Last week’s rains may have helped bring soaring summer temperatures down but they also served as a reminder to citizens of pothole-ridden roads and water-logging. Heavy rains over the last few years have been putting a lot of pressure on the already compromised storm-water drain network in the city. Promises from the Chief Minister that the problem will be addressed still remain unfulfilled.
After heavy rains caused lakes to overflow and many parts of the city, including the Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), were flooded, Chief Minister Basavaraj Bommai announced in November last year that a master plan for comprehensive development of the drain network would be drafted to address the problem of urban flooding.
Bruhat Bengaluru Mahanagara Palike’s Chief Commissioner Gaurav Gupta told The Hindu that the civic body had begun the work on the master plan and had floated a tender for the same. It is in the advanced stages of finalisation, he said.
“The master plan will not just be a comprehensive record of all storm-water drains, including so far unidentified drains, but will also highlight encroachments, locations where sewage is flowing into the drains, where sewage treatment plants can be established, catchment areas and the current carrying capacity of the drains. It will be a complete hydrological study of the existing drain network,” said a senior civic official.
Amidst growing public anger over the state of infrastructure in Bengaluru, the State Government had also announced ₹1,500 crore for taking up various drain related works, including strengthening of retaining walls, desilting and widening of drains. A senior civic official said that the short-term tender had been floated for the drafting of the master plan and had been opened around five days ago. The financial bid was being scrutinised and once completed, the tender would be sent to the State Government for approval.
Incidentally, the Comptroller and Auditor General (CAG), in its performance audit report on the management of storm water in Bengaluru Urban area (released September, 2021), had in fact pointed out that the BBMP did not possess fool-proof data on the total number/ length and nature of different types of drains under its jurisdiction.
“The absence of a comprehensive inventory of drains and their proper classification contributed to lack of clarity on critical issues such as the extent of buffer zone to be maintained, etc. This, in turn, hampered maintenance of drains as many utility lines like electrical, telephone, optical cable, etc., were laid across the drains in many locations obstructing flow in the drains,” the CAG noted, adding that BBMP had also failed to prepare an SWD manual specifying the design, construction and maintenance of the drain infrastructure of the city.
CAG also stated that BBMP had failed to factor in reasons for high-intensity rainfall due to rapid urbanisation, did not adhere to the provisions of Indian Road Congress and the guidelines of National Disaster Management Authority while designing and constructing roads/ drains, failed to prevent inflow of sewage, clear encroachments and blockages, and in general upkeep of the drains by taking up periodical inspections. All this has resulted in continuous misuse of the drains, the CAG said.
‘Sponge City’ concept
Agreeing with CAG’s views, Veena Srinivasan, hydrologist from ATREE, said cities across the world were looking at ways to drain out and hold water to prevent urban floods. Many cities in China and the U.S. have adopted the ‘Sponge City’ concept, as per which various measures are taken for urban surface water management.
“These are low-impact under which a city can be made porous so that there is room created for the rain. This, however, requires larger visioning and holistic, integrated planning,” she said. For instance, in Bengaluru, the lakes are full through the year due to either inflow of sewage or filled with treated sewage. “During the summer months, the levels can be brought down to make room for rain water,” she said.
Prof. M. Inayatulla, Director, Water Institute, University Visvesvaraya College of Engineering (UVCE), Bangalore University, concurred and said the need of the hour was a complete hydrological study of the drain network, especially run-off flow directions and how best to utilize it. “We lack an integrated watershed management approach and that must be the focus if we want to prevent urban flooding,” he added.
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