How did we reach this extreme point? How did the river dry up?
- Aarya Dhuttargi
- Mar 12, 2021
- 3 min read
In the past few decades, urbanization has become a massive deal-breaker for the government in terms of foreign investments, and the country’s economy. Bangalore, the I.T. Capital of India, massively contributes in the country’s total GDP. In 2014, Bangalore contributed US$ 45 billion, or 38 per cent of India's total IT exports. Huge isn’t it? With constant development, Bangalore is now one of the biggest cities in India. But is this the only side of development? Has development in Bangalore only given profits and benefits? The answer is a big fat ‘NO’. A coin has two side and so does development.
Civilizations were formed around the river banks which gradually used to expand and develop. But what would happen if the river itself dies in the process of development? The river of Arkavathy, originates from the Nandi hill ranges and riddles through a chain of lakes before touching the Hesaraghatta reservoir. From Hesaraghatta, the water flows till Thippagondanahalli (TG Halli) reservoir where it is joined by another stream-- Kumudvathi. From here, the river flows to join Cauvery. The river Arkavathy used to be the lifeline of the city of Bangalore. It receives annual rainfall of about 800mm. Catchment area for the city of Bangalore include, T.G. Halli reservoir, Hesarghatta reservoir and estimate of 617 tanks, all of these collectively have a storage of 143 Million cubic meters (MCM).
Shifting to groundwater
After 1970’s, groundwater water became accessible for farming through bore well technology. Through low cost and fast drilling technology, irrigation farming began to increase and open well or surface water irrigation decreased in the period of 1975. During the 1980s, farmers wildly began to be interested in eucalyptus plantation. Starting in 1970s, input to the TG Halli reservoir began to decline. The primary cause being groundwater extraction and eucalyptus plantation expansion. In 1981, the government of Karnataka, adopted the policy of low flat rate electricity tariffs, which allowed groundwater irrigation to increase.
On one hand, increase in water availability, changed the farmer’s choice of crop. From grain crops, farmers shifted to commercial farming like, horticultural crops, fruits, vegetables. Area expanded and farmers dug more and deeper bore wells. And on the other hand, the city expanded. The requirement of water supplies increased. From 1995 to 2005, the surface water flow has declined. Even thought the rainfall during these years was as usual, the reservoirs weren’t getting filled up. Bore wells were being dug up to 700-800 ft. suggesting that groundwater decline is partially responsible for surface water declines. Concerned about the declining flow, the government commissioned ISRO to study the problem. ISRO suggests that the areas around the Arkavathy and its channels and the reservoirs be divided into four zones with various zonal restrictions. It also recommended restrictions over Eucalyptus plantation and digging of bore wells.
Urbanization
In the past twenty years, a significant shift that is observed in the region was a slight decline in irrigated agriculture. But even then, there is no apparent decline in the extraction of groundwater. The number of wells and its depth continues to increase. This suggests that it isn’t the farmers requirement for irrigation that is decreasing the groundwater level but the increasing number of bore wells. To satisfy the water requirements of the city, countless bore wells were dug up resulting in depletion in ground water table. A large number of check dams were constructed to slow down the flow and to let the water penetrate. However, what urbanisation and the increasing concrete land between Hesarghatta and T.G. Halli has done is to only increase the run-off of rainwater. “Our studies have conclusively shown that the Arkavathy 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. Official 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. Multiple religious centers are coming up and also hundreds of demarcated walls, some near the river bank are being sold and we know that urbanization is not going to stop or slow- down.
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