THE CAUVERY DELTA
Delta ID # 49.
Drainage basin: Peninsular India.
Depositional basin: Bay of Bengal.
Climate: Per humid.
Air temperature range: oC to oC
Mean wave height:
Drainage Basin area:
Contributed by Professor George F. Hart, LSU. Hart, 1999.
Photographic album of Cauvery Delta slides.
The climate is dominated by the monsoonal rains. The northeast monsoon provides the greater portion of the annual precipitation. The far northwestern part of the drainage basin has a Perhumid climate which passes eastwards into humid, moist subhumid, dry subhumid and semiarid zones.
The geology of the drainage basin is predominantly formed from Precambrian rocks, principally the Dharwars, Peninsular granitic Gneiss, Charnockites and the Closepet Granite [Krishnan, 1968]. The Dhawar metamorphics comprising phyllites, slates, schists with chlorite, biotite, garnet, staurolite, kyanite, silllimanite and hornblende. Accompanying these are greenstones and quartzite [Rama Rao, 1940; Srinivasan & Sreenivas, 1977; Krishnan, 1968; Naqvi et al., 1974]. The Closepet Granite of the upper reaches of the drainage basin is a pink granite consisting mainly of quartz, plagioclase, microcline, perthite, and subordinate hornblende, biotite, rutile, apatite, zircon and occasional fluorite [Radhakrishna, 1956; Chatterji, 1974].Over the main part of the basin the Peninsular granites and gneisses comprise biotite granitic gneiss, hornblende granitic gneiss adamellite, granodiorite, diorite, and pegmatite [Chatterji, 1974; Pichamuthu, 1978]. The Charnockites are confined to the Nilgiri Range in the central part of the drainage basin. The are represented by gabbros, olivine norites, pyroxene - hypersthene granulites [Pichamuthu, 1953; Viswanathiah & Tareon, 1970; Chatterji, 1974]. Cretaceous sediments crop out in the coastal region and consists of conglomeratic sandstone, coralline limestone and shale [Rao & Sundaraw, 1978].
The Cauvery [Kaveri] River is one of the sacred rivers of India and from it's origin in the Brahmagiri Hills, of the Coorg region in Karnataka State, to it's entrance into the Bay of Bengal, south of Cuddalore, Tamil Nadu, it is steeped in Dravidian history. Although the upper reaches have continuous annual flow the mid and lower sections are damned and bled for irrigation water. The Shivasamudram Falls which are the second largest waterfalls in India are on the Cauvery River. These are dual rapids with a 100 meters drop and some 300 meters wide as maximum flood stage: Bhar Chukki and Gagana Chukki. Hydroelectricity is produced by these falls for consumption in Mysore and Bangalore. In addition, the picturesque Hogenakal Falls, lie on the border between Karnataka and Tamil Nadu. Below the falls, near the town of Salem, the 155 sq km Stanley Reservoir is impounded by the 154 meter high Mettur Dam.
Geologically the Cauvery River is influenced by a major structural depression in the southern part of the Dharwar Dome Granulite Belt. The Cauvery River drainage basin originates in the Brahmagiri Range of the Western Ghats, Karnataka at an elevation of some 1,340 m [Rao, 1975]. Geologically this is within the Dharwar [Karnataka] Craton, which is a Granite-Gneiss-Greenbelt massif. It is a small river some ~765 km. [475 miles] long and has a drainage area of ~72,000 sq. km. The climate of the basin is perhumid in the northwest, through humid, moist humid, dry subhumid to semi-arid climatic zones. The two major distributaries commence at Srirangam Island where the river has been dammed since the 2nd century AD [the Grand Anicut]. The main distributary, the Coleroon, also is dammed in the 1830's.
From it's headwaters the river flows eastwards down the eastern Ghats as a series of waterfalls. The Cauvery divides at Srirangam, where the northern fork becomes known as the Coleroon River. which flows for about 60 km to split into distributaries in the Porto Novo area.
The Cauvery River has a moderate sized delta that commences at Trichinopoly. From its source the river flows eastwards to join the Bay of Bengal through five distributaries in Tamil Nadu. The apex of the Cauvery Delta is about 30 km west of Thanjavur and the area of the deltaic plain is often called the garden of southern India. The main staging point for work in the delta is the town of Chidambaram positioned on the banks of the Coleroon River.