PENINSULAR RIVER SYSTEM: SOME BASICS

• Peninsula rivers are much older than the Himalayan rivers {Discordant}.
• The peninsular drainage is mainly Concordant except for few rivers in the upper peninsular region. They are non-perennial rivers with a maximum discharge in the rainy season.
• The peninsular rivers have reached mature stage {Fluvial Landforms} and have almost reached their base [Vertical down cutting is negligible] which are characterized by broad and shallow valleys.
• The river banks have gentle slopes except for a limited tract where faulting forms steep sides.
• The main water divide in peninsular rivers is formed by the Western Ghats, which run from north to south close to the western coast.
• The velocity of water in the rivers and the load carrying capacity of the streams is low due to low gradient.
• Most of the major rivers of the peninsula such as the Mahanadi, the Godavari, the Krishna and the Cauvery flow eastwards and drain into the Bay of Bengal. These rivers make deltas at their mouths.
• But the west flowing rivers of Narmada and Tapi as well as those originating from the Western Ghats and falling in the Arabian Sea form estuaries in place of deltas.
• There are few places where rivers form superimposed and rejuvenated drainage which are represented by Examples: The Jog on the Sharvati (289 m), Yenna of Mahabaleshwar (183 m), Sivasamundram on the
• Cauvery (101 m), Gokak on the Gokak (55 m), Kapildhara (23 m) and Dhuandar (15 m) on the Narmada are the major waterfalls in the Peninsular India.
• Rivers that drain into Bay of Bengal: The Mahanadi, the Godavari, the Krishna, the Cauvery and several smaller rivers drains south-east into the Bay of Bengal.
• Rivers that drain into Arabian Sea: The Narmada, the Tapi, the Mahi flowing west as well as several small streams originating from the Western Ghats flow westwards into the Arabian Sea.
• Rivers that drain into the Ganges: Tributaries of the Ganga and the Yamuna such as the Chambal, the Betwa, the Ken, the Son and the Damodar flow in the north-easterly direction.

Rivers that drain into the Ganges

1. Chambal River
2. Banas River
3. Sind River
4. Betwa River
5. Ken River
6. Son River
7. Damodar River

East Flowing Peninsular Rivers

1. Mahanadi River
2. Godavari River
3. Krishna River
4. Kaveri (Cauvery) River
5. Pennar River
6. Subarnarekha River
7. Brahamani River
8. Sarada River
9. Ponnaiyar River
10. Vaigai River

West Flowing Peninsular Rivers

1. Narmada River
2. Tapti River
3. Sabarmati River
4. Mahi River
5. Luni River
6. Ghaggar River – Inland Drainage

 

Evolution of the Peninsular Drainage

Theory 1 

• Geologists believe that the Sahyadri Aravali axis was the main water divide in¢ the past.
• According to one hypothesis, the existing¢ peninsula is the remaining half of bigger landmass.
• The Western Ghats were located in the¢ middle of this landmass.
• So Kone drainage was towards east flowing¢ into Bay of Bengal and the other towards west draining into Arabian Sea.
• The western part of the Peninsula cracked¢ and submerged in the Arabian Sea during the early Tertiary period (coinciding with the formation of Himalayas).
• During the collision of the Indian plate, the¢ Peninsular block was subjected to subsidence in few regions creating a series of rifts (trough, faults).
• The now west flowing rivers of the¢ Peninsula, namely the Narmada and the Tapi flow through these rifts.
• Straight coastline, steep western slope of the¢ Western Ghats, and the absence of delta formations on the western coast makes this theory a possibility.

Theory2 

• It is believed that the west flowing peninsular¢ rivers do not flow in the valleys formed by the rivers themselves.
• Rather they have occupied two fault rifts in¢ rocks running parallel to the Vindhyas.
• These faults are supposed to be caused by¢ bend of the northern part of the Peninsula at the time of upheaval of the Himalayas.
• Peninsular block, south of the cracks, tilted¢ slightly eastwards during the event thus giving the orientation to the entire drainage towards the Bay of Bengal.
• Criticism: Tilting should have increased the¢ gradient of the river valleys and caused some rejuvenation of the rivers. This type of phenomenon is absent in the Peninsula, barring a few exceptions such as waterfalls.

Comparison Chart

BASIS FOR COMPARISON	HIMALAYAN RIVERS	PENINSULAR RIVERS
Meaning	Himalayan Rivers are the rivers that originate from Himalayan ranges and flows throughout the year.	Peninsular Rivers include those rivers that arises from Western Ghats and receive water only during a particular period.
Nature	Perennial	Non-perennial
Form	Delta	Some rivers form delta while others form Estuary
Shape	Meandering	Straight
Rocks	Bed rocks are soft, sedimentary and easily erodible	Bed rocks are hard, resistant and not easily erodible
Fed by	Snow and rain	Rain
Drainage basin	Large	Small
Irrigate	Northern Plains	Deccan Plateau
Valley	V-shaped valley is formed	U-shaped valley is formed