Karnataka

Despite rain, where is river Arkavathi?

The multiple hills of Chickballapur tower over the landscape where a series of tanks, named after nondescript villages, mark the formation of Arkavathi river. Less than 20 km ahead, the clear water gives way to thick sludge flowing between concrete layouts.

The Hindu’s check on the river, from its origin in the relatively-pristine Nandi Hills to the cesspool at Tippagondanahalli reservoir, showed a waterbody that seems not to have benefited from the rain.

Currently, the city has seen over 800 mm of rainfall, while Bengaluru urban and rural districts have seen between 20% and 44% “excess” rainfall so far. But while reservoirs and tanks have filled up, the river itself seems to have disappeared.

Despite rain, where is river Arkavathi?
 

‘Clean’ Arkavathi

In the foothills of Channarayaswamy Betta, the Chikkagowdana lake — the first tank in the path of the Arkavathi — is more than half full. A little further down, the series of small lakes that signify the formation of the river, too, have water levels unseen in over two decades.

“Till 25 years ago, these lakes would be filled regularly. But in the past two decades, the lakes have barely filled up,” says Muni Yellappa, a farmer whose 15-acre cultivable land is beside Rajghatta lake, the fourth in the series of tanks. “But this year, the rain has seen it rise to the best levels in over two decades,” he said.

Similarly, Dodda Tumakuru lake near Doddaballapur has filled up after more than 15 years, while filling up of large swathes of Kokalu and Byatha lakes where overgrown shrubs and trees that thrived on dry tankbeds over the years are now submerged. These feed into Hessarghatta lake, which after years, is seeing water level reach 5.1 ft.

Chikkagowdana kere

Chikkagowdana kere  

 

However, what is apparent is that the stream that snakes through paddy, eucalyptus, vegetable and flower fields remains dry. “The river has dried up because of agriculture-related activities. Check-dams to divert water to the field, eucalyptus plantations (273sq. km of them in the catchment area) and sinking of borewells has impacted groundwater,” says Sharathchandra Lele of Ashoka Trust for Research in Ecology and the Environment (ATREE).

Now, the cesspool

It is after Hessarghatta lake that the river dramatically changes, so does the landscape where agricultural fields give way to upcoming layouts. At Tarabanahalli, where residents saw the Arkavathi briefly swell during heavy rain last week, the river is reduced to stagnating puddles of murky water. At National Highway 48, some 5 km from Hessarghatta, the river is in the form of rapidly-gushing raw sewage, much of it coming from industries in Peenya and Nelamangala.

This flowing sewage ends up at Tippagondanahalli reservoir, where for the first time since 2010, the water level has gone up to 55 ft, said officials there. It last reached full capacity of 72 ft only in 1983. The water is still too polluted to even think of pumping as drinking water, said a Bangalore Water Supply and Sewerage Board official there.

Despite rain, where is river Arkavathi?
 

However, what urbanisation and the increasing concrete between Hessarghatta and T.G. Halli has done is to increase run-off of rainwater and also increase sewage flow. “Our studies have conclusively shown that the Arkavathi drying up is not linked to rainfall. Due to urbanisation, you will see water gushing into rivulets and flowing out without seeping into the ground,” says Veena Srinivasan from ATREE.

This is seen in the experience of Sommana, a resident of Kammasamudra, where sprawling layouts are planned. “On days that it poured, the river swelled with reddish, mucky water. Within a half hour, it had returned to a thin stream of sewage,” he said.

Continued encroachments

Without rampant urbanisation, researchers believe with high rainfall, tanks would have been filled and groundwater saturation would have seen surface flow in monsoon. Now, the ‘river’ has dried up within a few days of rain — pointing to encroachments, blocking of channels and increased concretisation.

Officials of Cauvery Neeravari Nigam Ltd., which has been entrusted with the rejuvenation of the river, say encroachments had been identified along 70 km of the bank. But, they admitted, a few encroachments have been removed.

Despite rain, where is river Arkavathi?
 

At Kammasandra, multiple religious centres have already come up, while hundreds of demarcated plots, some even by the banks of the river, are being sold by the day. “Plots further away from the river are being sold for ₹750 per sq. ft; while, closer to the river, they are selling it for ₹600 per sq. ft. Though developers insist that the documents are fine, we know there could be encroachment,” said Lingaraju, a resident of Hosakerehalli, who is looking to buy a plot in the area.

Purifying the river

Recognising that Arkavathi is mutilated by the sewage pouring from the city, the Bangalore Water Supply and Sewerage Board (BWSSB) is attempting to use Israeli technology to form a “natural biological system” near Tumakuru Road that will purify the river.

The ₹10-crore project, which will involve aerator systems to increase dissolved oxygen and series of plants that removes pollutants, hopes to reduce inflow of sewage into T.G. Halli. “Israeli experts have told us with the system, the water in the streams will be purified by up to 80%,” said a senior BWSSB official.

Despite rain, where is river Arkavathi?
 

While tenders have been called for the fourth time, officials admitted that executing the project is “difficult”. “This system has not been done in India, and so far no company has been eligible according to our tender rules,” said the official.


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Printable version | Jun 10, 2021 5:26:11 AM | https://www.thehindu.com/news/national/karnataka/despite-rain-where-is-the-arkavathi/article19711198.ece

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