URBAN FLOODS –A RELATIONSHIP BETWEEN DISASTER AND DEVELOPMENT:
CHENNAI FLOODS 2015
Chennai, State capital of Tamil Nadu lies in the
Eastern Coast of South India where three watercourses through it namely, Cooum
River, Adyar River and Buckingham Canal. Chennai is the fourth largest
Metropolitan in India.
OF CHENNAI CITY
Chennai, having a plain terrain is bounded by Bay of
Bengal in the East with an average elevation 6.7m from the mean sea level.
Chennai experiences most of its rainfall during October to December. Average
annual rainfall is about 1200 mm – 1300 mm being situated on the coastal side.
Figure 11.2 Growth of Chennai City
Source: Chennai Municipal
OF CHENNAI FLOODS:
Chennai frequently experiences flooding due to heavy rains (October-December).
Of which few catastrophic floods during 1976, 1985, 1996, 1998, 2005, 2008,
2010 and 2015 caused heavy damages. Rainfall was 142mm in 27.10.2005. Rainfall
was 235 mm in 2015 only during October – December period.
OF CHENNAI FLOODS:
RELATIONSHIP BETWEEN DISASTER AND DEVELOPMENT:
graphic shows the various “orientations” with which you may analyze the “field”
of development and disaster vulnerability. The field is divided into positive
and negative aspects of the disaster/ development relationship by the vertical
axis. The right half reflects the positive or optimistic side of the
relationship and the left side of the diagram deals with the negative aspects
of the relationship. The short statement given in each quadrant sums up the
basic concept derived from the overlap of the two realms.
Disasters setback development programming destroying years of development
transport and utility systems are destroyed by a flood.
Rebuilding after a disaster provides significant opportunities to initiate
self-help housing program to rebuild housing destroyed by an earthquake teaches
new skills, strengthens community pride and leadership and retains development
dollars that otherwise would be exported to large construction companies.
Development programs can increase an area’s susceptibility to disasters.
major increase in livestock development leads to overgrazing, which contributes
to desertification and increases vulnerability to famine.
Development programs can be designed to decrease the susceptibility to
disasters and their negative consequences.
projects constructed under building codes designed to withstand high winds
result in less destruction during the next tropical storm.
Urbanization: Chennai – the capital city of Tamil Nadu is also linked with
numerous economic prospects & the facilities also. Chennai has a large migrant
population which accounts to 28% of Chennai’s population in 2011. Due to this,
the encroachment of all water bodies as slums & for the development of
urban infrastructure reduces the rain water carriage capacity of the few
existing water ways. Development of transportation facilities like MRTS all
along the water ways in some areas and subsequent developments of that also
aggravates the flood risks of Chennai in addition to health risks
URBAN LANDUSE CHANGES, GOVERNANCE AND FLOODS:
of increased flooding in Chennai are identified as:
urban sprawl and loss of natural drainage. Inadequacy of storm water drainage
system and lack of maintenance. Increase in impervious surfaces. Paving of
roadsides, park and open areas causing flood severity. Many of the water
bodies including man-made wetlands/lakes and natural depressions and have
disappeared due to waste and development or slum encroachments .Lack of
coordination between agencies.
11.5 Land Cover
worst rainfall to have hit the Capital of Tamilnadu in past 11 years . Building
new Flats, Houses by cutting trees , destroying riverbed’s , natural ponds,
poor water drainage systems have at last showed how dangerous it was for the
place. Till now in the 24 hours gap Chennai received 246.5 mm rainfall, which
was very huge. It was in November 1976 when Chennai was thundered by rainfalls
and a record of 452.4 mm was received. In 2015 with rain of 246.5 mm itself it
has caused lot of damage. So it is unimaginable to know what will happen if
history of 1976 repeats.
The Nungambakkam rain gauge recorded 270 mm on October 27, 2005;
280 mm in 1969, and 450 mm in November 1976. 235 mm in2015. Even in 1976, Adyar
overflowed its banks and invaded first-floor houses., Chennai has a host of
expensive infrastructure ,a brand-new airport built on the floodplains of the
River Adyar. A sprawling bus terminal in flood-prone Koyambedu
Transit System constructed almost wholly over the Buckingham Canal and the
Pallikaranai marshlands .Expressways and bypass roads constructed with no mind
to the tendency of water to flow. An IT corridor and a Knowledge Corridor
consisting of engineering colleges constructed on water bodies, and automobile
and telecom SEZs .Gated residential areas built on important drainage courses
regulatory controls .The water bodies should be protected from encroachments. Vulnerability
to hydro-meteorological disasters especially in urban context stems from large
concentration of people, infrastructure and financial assets .Disaster risks
and impacts due to environmental impacts of migration, slum habitations, poor
waste management over the dramatic changes in land-uses .Land-uses issues
especially ,natural flood controls in form of wetlands, raised housing, better
plinth in building and sanitary, maintaining open areas are examples of
Risk sensitive land-use planning has two fold
environments and landscapes to avoid or reduce flooding,
(b) managing developments and human
settlements from exposure/impact of floods .
Land-use influences in terms of drainage and debris,
flow gradient, rainwater amount and intensity over sewerage, urban forestry,
pose serious challenges in flood disaster risk assessment, environmental
planning in cities and disaster mitigation.