URBAN FLOODS –A RELATIONSHIP BETWEEN DISASTER AND DEVELOPMENT:CHENNAI FLOODS 2015 1 summary 2 introductionChennai, State capital of Tamil Nadu lies in theEastern Coast of South India where three watercourses through it namely, CooumRiver, Adyar River and Buckingham Canal. Chennai is the fourth largestMetropolitan in India. 2.1 GROWTHOF CHENNAI CITYChennai, having a plain terrain is bounded by Bay ofBengal in the East with an average elevation 6.7m from the mean sea level.Chennai experiences most of its rainfall during October to December. Averageannual rainfall is about 1200 mm – 1300 mm being situated on the coastal side.
Figure 11.2 Growth of Chennai CitySource: Chennai MunicipalArea Cooperation 2.2 HISTORYOF 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.
Rainfallwas 235 mm in 2015 only during October – December period. 2.3 CAUSESOF CHENNAI FLOODS: 3 ARELATIONSHIP BETWEEN DISASTER AND DEVELOPMENT:Thegraphic shows the various “orientations” with which you may analyze the “field”of development and disaster vulnerability. The field is divided into positiveand negative aspects of the disaster/ development relationship by the verticalaxis. The right half reflects the positive or optimistic side of therelationship and the left side of the diagram deals with the negative aspectsof the relationship.
The short statement given in each quadrant sums up thebasic concept derived from the overlap of the two realms. 1.Disasters setback development programming destroying years of developmentinitiatives.e.g.transport and utility systems are destroyed by a flood.
2.Rebuilding after a disaster provides significant opportunities to initiatedevelopment programsAself-help housing program to rebuild housing destroyed by an earthquake teachesnew skills, strengthens community pride and leadership and retains developmentdollars that otherwise would be exported to large construction companies.3.Development programs can increase an area’s susceptibility to disasters.Amajor increase in livestock development leads to overgrazing, which contributesto desertification and increases vulnerability to famine.4.
Development programs can be designed to decrease the susceptibility todisasters and their negative consequences.Housingprojects constructed under building codes designed to withstand high windsresult in less destruction during the next tropical storm.4 A CASEOF CHENNAI: Urbanization: Chennai – the capital city of Tamil Nadu is also linked withnumerous economic prospects & the facilities also. Chennai has a large migrantpopulation which accounts to 28% of Chennai’s population in 2011. Due to this,the encroachment of all water bodies as slums & for the development ofurban infrastructure reduces the rain water carriage capacity of the fewexisting water ways. Development of transportation facilities like MRTS allalong the water ways in some areas and subsequent developments of that alsoaggravates the flood risks of Chennai in addition to health risks URBAN LANDUSE CHANGES, GOVERNANCE AND FLOODS:Causesof increased flooding in Chennai are identified as:Uncontrolledurban sprawl and loss of natural drainage. Inadequacy of storm water drainagesystem and lack of maintenance.
Increase in impervious surfaces. Paving ofroadsides, park and open areas causing flood severity. Many of the waterbodies including man-made wetlands/lakes and natural depressions and havedisappeared due to waste and development or slum encroachments .
Lack ofcoordination between agencies. Figure11.5 Land CoverSource: IRSTheworst rainfall to have hit the Capital of Tamilnadu in past 11 years . Buildingnew Flats, Houses by cutting trees , destroying riverbed’s , natural ponds,poor water drainage systems have at last showed how dangerous it was for theplace. Till now in the 24 hours gap Chennai received 246.
5 mm rainfall, whichwas very huge. It was in November 1976 when Chennai was thundered by rainfallsand a record of 452.4 mm was received. In 2015 with rain of 246.
5 mm itself ithas caused lot of damage. So it is unimaginable to know what will happen ifhistory of 1976 repeats. 4.1 DISASTER-DEVELOPMENT-INFRASTRUCTURE: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, Adyaroverflowed its banks and invaded first-floor houses., Chennai has a host ofexpensive infrastructure ,a brand-new airport built on the floodplains of theRiver Adyar.
A sprawling bus terminal in flood-prone Koyambedu Mass RapidTransit System constructed almost wholly over the Buckingham Canal and thePallikaranai marshlands .Expressways and bypass roads constructed with no mindto the tendency of water to flow. An IT corridor and a Knowledge Corridorconsisting of engineering colleges constructed on water bodies, and automobileand telecom SEZs .Gated residential areas built on important drainage coursesand catchments 5 CONCLUSION: Planning andregulatory controls .The water bodies should be protected from encroachments.
Vulnerabilityto hydro-meteorological disasters especially in urban context stems from largeconcentration of people, infrastructure and financial assets .Disaster risksand impacts due to environmental impacts of migration, slum habitations, poorwaste management over the dramatic changes in land-uses .Land-uses issuesespecially ,natural flood controls in form of wetlands, raised housing, betterplinth in building and sanitary, maintaining open areas are examples ofconcern. Risk sensitive land-use planning has two foldimplications (a) managingenvironments and landscapes to avoid or reduce flooding, (b) managing developments and humansettlements 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, environmentalplanning in cities and disaster mitigation.