The river Cauvery has been the inspiration for various civilizations who have thrived on the banks of the river. This can be seen manifested in the various forms of art, culture and philosophy that have originated along the course of the river.
From its birth in Talakaveri till it merges with the Bay of Bengal, a journey from western ghats to the deltas of eastern coast of India, is beautifully captured by Clare Arni and Oriole Henry in this section. Please click on any place that interests you to read about its history and cultural importance. You can click on the links right here.
Cauvery is an easterly flowing river of the Peninsular India that runs across three of the southern Indian states i.e. Karnataka, Tamil Nadu, Kerala and a Union Territory of Puducherry. The fourth largest river of southern region, begins its 800 km long journey from the Western Ghats; traverses through Mysore plateau and finally forms a delta on the eastern coastline of the subcontinent before falling into the Bay of Bengal.
The point of origin of Cauvery, Talakaveri is in the Brahmagiri ranges of the Western Ghats at an elevation of 1341m. Geologically, the basin forms a part of the South Indian Shield. The shield areas of the world are considered to have preserved early-formed crust (prior to 2500 Ma). The rocks in the entire basin are predominantly metamorphic and igneous; however sedimentary rocks are exposed along the eastern margin.The eastern deltaic area is the most fertile areas in the basin and the soil type is alluvial in this region. The principal soil types found in the basin are red soils, black soils, laterite, alluvial soils, forest soils and mixed soils. Red soils occupy large areas in the basin. The basin is characterized with a unique forest with some of very distinct fauna and flora and is home to many sanctuaries and National Parks. Average density in the population is around 192 persons per sq km. which is far less than the national average, but demographic changes expected in near future and also in recent years may lead to higher population density in the catchment, especially in some of the urban centers. Historically important urban centers were Mysore, Thanjavur and Madurai whereas Bangalore, Mysore and Tiruchirapalli are the major urban centers of today. An average annual surface water potential of 21.4 km3 has been assessed in this basin. Out of this, 19.0 km3 is utilizable water. Cultivable area in the basin is about 5.8 Million ha, which is 3.0% of the total cultivable area of the country. Present use of surface water in the basin is 18.0 km3. The hydropower potential of the basin has been assessed as 1359 MW at 60% load factor.
At Talakaveri, in the south west corner of Karnataka, the cauvery,the Ganga of the south, is born high up in the green Brahmagiri mountain at an elevation of 1340 m above sea level. At a height of 1500 m at Mudigere, in Western Ghats one of the main tributaries of the river Hemavathi originates. The regional slope runs in the eastward direction.
The upper reach of the basin is covered with hill ranges of the Western Ghats and the sub basins area is broad and open with gently undulating country. In the north-west and south, there are a number of hill ranges which have steep slopes.
Some parts of the upper catchment area in the district of Hassan and Coorg are at an elevation of 1000 to 2000 m above mean sea level(msl), whereas going eastwards the average elevation of the rest of the Mysore Plateau is around 600 m to 1200 m above msl. The slope is towards east and the delta regions in the east in Tamil Nadu have an elevation of 300 to 600 m above msl. Further eastwards, land slopes very gently into the sea with average elevation < 300m above msl.
Between October and November, depending on the calculation of local astrologers, the cauvery bubbles up in rebirth. Thousands of pilgrims climb up past Kodagus' coffee estates, to the forest covered Western Ghats to cleanse themselves of their sins in the tank built around her holy waters.
From peak of the Brahmagiri I saw shimmering in the west the golden line of the Arabian Sea,but the Cauvery does not run down to it, instead she turns her back and races in a steep drop to Bhagamandala,the first sangam. Here the river Kanaka joins the cauvery swelling her waters and to commemorate this union there is nearby a temple dedicated to Shiva with copper roofs curving up at each corner into the rearing heads of cobras. It is a much grander Kerala style temple than the shrines dedicated to Ishvara and Ganapati at Talakaveri. In a large courtyard are several shrines with tiny brass rimmed doors leading into the darkness that cloaks the gods.
On the ceilings are painted carvings of birds, demons, men dragging chariots, Krishna playing his flute as his women dance and bows with arrows drawn for battle. From here the cauvery runs down, meandering more as she grows when other rivers join her, feeding the plains and then out at the east coast into the Bay of Bengal.
Somnathpur is a small Brahmin settlement far from anywhere except the Cauvery, with a twisting line of trees following the river's course. The complex was built in 1268 by Somanatha Danayaka the commander of the Hoysala army. Such projects, financed by the king or military figures, were common in the Hoysala period and were often a political statement.
It was a way of declaring a royal presence, particularly when the Hoysala kingdom had become large and difficult to control.
If friezes carved on a star shaped temple were how the Hoysalas showed power, then the Keshava temple is carved so exquisitely it is easy to forgive the statement of supremacy. Hidden behind a high compound wall is one of the finest examples of Hoysala architecture, a small gem of a temple covered in astoundingly well preserved sculptures, where no two friezes are alike. They are carved in panels of high relief so at points I could curl my finger around the back of a small figure and, despite the flattening light of the midday sun, every scene from the Mahabharata, Ramayana and life of the Hoysala kings stood out with dark shadow outlines. I walked around the temple, following each story as warriors and elephants marched into battle, Vaishnava deities sheltered under a thick canopy of foliage and Arjun pierced with his arrow the eye of a fish high up on a revolving wheel. Around and around I walked and like a great book it gave me something new each time I looked again.
Large dunes rise up at the end of a street in the village of Talakad as if they had been made for a movie set. A sudden desert in the lush Cauvery basin. These shifting sands have covered the fifth to tenth century Ganga dynasty capital, which was later an important centre for both the Cholas and the Hoysalas.
Its political significance was due to its location in both a rich agricultural basin and on the trade route linking Karnataka with the Tamil plains. The geological explanation for the dunes is that Talakad is set on a sharp bend in the Cauvery and, because the river flow is hindered, sand has built up on the inner bank blowing up into dunes. I prefer the mythological explanation surrounding the seventh century queen Rangamma, who had gone to meet her husband in Talakad where he was battling with the king of Mysore. She arrived to find her husband had been killed and threw herself into the Cauvery cursing that Talakad be buried in sand, for where she jumped into the river to become a whirlpool and for the Mysore dynasty to end for lack of an heir. All are still true. The Maharaja of Mysore has not had a direct line of descendants and successive archaeologists dig up buildings, only for the sands to cover them again.
The Vaidyeshvara temple (an important pilgrimage site, where Panchalinga, a bathing festival is held) and the Kirtinarayana temple remain uncovered largely due to concrete walls that keep the sand at bay. Walking to see the unearthed temples, only a fraction of the estimated thirty submerged, I thought I could feel Talakads' palaces, temples and houses sleeping beneath my feet as if they had drowned that day in sand.
Everywhere in the temple town of Kumbakonam, at the heart of the cauvery delta, worship was noisy and social not like the whispering of the dark, cold churches of my childhood. Around the sacred Mahamakam tank, where every twelve years the nine sacred rivers of India come to cleanse themselves of human sins, there were kum kum, fresh coconut and tea sellers nestled under the shade of ancient temple carts.
The scent of garlands sweetened the air and shops selling glass bangles twinkled rainbows of light onto men making bronzes by burning wax effigies into the shapes of gods.
"See there, the carving can be an elephant or a bull. There the women are helping their friend give birth. Around the pillars watch the goddess Parvati prepare with joy and dancing for her wedding."
By the time the cauvery reaches the sacred site of Srirangam, the river is an enormous one kilometre across and so it was only in the distance that I saw the light blue gopura of the Ranganatha Temple. It was not until I reached the island that I realised this was only the first of twenty one in the massive sixty hectare site.
Several dynasties had a hand in constructing this complex, but what now stands are largely reconstructions by the Vijayanagars and Nayaks in the seventeenth and eighteenth centuries after devastating Muslim raids.
The mythical origin of the temple is that Vibhishana was on his way back to Sri Lanka with a Vishnu shrine given by Rama as a reward for helping him defeat Ravana. He stopped to greet the Chola king at Srirangam but when he tried to leave found that he could not lift the temple because Lord Ranganatha wanted to stay.
Seven concentric high stone walls encircle the main shrine. The first three hold priests houses and shops selling everything from brass and steel kitchen utensils to guide books and brightly painted pottery animals. In the next four enclosures are shrine after shrine; the Venugopala with its high-relief sculptures of Krishna and female musicians and another where I thought I could see the eyes of the Deity, red and bulbous peering out at me until two priests beckoned me in. I had only been looking at its torso. "Garuda, Garuda." the priests told me, pointing up at the huge statue towering over us and then flapped their arms to illustrate. There were also tanks, the thousand pillared hall and the beautiful Sheshagirirayar Mandapa with its eight pillars sculpted into almost three dimensional rearing horsemen trampling tigers and European warriors. In the centre under a gilded roof Ranganatha lies on the serpent Ananta facing out across the mango topes to Sri Lanka as he had promised Vibhishana.
This waterfall was the first in India to be harnessed into electrical power in 1902 by engineers from the General Electric Company of the United States. The British needed to supply the Kolar Gold mines one hundred miles away. It is thought the gold was discovered as long ago as 77AD when a Roman historian mentioned gold and there is a legend that a herdsman during the Chola period created his own kingdom in the area after discovering treasure.
These were only surface mines, the gold seams the British discovered in the nineteenth century required deep shaft mining and therefore power to light and dig. In 1903 these were the longest lines of high tension electric transmission in the world and Kolar is still the deepest mine in the world. By the end of the nineteenth century a brand new colonial town had sprung up that they called 'Little England', with sprawling bungalows, gymkhanas and club houses. Eventually the mines were nationalised in 1956 and then closed in 2001, and they say little England is now a ghost town but the hydro plant continues to supply power to Mysore and Bangalore.
The Grand Anicut, though later rebuilt by the British, is believed to have been built in the mid to late Chola times. It is a vast construction for its time, spanning a thousand feet across the Cauvery and sixty feet wide. The Chola monarchs needed the dam to tackle the problem of using the flood waters of the cauvery for irrigation to create more consistent food and wealth.
The Grand Anicut stands just after the Srirangam Island diverting water into a network of channels that feed the Cauvery delta to the east. This was part of an agrarian system that the Cholas founded, which remained largely unchanged till the nineteenth century, based on a skilful use of river channels, wells and reservoirs. British nineteenth century irrigation specialists wrote of the virtual completeness with which 'surface irregularities' had been used to hold water and found little need for the construction of new ones.
This irrigation technology was part of the system of authority and governance of their vast empire during the ninth to twelfth centuries. The Cholas controlled this system by granting water rights, just as they would land rights, to kinsmen, military chiefs, royal retainers, village officers and especially religious institutions. These rights were a way of renewing political alliances or securing military support and this created a system of control where areas governed themselves but would still remain faithful to the king. Broadly speaking this meant rich peasants dug wells, chiefs built tanks, and kings built large dams.
Thanjavur was the capital for almost a thousand years for the Cholas (9th-13th centuries), the Nayaks (1535-1676) and the Marathas (1676-1855). The Cholas defined the agrarian structure in this 'rice bowl of Tamil Nadu' where the fan of the Cauvery Delta was irrigated to give the lowlands a source of almost constant water.
The power and money this gave the Chola Empire, which stretched across most of the Indian peninsula, meant Thanjavur became a centre for the arts. Music, dance, bronze sculpture, painting and of course architecture thrived, the greatest example of which is the Brihadishvara temple built by Rajaraja in 1010.
I got my first view of this Unesco World Heritage site in the golden evening sun, but the light did not soften the two huge sculpted dvarapalakas standing guard on the gate, teeth like fangs and brows furrowed, their feet seemingly raised ready to crush me. The monumental temple dedicated to Shiva, with its tall tower, twenty foot long Nandi and four meter high lingam, is however built with a balance of proportion and simplicity of ornament that seem to humanise it. Even Sarasvati, Bhikshatanamurti and Nataraja were approachable with the red light of the setting sun coating their pale granite bodies.
On the other hand the royal palace in Thanjavur is a confusing rambling building built by the Nayaks and added to by the Marathas. It was under renovation when I went so I stumbled down dark corridors to the Durbar Hall, a suddenly bright room painted with gods, angels and court figures, built by Shahji II in 1684. After a series of bad directions I followed a serendipitous goat to another gallery which contained part of the huge eclectic collection of Maharaja Sarfoji that forms one of the most important reference libraries in India.
Despite the noise of the workmen in the Rajaraja museum the Chola bronzes and sculptures, like Shiva and Parvati's wedding, seduced me into a reverie. I felt like I had at the Brihadishvara, like an audience in the dark, captured by the performance on stage.
I set off to the town of Nagore excited about seeing the funeral shrine (dargah) of Hazrat Shahul Hamid (1491-1570) which is so famed for its healing powers that Indians of all religions come and are made welcome. Tamil biographies of the Muslim saint's life are filled with miracles that occurred both during and after his lifetime.
When I arrived at the once famous port it had unseasonably poured with rain in the night. The streets were rivers which the pilgrims had to wade through and the five white minarets were grey from the downpour.
The tomb, with beautiful domed arches and doors covered in sheets of embossed silver and gold, was built with money from the Maratha rulers of Thanjavur and prominent Muslims of Nagapattinam. The land was given to the saint during his life time by Shevappa Nayaka in gratitude for curing his son. Inside the bare pillared room of the shrine the smell hit me, a sharp odour of medicinal disinfectant and the stale breath of the sick. Then I heard the children crying and under it were the sobs of adults, along with the repetitive pleas of the prayers being sung.
At the back was a corridor with glass frames hung on the walls in which were assortments of broken glass, hair, and rusty nails with a name and date underneath. A man told me "This is what we have taken out. The bad spirits that were making them sick." Obvious really, if I had thought about it, that the saint's fame for healing would summon, not just the devout, but the desperate.
When I arrived in the traditional temple town of Chidambaram the streets were full of hundreds of pilgrims who had come for the festival at the ninth century Nataraja temple. Shops selling flower garlands, coconuts, and multicoloured kum-kum lined their path, and hand turned mini Ferris wheels echoed with the screams from the children inside.
Inside the enormous ninth century Chola temple compound, with its four towering gopuras, thousands of pilgrims headed for the sanctum with its gold plated roof past the intricate sculptures detailing the one hundred and eight movements of Bharat Natyan. Dikshitar Brahmins, whose hereditary role is to run the temple, wandered amongst them in the thousand pillar hall, where Chola kings had once been crowned. In the Golden Hall Shiva is said to have performed his cosmic dance of creation and destruction and at the Shivaganga tank I watched as an old man gently eased his nervous wife into the water for a ceremonial cleansing. Outside a group of musicians stood near the huge temple cart, puffed up with their own importance, waiting for the procession to begin. At the top of the cart, hidden beneath a waterfall of flowers, was the statue of Nataraja. After much shouting and delay, two queues of pilgrims formed along the ropes at the front and began to inch it forward, the cart lurching precariously with each heave.
For some quiet relief from the busy festival,I drove out to Pichavaram and its mangrove swamps at the northernmost point of the Cauvery delta. Four thousand channels, like tunnels of enmeshed roots too thick to see through with entwined leaves overhead, crisscross the swamps creating thousands of islands. In the shallow waters fishermen waded through the clear waters, their catches of shrimp hanging in plastic bags at their waists. Women's giggles and cries continually pierced the air as their more heavily tourist laden boats got stuck in the shallower waters but it was almost quiet when I rounded a corner and met two coracles coming hurtling towards me, the small boys manning them shrieking, "Cooool drinks!"
At the quiet village of Hogenakal nestled in the forested Melagiri Hills is a waterfall where the Chinnar River meets the cauvery. Despite its remoteness the place was buzzing with people who had come to bathe in the curative waters. Apparently properties from the forest the Cauvery travels through, in what was Veerappan territory, are what make the waters healing.
To get to the falls themselves I had to cross one fork of the river by coracle and then walk down into the gorge along a slippery path where the river had, in the monsoon months, moulded the rocks into smooth sculptures. We pushed off from a small sandy cove and rowed up stream towards where the second fork of the river plunged down in frothy, bubbling cascades, its spray glistening into ephemeral rainbows that appeared and disappeared as the river buffeted our coracle. I could see both why films used this location as a backdrop for love scenes and how real life tragic lovers could easily end their lives here. The boatman, puffing and straining, continued to bring us closer to the thunderous falls, until a fellow passenger, shouted out to him.
"I am my mother's only son. I am my mother's only son."
The boatman lifted his paddle and the Cauvery took the coracle gently down stream between high, barren, granite cliffs on which fishermen perched, dangling their lines into the water. There seemed to be only uninhabited forest stretching into the distance as far as the eye could see and so I was surprised to see, up on the bank, a solitary drinks shack. I thought it an odd place for a bar until I remembered that one side of the river was Tamil Nadu and the other Karnataka. As I watched, a man staggered down from the outdoor bar into his coracle, stopped a passing boat, a mobile tobacco shop, bought a smoke and, with a loud, tuneless song, made his way in meandering circles back to the Tamil Nadu bank.
By the time I reached Poompuhar a storm was approaching. The wind whipped the rain in circles and churned the sea into froth above the submerged ancient city. I pushed my way through the blustery weather, along the black sand, searching for the mouth of the Cauvery.There was nothing left of the once great port where the Cholas had traded with Rome and then I found the pitiful little stream that was the Cauvery.
Looking back out into rough surf of the Bay of Bengal I could see how Atti the lover of the Chola princess Adimandi could have been dragged away by the tides. I could not see this brook as the great Cauvery, the Ganga of the south. This could not be the beautiful mythical girl given by Brahma to the childless king Kaveran, the woman who went on to marry Sage Agastya. The wife whom he promised he wouldn't leave alone, and then teaching a difficult philosophy lesson to his disciples, he forgot and did. Cauvery, convinced something had happened to him, threw herself into a tank to drown but miraculously sank to the bottom, went underground and became the river Cauvery.Sage Agastya searched for her and eventually recognised Cauvery in the spring at the Brahmagiri Mountains and she agreed to return to him, but half of her, she said, would always remain as the river Cauvery to enrich mother earth.
On the opposite bank of the tiny river I saw a burning burial pyre. Smoke and flames, lashed by the wind, rose and fell against the dark sky protesting at death and I realised it was my own feelings that tempered my view of the river. Cauvery had done what she promised, giving and sustaining life across two states, and now she was free to rest in the arms of the sea.
In the Bay of Bengal, towards the base of the Cauvery Delta, is the small village of Velanganni which is famed for its healing powers. In the 16th century it became known as the place where the Virgin Mary miraculously appeared to two small boys instructing them to ask for a chapel to be built.
The Roman Catholic basilica, raised to this status by the Pope in 1962, has been renovated and extended many times and is now a large neo gothic building that seemed, when I arrived, to shine out from its whitewashed steeples and buttresses. Stalls nearby sold images of Our Lady of Good Health and small silver replicas of parts of the body visiting pilgrims might want cured as well as simply objects they might want like a house, car,or baby. I decided a house would be useful, thereby escaping my mad landlady.The church was light and airy and the crowned Virgin seemed so benevolent in blue, holding baby Jesus at her side, as I posted my little house into the box at the altar.
The best of the talismans, specially made by jewellers, are kept in a museum opposite. Rows of cases display, along with letters of thanks and photos; hearts modelled straight from an anatomy book, three-dimensional houses, mini coconut fields and lots of stethoscopes. The moving ones were the proud mothers cradling their new born babies, which they had waited so long for. Room after room of these talismans and I began to really believe there would be a nice little house waiting for me when I got home.
King Christian's resources though were small and despite the fledgling colony setting up two routes trading in pepper and cloves their profits were also small. In the early 1640's the new king Fredrick III was more worried about war in Europe and so trade with Denmark stopped and the colony was all but forgotten for thirty years.
In 1669 trade was resumed and reinforcements were sent along with Lutheran missionaries. It is largely during this period, the late seventeenth to eighteenth centuries, that the now somewhat decayed baroque town gate with its Danish coat of arms and once grand houses and churches along King Street were built. After the Napoleonic wars Denmark's finances were in bad shape so they sold the colony to the British East India Company.
When I went the town was largely deserted except for a few fishermen mending their nets and children who tried to sell me old Danish coins. The New Jerusalem Church built in 1718 was still in use and is thought to be the first Lutheran mission in India, but is more famous for the missionary Bartholomaus Zigenbalg who translated the bible into Tamil and in doing so brought the printed word to India. On the north side of a large square is the once imposing colonnaded Governor's bungalow where he lived but most extraordinary was the still impressive Dansborg Fort. This example of Scandinavian military architecture seemed the perfect icon for this rare outpost of Danish culture in the Indian Ocean.
Everywhere I looked in Srirangapattana, on the island created by the Cauvery splitting and joining again, there were the ghosts of history. As a strategic site, with a natural moat, centuries of rulers fought over the land but it is most famous as the capital of Tipu Sultan the ruler of much of southern India.
'The Tiger', as his subjects called him, was a charismatic king, who hired French mercenaries to try and keep the British at bay. Finally in 1799 the British stormed Srirangapattana with its formidable ramparts and killed Tipu, mistaking 'the Tiger' for just another soldier.
Although the British destroyed most of the buildings including Tipu's palace much of the impressive fortifications still stand and the stories are there if you listen. In the vaulted dungeons where the British were kept prisoners, at the Water Gate where Tipu was killed after being betrayed by one of his courtiers, at the summer palace with its murals of Tipu's father's victory over the British and at the Gumbaz where both men are buried.
Srirangapattana has also always been an important religious site on the sacred island where the goddess Cauvery herself asked Ranganatha to come and stay. The Sri Ranganatha temple and the Jami mosque were left untouched by the British and everywhere there are ghats leading down into the Cauveri. At the Kings bathing ghat I noticed a large cage half in the water and another story danced out of the reflections of the river. It was built so the kings could bathe without being sucked away by the currents but, unfortunately, only after one of the royals drowned. All his entourage were with him but as commoners they were forbidden to touch the king, so they stood by, letting him drown.
The climate at the basin level generally remains dry except for monsoon months. There is a considerable variation in the mean daily maximum and minimum temperatures across the catchment. The mean daily maximum temperature ranges from 19.5 to 33.7O C, whereas the mean daily minimum varies from 9.1 to 25.2O C.
Maximum temperature in the western areas, having high relief, such as Mercara is in the month of March (28.5 OC). Wind in the area is linked with the monsoons and so mainly blows from the directions between the south-west and north-west during the south-west monsoons. Clouds are also associated with the monsoon activity with the skies being generally overcast during the monsoons.
Precipitation varies considerably across the basin. While, the western side of the catchment mainly experiences the south-west monsoon from June to September; north-east monsoon from October to December falls on the eastern side. The rainfall during the rest of the period is insignificant.
The maps below show the level of precipitation in the basin in four different months. Maximum rainfall happens in the month of August and even this month shows considerable variation across the basin with the western margin getting the bounties. Rainfall in the months of October and November is of comparable level; except for the fact that the maxima in the month of October is in the western part of the basin, whereas for the month of November, the highest rainfall region shifts to eastern margin. Quantifying the total rainfall in the basin across the year; about 50% is received during the south-west monsoon, about 33 % in the northeast monsoon, roughly 10% in the pre monsoons and the rest in the winter months. The total number of rainy days is more than 100 per year in the western part of the basin and 40 to 50 elsewhere in the region.
March is a dry month for the entire basin. However, some patchy areas in the south western part of the basin get some rainfall. August is one of the wettest months in the year. Highest rainfall zones are the western margins of the basin whereas there is very minimal rainfall in the eastern margin of the basin. Intensity of rainfall in Kodagu area of Karnataka is very high in these months. There is some rainfall in the western and also in the eastern edge of the area. However areas in the central part of the basin remain dry. High rainfall area shifts to the eastern margin of the basin leaving north western regions dry.
Summer weather being dry, the humidity is low. The relative humidity in the basin ranges from 49 to 86. The mean relative humidity is high during the monsoon period and comparatively low during the post monsoon period.
The far north western part of the drainage basin has a humid climate which passes eastwards into humid, moist sub-humid, dry sub-humid and semiarid zones. Nearer to the sea, relative humidity increases again.
Mean Annual Humidity in Cauvery Basin |
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| Station | Humidity(%) |
| Mercara | 81 |
| Hassan | 69 |
| Mysore | 64 |
| Coonoor | 64 |
| Coimbatore | 64 |
| Salem | 62 |
| Trichy | 61 |
| Nagapattinam | 72 |
Read More
CPCB, 1995: Comprehensive report on the basin
Precipitation varies considerably across the basin. While, the western side of the catchment mainly experiences the south-west monsoon from June to September; north-east monsoon from October to December falls on the eastern side. The rainfall during the rest of the period is insignificant. The maps below show the level of precipitation in the basin in four different months.
Maximum rainfall happens in the month of August and even this month shows considerable variation across the basin with the western margin getting the bounties. Rainfall in the months of October and November is of comparable level; except for the fact that the maxima in the month of October is in the western part of the basin, whereas for the month of November, the highest rainfall region shifts to eastern margin. Quantifying the total rainfall in the basin across the year; about 50% is received during the south-west monsoon, about 33 % in the northeast monsoon, roughly 10% in the pre monsoons and the rest in the winter months. The total number of rainy days is more than 100 per year in the western part of the basin and 40 to 50 elsewhere in the region.
Read More
IWMI-CGIAR World Climatic Database
CPCB, 1995: Comprehensive report on the basin
Cauvery basin spans an area around 81155 km2 and runs from a northwest to south eastern direction along a general south easterly slope. Catchment area of this basin can be divided into three sections; upper catchment areas with steep slopes; middle catchment area mostly in Tamil Nadu and lower catchment area which is confined to the plains in Tamil Nadu.
Tributaries of river Cauvery
Around 81155 km2 area comes under the Cauvery basin, which is nearly 2.5% of the total geographical area of the country. The basin is located between 1007 N and 13 0 28 N and 75 0 28 E and 79 0 52 E. The catchment of the river basin lies in the states of Karnataka, Tamil Nadu, Kerala and Union Territory of Pondicherry.
Of the total area of the basin, 41.2% falls in the state of Karnataka, 55.5% in the state of Tamil Nadu and 3.3 % in Kerala. The width of the basin ranges from 65 to 250 km. The total length of the river from its source to its outfall in Bay of Bengal is about 800 km of which 320 km is in Karnataka, 416 km in Tamil Nadu.
Cauvery river flows from NW to SE and drains about 81155 km2 of the southern peninsula. and the river has been dammed since 2nd Century AD at the Grand Anicut. The drainage network of the river is dense and the river forms a delta at Trichinopoly.
The table below gives the details of the tributaries of the river Cauvery.
Tributaries of Cauvery |
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| Tributary Name | Catchment Area (Sq.km) | Origin, Altitude,Length | Sub-Tributaries | State |
| Arakavathy | 4351 | Nandidurga 1480 metres 161 km |
Kumaudavathy, Manihalla, Kuttehole, Vrishabhavathy | Karnataka and Tamil Nadu |
| Harangi | 717 | Pushpagiri Hills of Western Ghats. 1067 metres 50 km |
Karnataka | |
| Hemavathy | 5410 | Ballarayana Durga in Western Ghats 1219 metres 245 km |
Karnataka | |
| Kabini | 7040 | Western Ghats in Kerala 2140 metres 230 km |
Taraka, Hebballa, Nugu, Gundal | Karnataka, Kerala and Tamil Nadu |
| Lakshmana Thirtha | Western Ghats 1950 metres 131 km |
Ramathirtha | Karnataka | |
| Shimsha | 8469 | Tumkur District 914 metres 221 km |
Veeravaishnavi, Kanihalla, Chickkhole, Habbahalla, Mullahalla, Kanva | Karnataka |
| Suvarnavathy | 1787 | Nasrur Ghat Range Length 88km |
Karnataka and Tamil Nadu | |
Around 81155 km2 area comes under the Cauvery basin, which is nearly 2.5% of the total geographical area of the country. The basin is located between 1007 N and 13 0 28 N and 75 0 28 E and 79 0 52 E.
The catchment of the river basin lies in the states of Karnataka, Tamil Nadu, Kerala and Union Territory of Pondicherry. Of the total area of the basin, 41.2% falls in the state of Karnataka, 55.5% in the state of Tamil Nadu and 3.3 % in Kerala. The width of the basin ranges from 65 to 250 km. The total length of the river from its source to its outfall in Bay of Bengal is about 800 km of which 320 km is in Karnataka, 416 km in Tamil Nadu.
Cauvery basin is bounded on the north by the ridges separating it from Krishna and Pennar basin, on the south and east by the Eastern Ghats and on the west by Western Ghats
In the map, the area in Hectares is given for all the districts that fall within the Cauvery basin in the area. The bigger districts are shown in dark green tone. Please note that this map is based on older data and hence administrative boundaries may not confirm to the actual administrative boundaries.
State wise area in Cauvery Basin |
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| State | Karnataka | Kerala | Tamil Nadu | Pondicherry | Total |
| Catchment area in sq.km of Cauvery basin | 34273 | 2866 | 43867 | 149 | 81155 |
Cauvery basin forms a part of the South Indian Shield that preserves an early formed crust (>2500 Ma). In terms of rock types, metamorphics and igneous rocks predominate throughout the basin which mark major events of volcanism, plutonism, metamorphism and sedimentation.
Charnockites, high grade schists, migmatites, green stone belts and consolidated gneisses of Archean age are the most commonly found rocks. Southern part of the basin is characterized with laterised and ferruginous sandstone. Certain coastal areas also have conglomeratic sandstone, coralline limestone and shale. Around 38,000 sq km of the area in the basin is covered by hard rock and around 11,000 sq km by sedimentaries comprising mainly the delta portion.
Source CPCB, 1995: Comprehensive river basin report
Soil types vary all across the basin but the red soils are the predominant category of soils followed by black soils. The highland areas which fall in Karnataka have lateritic soils, reddish brown in colour. These soils are shallow, acidic to neutral and are fertile, good for agricultural practices. Highlands of Kerala also have red loam soils along with some areas of black soils which are fertile, rich in organic content and because of high nitrogen content are excellent for agriculture.
Lowlands and plains of Karnataka have reddish brown soils which are neutral to acidic in nature and are well drained. In some lowlands though, the soils are neutral to weakly alkaline and have higher water holding capacity.
The soils in Tamil Nadu on the other hand are deep soils with increasing depth towards the coast. These soils have high clay content, low draining capacity, poor nitrate, poor phosphorus and high potassium and lime content. In the south eastern corner of the basin, some area is swampy which is predominantly alluvial clay with poor drainage.
Classification of Soil types in the Cauvery Basin: (CPCB, 1995) |
|
Colour of Soil |
Location |
| Red Loamy | The Eastern slope of Western Ghats in Karnataka State and upper reaches of the Karnataka basin area around KR Sagar & also entire Vrishabhavathi valley south of Mandya |
| Red Sandy | Bhavani sub basin of Palghat Disttin Kerala, Major part of the middle and lower Karnataka basin, Tanjavur, COimbatore, Nilgiris, Periyar, Dharmapuri, Anna, Salem in Tamilnadu |
| Laterite | A small part north west of Mercara, a small part in Wayanad Distt of Kerala State |
| Forest Loamy | Wayanad District of Kabani basin |
| Loamy Organic | Coimbatore district of Tamil Nadu |
| Medium Black Soil | Idukki District of Kerala State |
| Reddish Brown | Thanjavur, Tiruchim Salem, Periyar, Anna & Coimbatore District. |
| Black | Thanjavur & Coimbatore District of Tamil Nadu |
| Sandy | South Arcot |
| Alluvial Clay with around 50,000 Ha of Sand | Extreme south-east corner of the Cauvery basin |
Major share of the available water of the basin is utilized by agriculture. Over 90% of the water of the river water is abstracted for irrigation. The river has been exploited for Agriculture from 2nd Century onwards. Water for irrigation is abstracted through wells, borewells, canals, tanks and lifts.
Domestic use, both urban and rural make around 6% of the total water use in the basin. The map of the urban consumption shows urban centres like Bangalore and Mysore with highest demand for domestic water and some demand from commercial sector as well.
Although industrial consumption is fairly less compared to agricultural consumption, the map shows Erode with highest demand for water in the industrial sector.
Cauvery basin includes around 11,000 sq km of sedimentaries in the delta region and the remaining area is occupied by hard rocks. In granite region, weathered zones form the shallow aquifers, the average depth of weathering is around 15 m.
Deeper semi confined to confined aquifers occur at depths more than 200m as well, as the fractures are very deep seated. In some areas underlain by crystalline rocks, ground water is limited to fractures, joints and weathering. While weathered gneisses can yield upto 400 m3/day, unweathered rocks and charnockites yield only around one tenth of that. Potential aquifers occur in various part of extensively weathered and fractured hardrocks. As extensive development has already taken place in some areas, further development should be done with caution. Several areas in the basin seem to have Fluoride content more than 1.5 ppm in the ground water.
Potential aquifers occur in the sedimentaries and so western part of Cauvery delta may have a potential for future groundwater development. The eastern margins of the delta are slightly mineralized and so caution is required to exploit this further along with considering issues like salt water intrusion.
Net draft of groundwater
Net draft in million cubic metres (MCM) is shown in this map for year 1995. Net Draft is over 500 MCM for most of the districts of Tamil Nadu, while most of the areas in Karnataka show a net draft of less than 500 MCM a year.
Groundwater usage is more than 205 MCM a year in coastal regions of Tamil Nadu. Up the slope towards north westerly direction, there is lesser and lesser ground water being used for domestic, industrial and other uses.
Groundwater exploitation in Tamil Nadu is shown in this map. The red regions depict areas which are over exploited and include Salem, Namakkal, Coimbatore, Dharmapuri, and some areas of Nagapattinam. Other critical and semi critical areas are also shown. Safe areas are Nilgiris and Tirucharipalli districts.
Available groundwater potential in the Cauvery is over 545 MCM a year in the coastal areas along the south eastern margin of the basin. The same potential is also available in Mysore, Mandya and Chamrajnagar.
Water Quality in the Cauvery basin is constantly being monitored at some chosen stations all along the length of the basin by Central Pollution Control Board (CPCB).
Although there are very many parameters to determine the quality of the surface water such as turbidity, total dissolved solids, dissolved oxygen, biological oxygen demand (BOD), chemical oxygen demand (COD), chlorides, sulphates, nitrates, total coliform bacteria, only some of the parameters are discussed in more detail of all the parameters discussed here, Cauvery waters perform well wrt pH and nitrate level, but perform poorly for BOD, COD and total coliform.
Water used for agriculture, domestic, or industrial processes is returned to the river as waste water. Because of the large scale abstraction of water, negligible flows during some months, the river gets polluted by both point and non point sources. Intense human and cattle population, pollution from agriculture and especially from industries and untreated or partially treated sewage is altering the water quality of the river severly.
This maps shows data only from Tamil Nadu part of the basin. Effluent discharged in litres per day is maximum from Salem, Tiruchirapalli and Nilgiris. Namakkal district in this map shows minimal effluent discharge in the basin.
Maximum waste water discharged into the river again is from Salem, Tiruchirapalli, Nilgiris and Coimbatore. This maps shows data only from Tamil Nadu part of the basin.
Biological Oxygen Demand (BOD)is measured at eleven monitoring stations along the Cauvery river. BOD indicates the extent of organic matter pollution in the water.
The map clearly shows that BOD levels are more than 5 mg/l for all the monitoring stations. Comparing this with the designated best use for water (CPCB, 1995) with BOD as the main criteria (Table below); water of the river cannot be recommended for drinking, with or without treatment, or for out door bathing and for wild life and fisheries
Classification of surface water in India |
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| Designated Best Use | Class | Biological Oxygen Demand Criteria |
| Drinking Water Source without conventional treatment after disinfect ion | A | 2 mg/I Max |
| Out door bathing (organised) | B | 3 mg/I Max |
| Drinking Water with conventional treatment followed by disinfection | C | 3 mg/I Max |
| Propagation of wild - life fisheries | D | |
| Irrigation Industrial cooling controlled waste water disposal | E | |
Chemical Oxygen Demand (COD) levels in the basin are again on the higher end. There is also a gradual increase in the COD levels as one goes downstream, the maximum being at the south easternmost monitoring station. The standard data from CPCB for COD levels is not available for comparison.
pH values for all the monitoring stations fall within the class A category as per CPCB classification which is nearly neutral for most of the stations. At some points it is slightly alkaline but within the permissible limits.
| Classification of surface water in India | ||
| Designated Best Use | Class | pH Criteria |
| Drinking Water Source without conventional treatment after disinfection | A | 6.5- 8.5 |
| Out door bathing (organised) | B | 6.5- 8.5 |
| Drinking Water with conventional treatment followed by disinfection | C | 6-9 |
| Propagation of wild - life fisheries | D | 6.5- 8.5 |
| Irrigation Industrial cooling controlled waste water disposal | E |
6-8.5
|
Coliform content for drinking water is measured in terms of Most Probable Number per 100 ml. Total coliform bacterial count indicates the incursion of untreated municipal sewage into the river. None of the monitoring stations on the river can be classified as class A by this parameter, that implies that the water is not safe for drinking without conventional treatment.
Very few places appear to fall in category B, that implies out door bathing is the designated best use for the water at those places. Some of the monitoring stations seem to fall in the class C, that implies that water can be used for drinking after conventional treatment. Please note that this data is based on a 1995 study done by CPCB and hence the quality of the water may differ considerably in the current samples.
Classification of surface water in India |
||
| Designated Best Use | Class | Total Coliforms Criteria |
| Drinking Water Source without conventional treatment after disinfection | A | MPN/100 ml ? 50 |
| Out door bathing (organised) | B | MPN/100 ml ? 500 |
| Drinking Water with conventional treatment followed by disinfection | C |
MPN/100 ml ? 5000 |
| Propagation of wild - life fisheries | D | - |
| Irrigation Industrial cooling controlled waste water disposal | E | - |
Broadly, land use in the basin can be divided into four categories; arable, non arable, forest land and land for habitation. More than 50% of the land area in the basin is arable, which implies that it can be cultivated. About 21.6% of the land is non arable. Total forest cover in the basin comes out to be 19.53% and the rest of the area is inhabited. Among the inhabited areas, rural and urban areas form two distinct kinds of habitations.
In Tamil Nadu part of the Cauvery basin, around 73.7% of the population lives in rural areas. In Karnataka, rural population comprises 60.47% whereas in Kerala the population is completely rural. Total number of villages in the entire basin are around 17356.
For an example, Taluk level maps of Chamrajnagar Taluk of Karnataka are shown to get a visual idea about distribution of villages, village size, population, cultivable land, agricultural families, number of wells and per capita water available. Some overlay maps are also shown to compare two parameters together to see the possibility of any correlation.
According to the 1981 census, 31.2% of the total population lived in urban areas in the basin, which has further increased in the last two decades. Amongst the urban centres population density of Bangalore is the highest.
From around 882 persons/sq.km.in1981, it has reached around 3000 persons/sq.km. with a decadel growth rate of over 35%. Other major urban centres are Mysore in Katnataka and Tirucharipalli, Thanjavur etc in Tamil Nadu. Bangalore, Mettur and Coimbatore have a high concentration of industries followed by Mysore, Mandya, Periyar and Salem. The demographic shift towards urban areas is expected to increase the demand for water in future.
More than 60% of the total population in the basin lives in rural areas and their major occupation is agriculture. The land under cultivation in the basin is 48%. Around 24% of the cultivable area has some means of irrigation or other.
The crops grown in the area vary from region to region, however major crops are paddy, sugarcane, ragi and jowar. Apart from these, some other crops such as coffee, pepper, banana, betel vine, gingili, onion, cotton, black gram are also grown.
This map shows distribution of paddy throughout the basin. Major paddy producing areas are eastern coastal or deltaic regions of Tamil Nadu i.e. Thanjavur and Nagapattinam. Cuddalore and Pudukottai in Tamil Nadu and Mandya in Karnataka are also the areas where paddy cultivation is done at a large scale. While central part of the basin has lesser areas covered by paddy, but it can be observed that all the districts contribute to the paddy production in the area.
Area under ragi is considerably less than Paddy, but the major ragi producing region is the Mysore plateau. Chamrajnagar in Karnataka and Dharamapuri, Salem and Erode in Tamil Nadu are the main ragi cultivating areas. Some other areas that have some areas under ragi cultivation are Tumkur, Mandya and Hassan in Karnataka.
Cuddalore in Tamil Nadu is the major sugarcane growing district in the entire basin. Chamrajnagar, Dharampapuri, Erode and Namakkal are other areas that cultivate sugarcane in some areas. All other areas have less regions under sugarcane cultivation.
Mandya in Karnataka and Coimbatore, Dindigul in Tamil Nadu are the districts that cultivate jowar. Some other areas in the northwest of the basin also have some areas under jowar cultivation as in the south east of the basin. Jowar, it appears is not grown in the costal belt.
Out of the total area of the basin, the area under forest is just 19.53%. Roughly 18% of total basin area in Karnataka and 19% in Tamil Nadu are covered with forest. In Kerala part of the basin, the forest cover is much higher but considering that area forms a small part of the basin, this comes out to be negligible.
The forest cover is much below the desirable forest cover of 33%. The minimal forest cover is in the districts of Thanjavur (1.5%), Tumkur (2%) and Mandya (4.8%). Forests have been and are under great stress because of the ever increasing demand for the forest products which can be a serious threat to the ecosystem in the area.
This map shows distribution of forests in Karanataka part of the basin. Although forest cover in the basin is less than desirable, but these forests are ecologically unique and very rich. Home to some of the unique flora and fauna, the area is famous for its many sanctuaries.
Most of the districts in the basin that fall within the Karnataka part seem to benefit from the well irrigation. More than 12,000 Ha of the land is irrigated in each of the these districts of Mysore, Chamrajnagar and Tumkur. Large areas in Namakkal and Dharamapuri are also irrigated by wells.
More than 3354 Ha of cultivable land in many of the districts of the basin are irrigated by borewells. In some of the districts like Coimbatore, Namakkal, Tumkur, Erode, extent of borwell irrigation is over 24,000Ha.
More than 60,000 Ha of the cultivable land is irrigated by canals in each of Mandya, Mysore and Thanjavur districts.
More than 28000 Ha of the land in Tumkur, Cuddalore and Thanjavur districts is cultivated by Tank irrigation method. More than 5000 Ha of the land is irrigated by tanks in most of the districts across the basin.
Lift irrigation method is used mostly in Dharamapuri,Chamrajnagar and Bangalore Rural area in the basin as is evident from the map. More than 500 Ha of the land is irrigated by lift irrigation in these districts.