Cauvery River

• The Cauvery River is known as the ‘Ganga of the South’.
• It rises at Talakaveri in Kodagu district of Karnataka.
• The river is 800 km long and flows through Karnataka and Tamil Nadu before emptying into the Bay of Bengal.
• The Cauvery basin covers an area of 81 thousand Sq.km across Tamil Nadu, Karnataka, Kerala, and Puducherry.
• The basin is bounded by the Western Ghats on the west, Eastern Ghats on the east and south, and the ridges separating it from the Krishna basin and Pennar basin on the north.
• 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 and has black soils, red soils, laterites, alluvial soils, forest soils, and mixed soils.
• The basin receives rainfall from the southwest and northeast monsoons and is almost a perennial river.
• The river is used for irrigation and hydroelectric power generation.
• The Sivasamudram Falls in Karnataka supply hydroelectric power to Mysore, Bengaluru, and Kolar Gold Fields.
• 90-95% of the Cauvery River’s irrigation and power production potential is already harnessed.
• The river drains into the Bay of Bengal, and the major part of the basin is covered with agricultural land.

Tributaries of the Cauvery River

• Left Bank: Harangi, Hemavati, Shimsha, Arkavati
• Right Bank: Lakshmantirtha, Kabbani, Suvarnavati, Bhavani, Noyil, Amaravati
• River descends from South Karnataka Plateau to Tamil Nadu Plains via Sivasamudram waterfalls (101 m high)
• River branches into two parts at Shivanasamudram and falls through a height of 91 m
• Falls utilized for power generation by power station at Shivanasamudram
• Two branches join after fall and flow through wide gorge known as “Mekedatu” for 64 km, forming boundary between Karnataka and Tamil Nadu
• River enters Mettur Reservoir after Hogennekkal Falls and is joined by Bhavani tributary on right bank
• River widens and flows as “Akhanda Cauvery” after Noyil and Amaravathi tributaries join on right bank
• River divides into two parts after crossing Tiruchirapalli district, Northern branch called “The Coleron” and Southern branch remains as Cauvery, forming Cauvery Delta
• Two branches join again to form “Srirangam Island” after flowing for about 16 km
• “Grand Anicut” constructed by Chola King in 1st Century A.D. on Cauvery branch
• Below Grand Anicut, Cauvery branch splits into two, Cauvery and Vennar, and divides into small branches forming a network all over the delta.
• 
• 

HEMAVATI:

• Tributary of the Kaveri River.
• Rises in Chikmagalur District of Karnataka.
• Flows through Chikkamagalooru, Hassan District, and Mysore district.
• Joins Kaveri near Krishnarajasagara.
• Approximately 245 km long.
• Gorur reservoir built on the river in Hassan district.

SHIMSHA:

• Tributary of the Kaveri River.
• Originates in Tumkur District of Karnataka.
• Flows through Maddur.
• Markonahalli Dam built across the river in Kunigal Taluk.
• Shimshapura waterfall in Malavalli Taluk.
• Location of Shimsha Hydro Electric Project.

ARKAVATHY RIVER:

• 161 km long river.
• Originates at Nandi Hills of Chikkaballapur district of Karnataka.
• Tributary of the Kaveri River, joins at Kanakapura.
• Flows through Kolar District and Bangalore Rural district.
• Drains into the Chikkarayappanahalli Lake near Kanivenarayanapura.
• Chunchi waterfall on the Arkavathi River at Sangama near Kanakapura attracts numerous tourists.
• Water is taken from two reservoirs built on the river, Hesaraghatta and Tippagondanahalli Reservoir.

LAKSHMANA TIRTHA:

• Rises from the Irupu Falls in the Kodagu district of Karnataka.
• Flows eastward and joins the Kaveri River in the Krishna Raja Sagara Lake.
• Ramathirtha is its major tributary.

Kabini:

• Originates from Pakramthalam hills in Wayanad District of Kerala
• Forms an island called Kuruva Island after traversing 2 km from the confluence of the Panamaram river
• Backwaters of the Kabini reservoir are rich in wildlife, especially during summer

Suvarnavathy:

• 88 km long river that rises from the Nasrur ghat Range of Karnataka
• Tributary of the Kaveri River with a catchment area of about 1787 sq km
• Suvarnavathy dam is located near Attigulipura in the Chamarajanagar Taluk

Noyyal:

• Originally called Kanchinadi, it drains into the Kaveri River
• Rises from the Vellingiri hills in the Western Ghats in Tamil Nadu
• Joins with river Cauvery at Kodumudi in Erode District
• 173 km long tributary of the Kaveri River filled 32 tanks

Amaravathi (also known as Pournami):

• 175 km long river that begins at the Kerala/Tamil Nadu border at the bottom of Manjampatti Valley
• Flows in a northerly direction through Amaravathi Reservoir and Amaravathi Dam at Amaravathinagar
• Nourishes the agriculture of Erode District
• Used for industrial processing water and waste disposal, resulting in severe pollution due to textile dyeing and bleaching units, especially in the vicinity of Karur

Distributaries of the Cauvery River

Kollidam River (also called Coleroon River):

• The northern distributary of the Kaveri River in the delta of Thanjavur, southeastern India
• Splits from the main branch of the Kaveri River at the island of Srirangam and flows eastward into the Bay of Bengal
• Distribution system in Kollidam lies at Lower Anaicut, an island in the river
• Town of Chidambaram lies on its banks

Vennar River (or Vennaaru River):

• River and distributary of the Kaveri River in the Kaveri delta, flowing through the Thanjavur, Tiruvarur, and Nagapattinam districts of Tamil Nadu
• Begins at the Grand Anaicut at the eastern end of Srirangam Island, branching off from the Kaveri
• Flows eastward and splits into northern and southern branches at the Thenperambur dam, with the northern branch becoming the Vettar River, and the southern branch continuing as the Vennar
• Northwest of Needamangalam, it splits again into three branches, with the Pamaniyar and Koraiyar Rivers originating from the southern branches, and the Vennar continuing through the northern branch

Arasalar River:

• River that flows through Tamil Nadu and Puducherry, and a distributary of the Kaveri River
• Splits into five different rivers when it enters Thanjavur district from Trichy
• Takes its course from Thiruvaiyaru of Thanjavur, branching from the Kaveri and emptying itself into the Bay of Bengal at Karaikal, east of Akalanganni
• Karaikal once served as a river port till the 19th century for yachts and Marakkalam ships of Karaikal Marakkayar for exports and imports
• The river is polluted by high concentrations of nitrate and chromium due to the mixing of sewage water into the river stream and industrial activities (as of 2013).

Floods in Cauvery Basin:

• The Cauvery basin has a fan-shaped distribution in Karnataka and a leaf-shaped distribution in Tamil Nadu
• Due to the shape of the basin, run-off does not drain off quickly, resulting in slower water flow and less occurrence of fast-rising floods in the basin.

Projects on Cauvery River:

• During the pre-plan period, several projects were completed in the Cauvery basin, including Krishnarajasagar in Karnataka, Mettur dam and Cauvery delta system in Tamil Nadu
• Lower Bhavani, Hemavati, Harangi, and Kabini are important projects completed during the plan period.

Industry in Cauvery Basin:

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

Cauvery River Disputes

• Tamil Nadu historically used about 602 TMC of the total yield of the Cauvery river, leaving only about 138 TMC for Karnataka until the turn of the 20th century.
• In 1924, Tamil Nadu built the Mettur dam across the Cauvery river.
• Subsequently, Karnataka and Tamil Nadu signed an agreement effective for 50 years.
• Tamil Nadu was allowed to expand its agricultural area by 11 lakh acres from the existing 16 lakh acres, while Karnataka was authorized to increase its irrigation area from 3 lakh acres to 10 lakh acres.
• The Cauvery River primarily served the needs of farmers in Tamil Nadu under this agreement.
• The agreement lapsed in 1974 and Karnataka claimed that it restricted its ability to develop farming activities in the Cauvery basin.
• Karnataka attempted to expand farming activities by building reservoirs, leading to the emergence of the Cauvery river water sharing issue.
• The water sharing dispute involves Tamil Nadu, Karnataka, Puducherry, and Kerala.
• The Cauvery Water Disputes Tribunal (CWDT) was formed in 1990 by Tamil Nadu’s demand.
• The CWDT adjudicated the dispute in 2007, but both Tamil Nadu and Karnataka challenged the tribunal’s order.
• The court reserved its order in September 2017.
• 

Major Inter-State River Disputes

River (s)	States
Ravi and Beas	Punjab, Haryana, Rajasthan
Narmada	Madhya Pradesh, Gujarat, Maharashtra, Rajasthan
Krishna	Maharashtra, Andhra Pradesh, Karnataka, Telangana
Vamsadhara	Andhra Pradesh & Odisha
Cauvery	Kerala, Karnataka, Tamil Nadu, and Puducherry
Godavari	Maharashtra, Andhra Pradesh, Karnataka, Madhya Pradesh, Odisha
Mahanadi	Chhattisgarh, Odisha
Mahadayi	Goa, Maharashtra, Karnataka
Periyar	Tamil Nadu, Kerala