Experts have identified various other water sources for Bangalore, as the Cauvery supply cannot be stretched any longer.

Bangalore’s march to a megalopolis is unstoppable. Search is on for more water sources for its daily needs in all earnestness. The city’s population currently stands at around 10 million and a daily supply of 960 million litres a day (MLD) of water sustains these souls. With borewells yielding another 570 MLD, a major portion of the precious liquid comes from Cauvery river. Perched over a ridge on the Deccan plateau, Bangalore is unique in the sense that water has to be brought over long distances by using booster pumps, thereby requiring considerable expense on power for the purpose.

The expert committee headed by B.N. Thyagaraja, former chief of the BWSSB, which went looking for water sources as far as Kodagu and Shimoga districts and assessing the hassles the topography and the neighbouring States might pose in tapping water from them, has laid several options on the table for the Government to consider. It has become imperative for the authorities to decide upon some of these options and set the work in motion.

It is clear enough that the city cannot bank upon the Cauvery any more for quenching its rising thirst as it has almost exhausted its share under the Karnataka’s allocated 270 tmc ft. of water as per the 2007 Cauvery Tribunal Award. Meanwhile, the city’s population is ever on the increase and may well cross 14.2 million by 2021, requiring 1460 MLD of water.

To begin with, the expert committee has identified two streams, Kakkattuhole and Konganahole in Kodagu district, to bring 10 tmc ft. of water into the Cauvery basin. The two streams are major tributaries of the Barapole, a west flowing river which runs to Kerala before draining into the Arabian Sea. According to Mr. Thyagaraja, from the confluence point, 7 to 10 tmc ft. of water can be diverted to Lakshmanathirtha, a tributary of the Cauvery, by cutting a small ridge. The proposal, if taken up, will require Rs. 100 crore of investment and the work can be completed in two years. The project can however attract resistance from the local people and there may be some objection from Kerala. The latter can be easily overcome as the river is a west flowing river and has copious supplies.

Storage reservoirs

A second proposal relates to creation of three storage reservoirs at Mekedatu, before the Cauvery enters Tamil Nadu. It is based on the surmise that in one out of four years, excess rainfall owing to copious monsoons results in Cauvery carrying surplus water which may be diverted to the reservoirs at Mekedatu. The committee drew support from the 30-year data of the rainfall and flows into the Cauvery. This, the committee felt, should have no bearing on the Tribunal Award, as only the water in excess of Tamil Nadu’s quota would be drawn for the storage. However, Tamil Nadu has already raised objection against the proposal and Chief Minister Jayalalithaa has held it ‘wholly illegal’. The Karnataka proposal envisages hydropower generation at Mekedatu but disallows irrigation.

Progress is already in sight on the Yettinahole Project envisaging lifting of 24 tmc ft. from the Nethravathi, again a west flowing river which has a total yield of 2,000 tmc ft. of water. Last December (2013) the State Government announced commencement of the project by calling tenders for barrages across eight streams that feed the river. The Rs. 8,000 crore project proposes lifting the water to a height of 150 metres in Sakleshpur taluk of Hassan district. It would then be carried over a distance of 288 km through a gravity channel to fill up Tippagondanahalli and Hesaraghatta tank from where the pipelines to take them to Bangalore already exist. On the way some water will be apportioned among Hassan, Tumkur, Ramanagaram and Chikkaballapur districts. Only around 300 hectares of forest land is being acquired for the project and the Forest Department is being given alternative land for the purpose. It has been cleared by the Union Ministry of Environment and Forests.

Most viable

Of the nine proposals, the most viable seems to be the one that envisages drawing 30 tmc ft. of water from Linganamakki reservoir on Sharavathi river in Shimoga district. It is considered the safest as the river is a west flowing one and flows to the Arabian Sea within the State. Mr. Thyagaraja says the reservoir has a maximum storage capacity of around 181 tmc ft. of water and could be the most sustainable source of supply to Bangalore as it is mostly used for generation of 5,724 million units of power annually and not for agricultural purposes. It envisages pumping water to Mani reservoir and then pumping it to Yagachi reservoir in Hassan district. From there it can flow through a gravity channel to Bangalore over a distance of 130 km.

The project estimates that for every 10 tmc ft. of water to be pumped, the power generation losses would be to the tune of 350 million units which is quite negligible when compared to the benefits accruing to the city. With the gas-fed power plant at Bidadi having been commissioned, the losses could be more than offset, it is stated. However, the capital cost for the project is computed at Rs. 12,500 crore. In the committee’s view this is the most economical of all the proposals as it taps the water of a west flowing river, brings pure water, and does not involve hassles with other States. In view of the high cost, the expert committee has suggested that a high power committee be set up to assess the feasibility of the project.

Other proposals for water for Bangalore include cutting down the dependence on fresh water by treating the waste water and supplying it for reuse. Mr. Thyagaraja says, normally an individual requires 150 litres of water a day. Of this, only a third is needed for drinking, bathing and cooking. By laying a dual pipeline network, the recycled water could be used for the other two-thirds of the needs such as washing, flushing, mopping, gardening, car-washing and other non-potable purposes. He says this could be immediately introduced for new layouts and may require amendment in byelaws. The proposals also call for regeneration of Hesarghatta and T.G. Halli and Arkavathi valley by bringing them into the ‘Green Belt’.

Other plans

The committee also recommended remodelling of the stormwater drains in the city, revival of all lakes and creation of additional lakes and ensuring that no sewage seeps underground. Mr. Thyagaraja says the city (groundwater being extracted by borewells) is actually engaged in ‘mining of heritage water’ that had accumulated for thousands of years in the stony layers of the ground. The city fathers should take care to replenish the ground water by opting for measures such as tertiary level treatment of at least 30 per cent of sewage and allowing it to flow to lakes for seeping underground. It has also advised plugging of leaks which allows 48 per cent of the city water supply to remain unaccounted, either due to leaks or absence of metering.

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Note: Water received in reservoirs is measured in tmc ft. (thousand million cubic feet) and water supplied is measured in MLD (million litres a day).