The river basins under this Organisation are entire Cauvery Basin, the basins South of Krishna River and are as follows:

1. Cauvery Basin
2. Pennar Basin
3. West flowing Rivers below Tadri to Kanyakumari
4. East flowing rivers between Pennar and Kanyakumari

CAUVERY BASIN

Cauvery basin extends over an area of 87,900 sq. km. which is nearly 2.7% of the total geographical area of the country. It is bounded by the Western Ghats on the west, by the Eastern Ghats on the east and south and by the ridges separating it from Krishna basin and Pennar basin on the north. The basin lies in the States Tamil Nadu, Karnataka and Kerala. The State-wise distribution of drainage area is given below:

Physiography

Physiographically, the basin can be divided into three parts—the Western 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 about 3% of the culturable area of the country.

River System

Cauvery River rises at Talakaveri on the Brahmagiri range in the Western Ghats in Karnataka at elevation of about 1341 m and flows for about 800 km before its outfall into the Bay of Bengal. The important tributaries joining the Cauvery are Harangi, Hemavati, Kabini, Suvarnavathi and Bhavani.

Hydropower Development

Recent hydropower potential survey in the basin has identified 30 hydropower projects with a total potential of 1359 MW at 60% load factor.

PENNAR BASIN

Physiography

Pennar basin extends over an area of 55,213 sq. km. which is nearly 1.7% of the total geographical area of the country. It is bounded on the north by the Erramala range, on the east by Nallamala and Velikonda ranges of the Eastern Ghats, on the south by Nandidurg hills and on the west by the narrow ridge separating it from the Vedavati valley of the Krishna basin. The basin lies in the States of Andhra Pradesh and Karnataka. The State-wise distribution of drainage area is given below:

The important soil types found in the basin are red soils, black soil, sandy soil and mixed soil. The cultivable area of the basin is about 3.54 M.ha which is about 1.8% of the total cultivable area of the country.

River System

Pennar river rises from the Chenna Kesava hills of the Nandi ranges of Karnataka and flows for about 597 km before outfalling into Bay of Bengal. The principal tributaries of the river are Jayamangal, Kunderu, Sagileru, Chitravati, Papagni and Cheyyeru.

Hydropower Development

The basin does not have scope for hydropower development.

WEST FLOWING RIVERS BELOW TADRI TO KANNIYAKUMARI

Physiography

The basin extends over states of Kerala, Karnataka, Tamil Nadu and Union Territory of Puducherry having an area of 54,825 Sq. km, which is 1.66% of total geographical area of the country. The basin is bounded by Sahyadri hills on the north, by the Western Ghats on the east, by Indian Ocean on the south and by the Arabian Sea on the west. The basin is comprised of three sub-basins; Netravati and associated sub basin, Periyar and associated sub basin and Varrar and associated sub basin. The State-wise distribution of drainage area is given below:

River System

The major independent rivers in the basin are Varahi, Netravati, Payaswani, Valapattanam, Chaliyar, Kadalundi, Bharathapuzha, Periyar, Muvattupula, Minachil, Pamba, Achankovil, Kallada and Vamanapuram.

Hydropower Development

Recent hydropower potential survey in the basin has identified 29 hydropower projects with a total potential of 4450 MW.

EAST FLOWING RIVERS BETWEEN PENNAR AND KANYAKUMARI

Physiography

The basin extends over states of Tamil Nadu, Andhra Pradesh, Karnataka and Union Territory of Puducherry having a total area of 1,02,409 sq. km. It is bounded by the Eastern Ghats on the north, by Tamil Nadu uplands on the west, by the Indian Ocean on the south and by the Bay of Bengal on the east. The basin extends between 77°1’ to 80°17’ east longitudes and 8°11’ to 14°27’ north latitudes. The State-wise distribution of drainage area is given below:

River System

The composite basin comprises of the river systems between Pennar and Cauvery having an area of 63,646.2 Sq.km and the river systems between Cauvery and Kanyakumari with an area of 38,646.1 Sq.km. The independent rivers (directly draining into Bay of Bengal) are Kandleru, Swarnamukhi, Arani, Korttalaiyar, Cooum, Adyar, Palar, Gingee, Ponnaiyar, Vellar, Varshalei, Vaigai, Gundar, Vaippar and Tambraparni. The basin is comprised of four sub-basins; Vaippar and associated Sub-basin, Palar and associated sub-basin, Pamba and associated sub-basin and Ponnaiyar and associated sub-basin.

Hydropower Development

Recent hydropower potential survey in the basin has identified 6 hydropower projects with a total potential of 236.5 MW.