpur and Vaishali districts before joining the Ganga near Munger.

• Total length: ~320 km in Bihar
• Causes periodic floods in Muzaffarpur, Samastipur, Begusarai, Khagaria and Munger districts
• Receives tributaries: Sikrahna, Pandai, Dhanauti
• Har Simaria Barrage constructed to manage water flow

 

9. Mahananda River

The Mahananda originates in the Darjeeling Hills (West Bengal). It flows through Kishanganj and Purnia districts of Bihar and ultimately drains into the Ganga in West Bengal. It forms the easternmost drainage system of Bihar.

• Passes through Kishanganj (Bangladesh border area)
• Tributaries in Bihar: Mechi, Kankai, Kali, Donk
• Prone to severe floods, especially in Kishanganj and Araria districts
• The Mahananda River is important ecologically as it supports a variety of fish species and wetland habitats.

 

10. Punpun and Falgu Rivers

Punpun River

Punpun originates in the Palamu plateau of Jharkhand. It flows through Aurangabad, Gaya, Arwal, Patna, and Nalanda districts before joining the Ganga near Fatuha (Patna district). Length ~200 km.

• Major right-bank tributary of the Ganga in Bihar
• Historically important: flows near ancient city of Pataliputra
• Tributaries: Morhar, Dardha, Jabra

 

Falgu River

Falgu is a sacred river for Hindus and Jains. It is formed by the confluence of the Niranjana (Lilajan) and Mohane rivers at Bodhgaya, Gaya. It joins the Phalgu which eventually reaches the Ganga.

• Famous for the Pind Daan rituals performed by Hindus at Vishnupad temple in Gaya
• Often dry or underground during non-monsoon months – called a 'mythological river with cursed flow'
• Legend: Sita cursed the Falgu river, which is why it flows underground

 

11. North Bihar Rivers vs South Bihar Rivers

Feature	North Bihar Rivers	South Bihar Rivers
Origin	Himalayan ranges / Nepal	Chota Nagpur Plateau / Central India
Nature	Perennial (year-round flow)	Seasonal / rainfed
Flood Frequency	Very high – annual floods	Moderate – flash floods
Silt Load	Very high – fertile alluvial deposits	Lower – coarser material
Examples	Gandak, Kosi, Bagmati, Burhi Gandak, Mahananda	Son, Punpun, Falgu
Agriculture	Kharif crops; fertile flood plains	Rabi crops; irrigated farming
Key Issues	Embankment breaches, displacement	Low water availability in dry season

 

12. Flood Management in Bihar

Bihar has 28% of India's total flood-prone area, making flood management a critical issue. Key strategies include:

• Construction and maintenance of embankments along major rivers
• Barrages and dams: Gandak Barrage (Valmikinagar), Kosi Barrage (Birpur), Son Barrage (Dehri), Bagmati Barrage (Runni Saidpur)
• River linking proposals: Kosi–Mechi, Kosi–Ganga link
• Bihar Flood Management Improvement Support Project (World Bank funded)
• Early warning systems and flood forecasting centres
• The 2004 and 2008 Kosi floods led to major policy reforms

 

13. Economic and Cultural Significance

Agriculture

• Rivers support irrigation for rice, wheat, maize, sugarcane and vegetables
• Son Canal System irrigates ~3 lakh hectares in South Bihar
• Gandak Canal and Kosi Canal systems serve North Bihar

 

Fisheries

• Major source of livelihood for riparian communities
• The Ganga near Bhagalpur supports the Gangetic dolphin sanctuary

 

Religion and Culture

• Ganga – Sonepur Mela, Chhath Puja (celebrated on the banks of all rivers)
• Falgu (Gaya) – most important Hindu pilgrimage site for ancestor rites (Pitru Paksha Mela)
• Kosi – worshipped as a goddess in Mithila folk traditions

 

Transport and Trade

• Historical: Pataliputra was a major port city on the Ganga
• National Waterway 1 (NW-1): Allahabad–Haldia via Patna passes through Bihar