Why can’t Bangalore’s lakes take it anymore?

Why can’t Bangalore’s lakes take it anymore?

Deepa Kurup and Divya Gandhi
A city creaking under unplanned growth becomes vulnerable to flooding as lakes and storm water drains lose inter-linkages
Most of the inundated areas are close to tank beds and catchments

313 acres of lakes and tank area has been encroached upon

— Photo: K. Murali Kumar

Poor infrastructure: Traffic was disrupted for more than three hours on Tuesday on Mysore Road in Bangalore after the Nayandahalli Lake overflowed.
BANGALORE: Images of residents wading through waist-deep water, vehicles stranded on choked arterial roads and civic authorities in a flap over the sudden deluge have been all too familiar over the past week. New areas have begun to throw up an old problem as the city engulfs its outskirts: urban flooding.

Even as authorities claim that nothing could have prepared the city for the unusually heavy rain — July rain was a 60-year high and August was a 10-year record — urban planners and scientists point out that flooding is but an inevitable consequence of unplanned development that has disturbed the natural hydrology of the city, and in particular, the health of its lakes.

Bunded, encroached and converted into veritable dumpsites of the city’s waste, our lakes, which were constructed centuries ago with the vision to store rainwater, recharge groundwater and thereby reduce runoff, are choking. It is no surprise, therefore, that most of the inundated areas are those that are close — if not built on — to tank beds and catchments: last week eight tanks in northeast Bangalore overflowed as did the two natural drainage channels that connect them. While one of the channels connects Bettahalasuru, Yelahanka, Agrahara, Rachenahalli, Jakkur and Amruthahalli tanks, the second flows between Hebbal and Nagavara tanks. Odeyarapalya and several areas near Hennur Bande were submerged as water levels rose up to as much as five feet. Authorities may be hesitant to term these layouts “unauthorised,” but the fact remains that several of these “lakefront” layouts obstruct the natural flow of water. BBMP Joint Commissioner (Byatarayanapura) Virupaksha Mysore said that these low-lying layouts were agricultural fields which were developed much before these areas came under the corporation.

Encroachment
According to A.T. Ramaswamy’s second interim report, 313 acres of lakes and tank area have been encroached upon. A comparison of 1930 Survey Department maps and 2005 satellite maps of ISRO show that 15 to 20 per cent of tank bed land has been encroached.

To complicate matters, the storm water drains, which pour into tanks, have become repositories of sewage and silt has to be removed from them. Residents of Odeyarapalya complain that some drains have been “under construction” for years now. Damodar Reddy, a resident of Chellekere, said: “This problem dates back nearly two decades. There are not enough drains or vents; and what we have is not being maintained.”

Although north Bangalore was worst affected this time, the situation is not very different elsewhere in the city. Iqbal Ahmed, a resident of HBR layout, found his house flooded on Sunday. And the reasons are the same. Silt has not been removed from both the storm water drain and the Kachakaranahalli Lake near his house in the past 10 years, he says.

BBMP Chief Engineer (Storm Water Drains) said that encroachments on the storm water drains obstructed the water from reaching the lake.

A study conducted on the pattern of urban sprawl pattern in Bangalore by T. V. Ramachandra and Uttam Kumar of the Indian Institute of Science in 2007 has startlingly revealed that the number of water bodies in the city has declined by more than 60 per cent between 1973 and 2007.

‘Source control’
“As the city gets more built up, the runoff increases from 10 to 90 per cent,” said Vishwanath S. of the Rainwater Club. “We need ‘source control’ — that is, harvesting rainwater and storing it or using it to recharging groundwater — to bring the runoff back to 10 per cent.”

“Urban flooding in Bangalore, unlike what we see in Patna and New Delhi, is a very local phenomenon. Flooding here is not triggered by rivers breaching their banks miles upstream, but is a direct result of rain over the city itself. And so the solution for flooding has to be local. Every builder, developer and individual owner should be held accountable for the runoff they produce,” he said.

Mr. Vishwanath added that what Bangalore needs is a “water use plan” — just as there is a land use plan — for groundwater, storm water, piped and waste water.