Bengaluru has an advantage of having nearly 70 rainy days spread over the year.
However, Bengaluru drainage system (infrastructure) of 180 km long primary and
secondary storm water drainage system, can handle only 30 mm of rainfall in one
hour. So whenever there is a heavy down pour, the city faces problems. Lack of
open space has led to flooding low-lying areas during downpour. BBMP has listed
five main areas as flood prone and also identified 134 low-lying areas in Bengaluru,
prone to flooding. The East is most vulnerable with 108 areas, West has 31 areas
and Southern areas of Bengaluru are all prone to floods, while Northern parts of
Bengaluru are not an exception. A study by IISc has indicated that the fragile storm
water drain network in the 73 km
2 area between IISc and GKVK campus in Jakkur
has rainwater run-off exceeding the drain capacity. The reasons for flooding may be
attributed to excess flow into the conduits, silt deposition due to heavy flow of
water run-off and weakening of conduits or velocity of heavy run-off could damage
conduits, breaching them and flooding the areas. Changing the conduit width, slope
and roughness of material lining of the conduit considering conduit erosion and
deposition issues were possible solutions suggested (Gouri 2015).
The natural valleys are unable to pump out the excess rain and drain water. All the
valleys are choked with debris and heavily silted besides being encroached. In
August 2000, rains caused havoc in most areas of Bengaluru and BBMP had to
pump out one crore litres of water in the City market area. The operation went on for
three weeks. Since the water could not be drained out naturally, it had to be done
manually. Urban flooding is a new trend affecting Bengaluru, given its natural
gradient, the city did not face this problem earlier. The rainwater infiltration has
declined as the soil exposed to this purpose has gradually decreased over time.
Besides, the construction of tar/cement roads has increased leading to the decrease of
ground water table and the disappearance of open wells. This has resulted in flooding
of the city roads during heavy rainfall. The side drains and the shoulder drains filled
with mud and other garbage adds to the blocking of the natural water flow. The
low-lying areas in the city are prone to annual flooding due to overflowing of water
from the drains causing immense inconvenience to the residents.
The role of global economic players has played an important role in aspects like
utilization of land in specific. Bengaluru’s land prices have shot up immensely.
Some of the problems associated with urban land transactions include an unusual
escalation in the demand for urban property, creation of bogus documents, ‘benami’
and deceitful land transactions, coupled with insufficient checks/control at various
official levels for monitoring irregularities taking place. There is more than 500 % of
increase in the built up area of the city over the last 30 years, and there is some form
of violation of planning, building or land-related legislation. Demand on housing
with booming real estate has led to conversions of tank beds/major lakes into residential layouts. There are several examples of environmentally sensitive lands being
violated and not getting protected by the authorities. For instance, there are several
cases of urban conflicts in low-lying urban residential communities due to ineffective
urban planning in metro Bengaluru. For instance, an apartment complex of 300 plots
was built on the gradient of Shinivagulu Tank Bed in 1989 by the Bengaluru
Development Authority at Koramangala. A storm water drain of about 40 feet passes
454
S. Manasi and N. Jamwal
However, Bengaluru drainage system (infrastructure) of 180 km long primary and
secondary storm water drainage system, can handle only 30 mm of rainfall in one
hour. So whenever there is a heavy down pour, the city faces problems. Lack of
open space has led to flooding low-lying areas during downpour. BBMP has listed
five main areas as flood prone and also identified 134 low-lying areas in Bengaluru,
prone to flooding. The East is most vulnerable with 108 areas, West has 31 areas
and Southern areas of Bengaluru are all prone to floods, while Northern parts of
Bengaluru are not an exception. A study by IISc has indicated that the fragile storm
water drain network in the 73 km
2 area between IISc and GKVK campus in Jakkur
has rainwater run-off exceeding the drain capacity. The reasons for flooding may be
attributed to excess flow into the conduits, silt deposition due to heavy flow of
water run-off and weakening of conduits or velocity of heavy run-off could damage
conduits, breaching them and flooding the areas. Changing the conduit width, slope
and roughness of material lining of the conduit considering conduit erosion and
deposition issues were possible solutions suggested (Gouri 2015).
The natural valleys are unable to pump out the excess rain and drain water. All the
valleys are choked with debris and heavily silted besides being encroached. In
August 2000, rains caused havoc in most areas of Bengaluru and BBMP had to
pump out one crore litres of water in the City market area. The operation went on for
three weeks. Since the water could not be drained out naturally, it had to be done
manually. Urban flooding is a new trend affecting Bengaluru, given its natural
gradient, the city did not face this problem earlier. The rainwater infiltration has
declined as the soil exposed to this purpose has gradually decreased over time.
Besides, the construction of tar/cement roads has increased leading to the decrease of
ground water table and the disappearance of open wells. This has resulted in flooding
of the city roads during heavy rainfall. The side drains and the shoulder drains filled
with mud and other garbage adds to the blocking of the natural water flow. The
low-lying areas in the city are prone to annual flooding due to overflowing of water
from the drains causing immense inconvenience to the residents.
The role of global economic players has played an important role in aspects like
utilization of land in specific. Bengaluru’s land prices have shot up immensely.
Some of the problems associated with urban land transactions include an unusual
escalation in the demand for urban property, creation of bogus documents, ‘benami’
and deceitful land transactions, coupled with insufficient checks/control at various
official levels for monitoring irregularities taking place. There is more than 500 % of
increase in the built up area of the city over the last 30 years, and there is some form
of violation of planning, building or land-related legislation. Demand on housing
with booming real estate has led to conversions of tank beds/major lakes into residential layouts. There are several examples of environmentally sensitive lands being
violated and not getting protected by the authorities. For instance, there are several
cases of urban conflicts in low-lying urban residential communities due to ineffective
urban planning in metro Bengaluru. For instance, an apartment complex of 300 plots
was built on the gradient of Shinivagulu Tank Bed in 1989 by the Bengaluru
Development Authority at Koramangala. A storm water drain of about 40 feet passes
454
S. Manasi and N. Jamwal