Will Cauvery quench the thirst of Bangalore?
The ambitious Cauvery Stage IV Phase II project augmenting water supply to Bangalore at a cost of Rs 1759 crores will be commissioned today. It is time to retrospect into the water supply arrangements for the city of Bangalore in the last two centuries and also realise how Bangalore has become critically dependent on Cauvery River, and how we are running out of options for water resources to meet the growing needs of Bangalore Metropolitan region.
More than 95 per cent of water supplied to the city is from the Cauvery. Efforts have been made in the last few decades to identify fresh water resources to meet the demands of this fast growing metropolis. But time has come to look at radically new solutions to meet the insatiable thirst of this great city.
Looking back into the 19th century, Bangalore then, a small town depended for a long time for its water supply on private and public dug wells including Kalyanis or stepped wells and also on a series of tanks in the city. The Committee of elders formed by the Maharaja in 1862 to look after the welfare of the citizens of the town arranged to supply water through channels from Dharmambudhi, Sampangi, Sankey tanks etc.
Hessarghatta water source
As Bangalore population crossed one lakh mark in 1881, K. Seshadri Iyer, Dewan of Mysore, gave a serious thought in 1882 to provide safe drinking water to Bangalore. He persuaded the British and the Maharaja to agree to provide drinking water to Bangalore including the requirements of the military.
After investigations, it was decided to construct a reservoir at Hesaraghatta across River Arkavathi, a tributary of River Cauvery with a storage capacity of 900 cubic feet for three years supply. The water was carried through an open channel by gravity up to Soledevanahalli and from there pumped by steam driven pumps to the City through a 15” CI Main up to the Combined Jewel Filters (CJF) near 18th Cross, Malleswaram, where it was filtered and connected to the distribution system.
The military authorities were allowed to draw water from the open channel at Tarabanahalli for their treatment plant and pump the water to supply to the military establishments in the city. This first potable water supply scheme to Bangalore was commissioned on 7th August 1896. The cost of the project was Rs 19 lakhs and the scheme was called Chamarajendra Water Works.
Though the Hessarghatta water source was not reliable, improvements were made to prevent wastages and enhance supplies to the city. The leaking masonry channel was replaced by a 35 MLD (million litres per day) capacity 42” (1050 mm) diameter concrete hume-pipe duct. A second pumping main of 15“ (375 mm) size was laid in 1948 with additional pumps to increase supply to Bangalore by 9 MLD.
As number of industries like BEL, HMT etc. were developed along the alignment, a third 15“ (375 mm) pumping main was laid in 1958 up to HMT crossing to supply 4.5 MLD of water to the en-route industries augmenting the 9 MLD to the city from other two mains. Because of urbanisation in the catchment area, inflow into Hessarghatta lake reduced drastically in the past two decades and it is now zero. No water is drawn to the city from Hessarghatta now.
Due to great plague, Bangalore population came down from 1,80,366 to 1,59,000 between 1891 and 1901. Supply of water to Bangalore was therefore, comfortable till 1916. In 1922, Hesaraghatta Reservoir dried up for almost an year due to severe drought. This forced the Government to form a Committee on 1st May, 1926, under the Chairmanship of Sir M. Visvesvaraya to investigate and suggest a permanent and satisfactory scheme for Bangalore.
The Committee gave its final report to Government in 1928, and recommended that permanent relief to Bangalore will be to draw water from the Cauvery river, although the capital cost and cost of maintenance would be high. An estimate of Rs 1,000 lakh for bringing 100 MLD Cauvery water to the City was prepared. However, as the cost of implementation was very high, the committee proposed construction of another reservoir at Thippagondanahalli, downstream of Hesaraghatta at the confluence of Arkavathi and Kumudhwathi rivers for immediate improvement of the water supply scheme at lesser cost.
The Chamarajasagar Dam Scheme, popularly known as Tippagondanahalli Dam was planned, with the construction of a masonry reservoir and a capacity of 3038 cubic feet, but restricting the height in the first stage for storage of 1072 cubic feet. Treatment works to be located below the dam and laying a 24” (600 mm) cast iron main to supply 6 million gallons per day of water to the city, catering to a population of 3 lakhs. The cost of the project was `55 lakh and it was taken up and commissioned on 15th March, 1933.
The first supply of water to the city from the Tippagondanahalli source was 27 MLD. During 1954-1958, the height of the dam was raised to increase the storage to 1824 cubic feet and draw another 45 MLD of water to the city through a new 675 mm pumping main.
During 1961-63, the storage in the lake was further raised to 3038 million cubic feet by providing crest gates on the waste weir of the reservoir and the water supplies to the city was augmented by another 72 MLD through a 900 cast iron main. In the next two decades, the inflow into the reservoir came down significantly, and at present, only about 30 MLD of water is drawn to Bangalore. The catchment area of Thippagondanahalli source is severely threatened by change of land use pattern, inconsistent rainfall and intensive groundwater irrigation and blocking of secondary and tertiary nallahs or valleys.
Cauvery water supply schemes
As Bangalore became one of the prominent cities of India in the post independence era, a number of public sector industries were established here. As the city grew, so did its population. In the last three decades, the population has exponentially increased, and so did the demand for water. Finding out alternative sources of water became necessary.
An expert committee constituted by the government in 1958 examined four alternative water sources Cauvery, Arkavathi, Hemavathi and Shimsha and recommended Cauvery water source as the best suited and dependable source for the growing needs of Bangalore as recommended by Sir M. Visvesvaraya, way back in 1928. Hence, Cauvery River that flows nearly 120 kms away and a level that is 1000 feet below the altitude of Bangalore was identified as a reliable source and has been developed in stages, from time to time, to meet the increasing water demands of this city.
Cauvery from Shiva Anicut
The Karnataka Government, heeding to the reports of the committee, accorded administrative sanction for implementation of Cauvery Water Supply Project in 1964. The government decided to bring water from Cauvery to Bangalore and to implement this project, established the Bangalore Water Supply and Sewerage Board (BWSSB) during September 1964.
The first stage Cauvery water supply project to draw 135 MLD of water to the city was executed at a cost of `35 crore, and was commissioned in 1974. This was followed up by executing the second stage project at a cost of `80 crore to drawn an additional 135 MLD of water to the city, which was commissioned in 1982. The third stage project was taken up at a cost of Rs 240 crore, which brought an additional 270 MLD of water to the city from 1992 onwards.
The first phase of the IV stage of the project executed at a cost of Rs 1319 crore was commissioned in June 2002, bringing another 270 MLD of water to the city. The II Phase of the IV stage project is designed to bring another 500 MLD of water to the city and will be officially commissioned today by the Chief Minister of Karnataka.
Cauvery Scheme, Stage-IV, Phase-II
The Cauvery Water Supply Scheme Stage-IV, Phase-II was taken up in order to meet the ever increasing demands of Bangalore city particularly in the erstwhile CMCs/TMC which was merged into Greater Bangalore (BBMP) in 2007. This project was taken up by the BWSSB to augment water supply to the city by 500 MLD at the cost of Rs 1759 crore with funding from Japan International Cooperation Agency (JICA) (85%), Government of Karnataka (7.5%) and Bangalore Water Supply and Sewerage Board (7.5%).
This project work commenced in December 2009 and was completed only this month. The raw water, for this project, is abstracted from River Cauvery at Shiva Anicut and conveyed through an open canal of 2 kms to Shiva Balancing Reservoir (SBR). From here, the water is conveyed to a water treatment plant at Thorekadanahalli (TK Halli) through a combination of 700 m canal and then gravity pipeline of 3000 mm diameter of 6.3 km long steel pipeline upto Netkal Balancing Reservoir (NBR) and from there through 2600 mm diameter of 9.8 km long steel pipeline.
Raw water is treated in a water treatment plant of capacity 500 MLD at TK Halli. Treated water is conveyed to Bangalore through 2.7 m diameter steel transmission main of 70 km long with pumping stations at T.K Halli, Harohalli and Tataguni. Each pumping station has 10 pumps (6 working and 4 standby) each of 3100 HP capacity motors.
The transmission main branches into two one towards East andthe other towards West at Vajarahalli before entering Bangalore. One branch carries water to reservoir on east and north of Bangalore and the other branch, conveys water to a reservoir on west and north of Bangalore. The total length of mainline within city is 84 km of various diameters from 2200 mm to 600 mm.
Clear water trunk mains feed water to 7 Ground Level reservoirs of total capacity 152 ML constructed at Jambu savaridinne, Kudlu, Uttarahalli, GKVK, OMBR, Hoodi and Narayanapura and also the existing reservoir at Hegganahalli. This project will benefit mainly people staying in Yelahanka, Byatarayanapura, Bommannahalli, Mahadevapura, K R Puram and Rajarajeshwari Nagar and Kengeri areas.
Cauvery allocation to Bangalore
The total drawal of water from the River Cauvery to the city at present is 810 MLD and, this will increase to 1310 MLD after completion of the II phase. The water allocated to Bangalore from the Cauvery river will be completely used after completion of the II phase.
Though the BWSSB is executing capacity augmentation projects one after the other, it has not been possible to meet the ever increasing demands of a city that has been growing relentlessly. Additional sources are also limited. Therefore, in the future, the water supply needs of Bangalore would have to be met out of non-conventional means.
Big projects of supply augmentation would have to give way to water conservation measures, and also by greater adoption of rain water harvesting systems. Proper pricing of water is also necessary to promote efficient use, and to meet increased costs. Recycling and re-use of used water for meeting the flushing, landscaping and gardening needs has to be made mandatory.
Industrial, construction and agriculture needs will have to be met by reclaimed water. BWSSB alone cannot do this. This calls for increased cooperation and collaboration of all the city planners, builders and the citizens. Else gloomy days of water scarcity, many times witnessed in the past, will once again surface to dog the quality of life in this great city.