Cauvery

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Hydrological Observation Stations Map

The Cauvery basin extends over states of Tamil Nadu, Karnataka, Kerala and Union Territory of Puducherry draining an area of 81,155 Sq.km which is nearly 2.7% of the total geographical area of the country with a maximum length and width of about 560 km and 245 km. It lies between 75°27’ to 79°54’ east longitudes and 10°9’ to 13°30’ north latitudes. It is bounded by the Western Ghats on the west, by the Eastern Ghats on the east and the south and by the ridges separating it from Krishna basin and Pennar basin on the north. The Cauvery River is one of the major rivers of the peninsula. It rises at an elevation of 1,341 m at Talakaveri on the Brahmagiri range near Cherangala village of Kodagu district of Karnataka. The total length of the river from origin to outfall is 800 km. Its important tributaries joining from left are the Harangi, the Hemavati, the Shimsha and the Arkavati whereas the Lakshmantirtha, the Kabbani, the Suvarnavati, the Bhavani, the Noyil and the Amaravati joins from right. The river drains into the Bay of Bengal. The major part of basin is covered with agricultural land accounting to 66.21% of the total area and 4.09% of the basin is covered by water bodies. The basin spreads over 33 parliamentary constituencies (2009) comprising 18 of Tamil Nadu, 11 of Karnataka, 3 of Kerala and 1 of Puducherry.

The River Cauvery originates at Talakaveri in Coorg District of Karnataka in Brahmagiri Range of hills in the Western ghats at an elevation of 1341 m. (above MSL) and drains a total area of 81,155 Sq.Kms. of which 34,273 Sq.Kms lies in Karnataka, 43856 Sq.Kms. in Tamilnadu , 2866 Sq.Kms. in Kerala and 160 Sq.Kms in Union Territory of Pondicherry. The Cauvery basin is bounded by Tungabhadra sub-basin of Krishna basin on the Northern side and Palar basin on the Southern side.The Western ghats form the Western boundary.The Nilgiris, an offshore of Western ghats, extend Eastwards to the Eastern ghats and divide the basin into two natural and political regions i.e.,Karnataka plateau in the North and the Tamilnadu plateau in the South.In Tamilnadu, the Eastern part of the basin is in the elevation range of 0 to 150 m sloping gently up from the sea.

At Shivanasamudram, the river branches off into two parts and falls through a height of 91 m. in a series of falls and rapids. The falls at this point is utilised for power generation.The power station at Shivanasamudram was built as early as 1902.The two branches of the river join after the fall and flow through a wide gorge which is known as “Mekedatu”(Goats leap) and continues its journey to form the boundary between Karnataka and Tamilnadu States for a distance of 64 Kms.At Hogennekkal Falls, it takes Southernly direction and enters the Mettur Reservoir which was constructed in 1934.A tributary called Bhavani joins Cauvery on the Right bank about 45 Kms below Mettur Reservoir.Thereafter it takes Easternly course to enter the plains of Tamilnadu.Two more tributaries Noyil and Amaravathi join on the right bank and here the river widens with sandy bed and flows as “Akhanda Cauvery”.

Immediately after crossing Tiruchirapalli district, the river divides into two parts, the Northern branch being called “The Coleron” and Southern branch remains as Cauvery and from here the Cauvery Delta begins. After flowing for about 16 Kms, the two branches join again to form “Srirangam Island”. On the Cauvery branch lies the “Grand Anicut” said to have been constructed by a Chola King in 1st Century A.D. Below the Grand Anicut, the Cauvery branch splits into two, Cauvery and Vennar.These branches divide and sub-divide into small branches and form a network all over the delta.

The total length of the river from the origin to its outfall into the sea is 800 Kms. of which 320 Kms.is in Karnataka,416 Kms.in Tamilnadu and 64 Kms. forms the common border between the Karnataka and Tamilnadu states.The Cauvery basin is fan shaped in Karnataka and leaf shaped in Tamilnadu.The run-off does not drain off quickly because of its shape and therefore no fast raising floods occur in the basin.The basin receives rainfall mainly from the S-W Monsoon and partially from N-E Monsoon in the Karnataka. The basin in Tamilnadu receives good flows from the North-East Monsoon.

Cauvery basin extends over an area of 81155 sq.km. which is nearly 2.7% of the total geographical area of the country. It is bounded on the west by the Western Ghats, on the east and south by the eastern Ghats and on the north by the ridges separating it from the Tungabhadra and Pennar basins. The basin lies in the States of Tamil Nadu, Karnataka and Kerala. The State-wise distribution of drainage area is given below

Physiographically, the basin can be divided into three parts – the Westen Ghats, the Plateau of Mysore and the Delta. The delta area is the most fertile tract in the basin. The principal soil types found in the basin are black soils, red soils, laterites, alluvial soils, forest soils and mixed soils. Red soils occupy large areas in the basin. Alluvial soils are found in the delta areas. The culturable area of the basin is about 5.8 M. ha which is about 3% of the culturable area of the country.

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River Overview Map
(Generated Under India WRIS Project)

Cauvery river rises at Talakaveri on the Brahmagiri range in the Western Ghats in Karnataka at an elevation of abut 1341 m and flows for about 800 km before its outfall into the Bay of Bengal.The Cauvery river system consists of 21 principal tributaries each with Catchment Area exceeding 250 Sq.Kms. The largest of all of them are the Catchment Area Shimsha, lying wholly in Karnataka, the Amaravathi rising in Kerala but lying mostly in Tamilandu and the Kabini rising in both Kerala and Tamilnadu but lying mostly in Karnataka. The Bhavani is the fourth largest and the second longest. It rises in Kerala and Karnataka but lies mostly in Tamilnadu. The longest tributary, the Hemavathi (245 Kms.) is the fifth largest in Catchment Area and lies wholly in Karnataka.

From the point of view of flow contribution to the system, apart from the head reach of the Cauvery main, the most important tributaries are i) the Hemavathi, ii) the Kabini and iii) the Bhavani and are briefly described below.

i. The Hemavathi rises in the Western ghats and runs South-East. After a stream from the West joins it, it turns East, receiving the Yagachi from the North. It then winds round Holenarasipur and runs South to the Cauvery near Yedatore.

ii. The Kabini is an important tributary of the Cauvery. it is a perennial river, 150 to 200 M. wide and has a course of about 240 Kms. It rises in the Western ghats in North Wynad in Kerala State as two streams i.e. the Mannantoddypuzha and Panamarampuzha. About 16 Kms. below their confluence, the Kabini forms border between Kerala and Karnataka for about 12 Kms. before entering Karnataka state. It joins the Cauvery at Tirumakudalu Narasipur (T.N.Pur) and this confluence point is being considered as a spot of great sanctity. The confluence point is also called as “Triveni Sangama”.

iii. The Bhavani is a picturesque perennial river of South India, rising in Attappadi valley in Kerala. It enters Tamilnadu near Mannar and traverses from West to East for 170 Kms. and joins the Cauvery near Bhavani Town. It principally receives runoff from the South-West monsoon and occasional floods during North- East Monsoon.

BRIEF REPORT ON DISTRIBUTARIES OF CAUVERY DELTA IN KARAIKAL REGION

There are mainly 7 distributaries from the river Cauvery in delta region that contribute the flow for the Karaikal area which are as follows:

1. Nandalar

2. Nattar

3. Vanjiyar

4. Noolar

5. Arasalar

6. Thirumalairajanar

7. Puravadaiyanar

All the distributaries in the region are non-perennial and flow is mainly due to Cauvery release during June to January. No considerable flow occurs due to South West monsoon. For most of the months in the year, the flows available are the releases/regulated flows from upper regulators maintained by Tamil Nadu. Central Water Commission has set up Hydrological Observation stations on all these distributaries and Gauge & Discharge observations are being taken regularly.

During the pre-plan period many projects were completed in this basin which included Krishnarajasagar in Karnataka, Mettur dam and Cauvery delta system in Tamil Nadu. Lower Bhavani, Hemavati,Harangi, Kabini are important projects completed duing the plan period.

The city of Bangalore is situated just outside this basin. Important industries in the basin include cotton textile industry in Coimbatore and Mysore, cement factories in Coimbatore and Trichinapally and industries based on mineral and metals. The Salem steel plant and many engineering industies in Coimbatore and Trichinapally are also situated in this basin.

Hydrological observation in the basin are carried out by the Central and State Governments. The Central Water Commission maintains 34 gauge-discharge sites in the basin. At 15 of these sites, sediment observations are also taken and water quality is measured at all the stations. In addition, gauge-discharge data are available at 50 sites established by the State Governments concerned.