Why Bangalore goes 6 feet under

Why Bangalore goes 6 feet under


Children fishing in the Ulsoor Lake.
Monica JhaFirst Published : 17 Jun 2009 07:36:09 AM ISTLast Updated : 17 Jun 2009 09:32:35 AM IST
BANGALORE: One hour of proper rain and the roads get flooded, traffic comes to a standstill and drains start overflowing.
Why is Bangalore always flooded? Experts on ecology and meteorology suggest that Bangalore floods are ‘human- induced’ and not due to a major change in the rainfall pattern. Damage of the natural drain network, reduced water-storage capacity, and unplanned urbanisation are proving to be the city’s undoing.
Faulty nature
The primary reason for frequent flooding in the catchment are alteration in landscape topography and change in land use (rampant unplanned developmental activities in the catchment).
Bangalore has six major lake series- Yellammappa Chetty, Madavara, Puttennahalli, Byramangala, Hulimavu and Varthur. Earlier, with all the lakes alive and connected to each other, excess water from one lake used to flow to the other till it reached a lake that was connected to a river.
These rivers get emptied into the natural drainage network, the four major natural valleys, Vrishabhavathi, Koramangala, Challaghatta and Hebbal. Rain water naturally flows from the higher to the lower level until there is an obstruction in the way. While water from Hebbal and KC valleys meet North and South Pennar River in Tamil Nadu, water from the Vrishabhavathi Valley joins the Cauvery River in Kanankapura. Currently, however, many residential layouts have been formed in the lake beds. After rains, these areas get flooded because these areas are meant to collect the rain-water. Of late, with the increasing pressures on land in the municipal limits, the land belonging to the lake-beds has also been subjected to ad-hoc development approaches and the functional ability of the ecosystem is impaired.
No place to store
Wetlands (lakes, tanks, water bodies) have the capacity to retain excess floodwater during heavy rainfall that would otherwise cause flooding. With several lakes being dead or misused or with much-reduced capacity, the water-holding capacity of the city has dropped significantly. There is no mechanism for the storm water to drain and so the surrounding areas get flooded.
There is a way out of this mess. Experts suggest that storing natural drainage network by linking of lakes and clearing encroachment on lakes and increasing their capacity.
What has the government done?
● Following the Lakshman Rau Committee Report on lakes and tanks, a government order (GO HUD 794 TTP 85) on December 31, 1985 was issued that no layouts in lake or tank beds should be allowed to be formed by BDA or any other agency.
● BBMP in its annual budget every year makes provision for improvement of storm water drains (SWD).
● Desilting of drains was taken up in June-July 2000, based on a report submitted by former consultant to the BBMP, G Aswatha Narayana, who was appointed to conduct a study on SWD, following a direction from the High Court 1999.
● In 2003, SWD remodelling project was taken up at a cost of Rs 180 cr (escalated to Rs 643 crore).
● In 2006, BBMP gave a contract to STUP consultants for remodelling of SWDs- all the four valleys (228 km)- at a cost of Rs 425 crore.
● The state government had recently proposed to upgrade 850 km SWD at a cost of Rs 4,000 crore. A detailed project report is being made for this which is expected to be submitted in two years.
● On June 14, 2009, Chief Minister BS Yeddyurappa formed a monsoon management task force. Ministers ordered removal of encroachment on SWDs.
All in the budget
● Problems of the flood- prone areas such as Puttenahalli, Nayandahalli, Silk Board Junction, Bhadrappa Layout, Victoria Layout, Kamakya theatre, Bandeppa Colony, Arakere Layout, Airport Road flyover junction, MES area have been addressed this year.
● To provide basic amenities to the newly added areas DPRs have been prepared for construction/remodeling of SWD network to be submitted to the Centre shortly for funding under the JNNURM.
● The on-going work in the four major valleys will be expedited during this financial year.
● At Puttenahalli and Chunchaghatta, a road over the storm water drains has been proposed.
Based on inputs from: A Muthuchami, director, Meteorological Department, Bangalore, Dr TV Ramachandra, Centre for Ecological Sciences, IISc and his papers- Status of wetlands in Bangalore and its conservation, and Environment Impact of Development Activities in the Bellandur Catchment Areas G Aswatha Narayana, former consultant to BDA, BBMP and the World Bank
Urban legend
The case of South Bangalore is typical. As this part of the city shows a typical combination of all the factors mentioned above. This area falls under the Koramangala- Challaghatta valley, in which the natural flow of storm water is obstructed due to man-made structures. The 280-sq-km-catchment area comprises Puttenhalli, Varthur and Hulimavu chains of lakes and includes 22 tanks. However, most of these lakes have reduced capacity due to encroachment and pollution.
Unplanned urbanisation is also heavy in this area. And so this area is worst-affected during monsoon. Areas like Gandhinagar, JP Nagar, Jayanagar, Lakkasandra, BTM Layout, Madiwala, Koramangala, Airport, Shanthinagar, Richmond Town, Sampangiramnagar, Shivajinagar, Ulsoor and Devarajeevanahalli fall in this catchment area. Water from the Bellandur tank is supposed to flow to Varthur lake and ultimately join the Pennar river. However, according to a report by the Centre for Ecological Sciences, IISc, the land use changes in this area have resulted in loss of natural drainage networks. The alteration of landscape topography has resulted in the storm water to take a new course, which passes through residential areas, the report says.
Moreover, several lakes like Agara, Begur, Arakere, Madiwala and Puttenahalli have reduced capacities. These lakes overflow and cause flood situation in areas like Bannerghatta Road, Madiwala, Ejipura, Koramangala and JP Nagar.