Abstract
Projections by the Intergovernmental Panel on Climate Change suggest that there will be an increase in the frequency and intensity of climate extremes in the 21st century. Kolkata, a megacity in India, has been singled out as one of the urban centers vulnerable to climate risks. Modest flooding during monsoons at high tide in the Hooghly River is a recurring hazard in Kolkata. More intense rainfall, riverine flooding, sea level rise, and coastal storm surges in a changing climate can lead to widespread and severe flooding and bring the city to a standstill for several days. Using rainfall data, high and low emissions scenarios, and sea level rise of 27 cm by 2050, this paper assesses the vulnerability of Kolkata to increasingly intense precipitation events for return periods of 30, 50, and 100 years. It makes location-specific inundation depth and duration projections using hydrological, hydraulic, and urban storm models with geographic overlays. High resolution spatial analysis provides a roadmap for designing adaptation schemes to minimize the impacts of climate change. The modeling results show that de-silting of the main sewers would reduce vulnerable population estimates by at least 5 %.
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Notes
Countries identified by the World Bank as Low Income or Lower Middle Income.
http://www.dartmouth.edu/~floods/dbtop.html, accessed December 2011.
http://www.dartmouth.edu/%7Efloods/Archives/2008sum.htm, accessed December 2011.
http://www.reliefweb.int/rw/RWB.NSF/db900SID/EDIS-79BQ9Z?OpenDocument, accessed December 2011.
The most recent evidence suggests that sea level rise could reach 1 m or more during this century (Hansen and Sato 2011; Vermeer and Rahmstorf 2009; Pfeffer et al. 2008: Hansen 2007; Rahmstorf 2007; Overpeck et al. 2006; Hansen 2006). This more recent research has focused on the dynamic implications of ice sheet instability, and their results include estimates significantly beyond the upper limit of the range cited by the IPCC’s Fourth Assessment Report (2007): a 90 % confidence interval of 18–59 cm based principally on thermal expansion, with an additional 10–20 cm allowed for a potential dynamic response from the Arctic and Antarctic ice sheets. If such sea level rise occurs, it will have a significant impact on tidal surges and drainage in the KMA.
An increase in sea surface temperature is strongly evident for all latitudes and oceans. The current scientific consensus, summarized by IPCC (2011), holds that a warmer ocean is likely to intensify cyclone activity and heighten storm surges. For the Bay of Bengal, Karim and Mimura (2008) estimate that with a 1 m SLR and an increase of 2° in ocean surface temperature, storm surges in neighboring Bangladesh would increase by 13 %. The KMA would experience intense flooding with intensification of cyclonic storm surges.
This is an estimate of the time interval between two precipitation events of a particular intensity. It is a statistical measure of the average recurrence interval over a long period of time and the inverse of the probability that the event will be exceeded in any one year. Hence, a 30, 50, or 100-year precipitation level has a 3.3, 2, and 1 % chance, respectively, of occurring in any given year.
For details, see Sugiyama (2008).
In the absence of scientific sea level rise estimates corresponding to various emission scenarios for the Bay of Bengal near the coast of India, upon consultation with the government of West Bengal, an estimate of 27 cm sea level rise by 2050 was adopted from the World Bank-led Economics of Adaptation for Climate Change study for neighboring Bangladesh (World Bank 2011). This 27 cm sea level rise is a point estimate of “medium sea level rise” by 2050 derived from Rahmstorf (2007). See Neumann (2009) for details.
HEC-RAS is a one-dimensional steady and unsteady flow hydraulic model developed by the U.S. Army Corps of Engineers (U.S Army Corp of Engineers 2002).
SWMM is a dynamic rainfall-runoff simulation model used for single event or long-term (continuous) simulation of water runoff from primarily urban areas.
The KMC area covered by town and suburban sewer systems has a total installed pumping capacity of 82 cubic m/s with a current working capacity of 59 cubic m/s.
It has been found that a depth level below 0.25 m produces little damage in most affected areas as people have learned to adapt to this level of flooding as a common occurrence every year. Buildings in the KMA are generally raised to avoid flooding up to a water depth level of 0.25 m.
A ranking of vulnerable wards was also done with respect to percentage of area flooded without assigning any vulnerability index by flooding depth. The results from both procedures resulted in similar findings for the ten most vulnerable wards.
There has been no regular maintenance. The dry weather flow canal was last maintained in 1999 and the storm weather flow canal was last maintained in 2003–04.
References
Asian Development Bank (2008) Climate Change ADB Programs. Strengthening mitigation and adaptation in Asia and the Pacific http://www.donorplatform.org/component/option,com_docman/task,doc_view/gid,940. Accessed December 2011
Chatterjee RS, Fruneaub B, Rudant JP, Roy PS, Frison P-L, Lakhera RC, Dadhwal VK, Saha R (2006) Subsidence of Kolkata (Calcutta) city, India during the 1990s as observed from space by Differential Synthetic Aperture Radar Interferometry (D-InSAR) technique. Remote Sensing Environ 102:176–185
Dickson E, Tiwari A, Baker J, Hoornweg D (2010) Understanding urban risk: an approach for processing disaster and climate risks in cities. World Bank, Washington, Mimeo
Dube SK, Rao AD, Sinha PC, Murty TS, Bahulayan N (1997) Storm surge in the Bay of Bengal and Arabian Sea: the problem and its prediction. Mausam 48:283–304
EM-DAT (2010) The International Disaster Database. Prepared by the Centre for Research on the Epidemiology of Disasters-CRED http://www.emdat.be/database. Accessed June 2012
Emery D, Finnerty J, Stowe J (2007) Corporate financial management, chapter 6. In: Risk and return. Prentice Hall, Upper Saddle River, NJ
Hansen J (2006) Can we still avoid dangerous human-made climate change? Presentation on December 6, 2005 to the American Geophysical Union in San Francisco, California. Available at: http://www.columbia.edu/~jeh1/newschool_text_and_slides.pdf. (Accessed February, 2011)
Hansen J (2007) Scientific reticence and sea level rise. Environ Res Lett 2
Hansen JE, Sato M (2011) Paleoclimate implications for human-made climate change. NASA Goddard Institute for Space Studies and Columbia University Earth Institute. Mimeo
Hanson S, Nicholls R, Ranger N, Hallegatte S, Corfee-Morlot J, Herweijer C, Chateau J (2011) A global ranking of port cities with high exposure to climate extremes. Clim Chang 104:89–111
IPCC Fourth Assessment Report: Climate Change (2007) AR4 http://www.ipcc.ch/publications_and_data/publications_and_data_reports.htm#1, Accessed December 2011
Jain I, Rao AD, Jitendra V, Dube SK (2010) Computation of expected total water levels along the east coast of India. J Coast Res 26(4):681–687
JICA (2008) “Interim report, study on climate impact adaptation and mitigation in Asian coastal mega cities.” Prepared by the Integrated Research System for Sustainability Science, University of Tokyo
Karim MK, Mimura N (2008) Impacts of climate change and sea-level rise on cyclonic storm surge floods in Bangladesh. Glob Environ Chang 18(3):490–500
KMC (2010) Basic statistics of Kolkata. https://www.kmcgov.in/KMCPortal/jsp/KolkataStatistics.jsp Accessed December 2011
KMDA (2010) http://www.kmdaonline.org/html/about-us.html Kolkata Metropolitan Development Authority. Accessed December 2010
KMPC (2004) Vision 2025—a perspective plan of Kolkata Metropolitan Authority, Kolkata Metropolitan Planning Committee
Kolkata Municipal Corporation (2007) Kolkata environmental improvement project: sewerage and drainage master plan for Kolkata. Mimeo
Nakicenovic N, Swart R (eds) (2000) Emissions scenarios. Special report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, p 559
Nandy DR (2007) Need for seismic microzonation of Kolkata megacity, Proceedings of workshop on microzonation, Indian Institute of science, Bangalore, India, June 26–27
Neumann J (2009) Sea-level rise scenarios for the World Bank economics of adaptation to climate change study. April. Mimeo
NIST/SEMATECH e-Handbook of Statistical Methods (2010) http://www.itl.nist.gov/div898/handbook/eda/section3/eda366g.htm, Accessed December 2011
Overpeck J, Otto-Bliesner B, Miller G, Muhs D, Alley R, Kiehl J (2006) Paleoclimatic evidence for future ice-sheet instability and rapid sea-level rise. Science 311:1747–1750
Pfeffer WT, Harper JT, O’Neel S (2008) Kinematic constraints on glacier contributions to 21st-century sea-level rise. Science 321:1340–1343
Rahmstorf S (2007) A semi-empirical approach to projecting future sea-level rise. Science 315:368–370, http://www.pik-potsdam.de/~stefan/Publications/Nature/rahmstorf_science_2007.pdf
Sugiyama M (2008) The study on climate impact adaptation and mitigation in Asian coastal mega cities of integrated research system for sustainability science, University of Tokyo. Final Report to JICA
UN Department of Economic and Social Affairs (2005) World urbanization prospects: the 2005 revision
UNFCC (2008) Physical and socio-economic trends in climate-related risks and extreme events, and their implications for sustainable development http://unfccc.int/resource/docs/2008/tp/03.pdf, Accessed December 2011
U.S Army Corp of Engineers (2002) HEC-RAS river analysis system: hydraulic reference manual, November 2002
Vermeer M, Rahmstorf S (2009) Global sea level linked to global temperature. Proc Natl Acad Sci 106(51):21527–21532
World Bank (2010a) Cities and climate change: an urgent agenda
World Bank (2010b) Climate risks and adaptation in Asian coastal megacities: a synthesis report
World Bank (2011) Economics of adaptation to climate change: Bangladesh http://climatechange.worldbank.org/sites/default/files/documents/EACC_Bangladesh.pdf. Accessed December 2011
World Meteorological Institute (2010) Current extreme weather events. http://www.wmo.int/pages/mediacentre/news/extremeweathersequence_en.html, Accessed December 2011
Acknowledgment
We would like to extend our special thanks to Mr. Debal Ray (Department of Environment, Government of West Bengal), Mr. Ardhendu Sen (Chief Secretary, Government of West Bengal), Mr. Sushit K Biswas (Kolkata Environmental Improvement Project), Mr. Nilangshu Basu (Kolkata Municipal Corporation), and Mr. Samar Ghosh (Secretary Health and Family Welfare Department, Government of West Bengal) for providing substantial guidance. We are thankful to Anna C. O’Donnell, Dan Biller, Adriana Damianova, Megumi Muto, John Pethick, Bradfort R. Philips, Neeraj Prasad, Jack Ruitenbeek, Walter Vergara, and participants of the stakeholder workshop in Kolkata for useful comments and suggestions. We are grateful to Ms. Arati Belle and Ms. Sonia Sandhu for help with an earlier draft.
Financial support for this study was provided by Trust Fund for Environmentally Socially Sustainable Development supported by Finland and Norway.
The views expressed here are the authors’ and do not necessarily reflect those of the World Bank, its Executive Directors, the countries they represent, or of the Government of India.
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Dasgupta, S., Gosain, A.K., Rao, S. et al. A megacity in a changing climate: the case of Kolkata. Climatic Change 116, 747–766 (2013). https://doi.org/10.1007/s10584-012-0516-3
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DOI: https://doi.org/10.1007/s10584-012-0516-3