Adapting to Climate Change in Asia’s Coastal Megacities Kishore U. Gajbhiye

1. Adapting to Climate Change in Asia’s Coastal Megacities Kishore U. Gajbhiye Additional Commissioner Municipal Corporation of Greater Mumbai, India

2. Mumbai Mumbai lies at the mouth of the Ulhas River off the western coast of India, in the coastal region known as the Konkan. It sits on Salsette Island, partially shared with the district of Thane. Much of the city lies just above sea level, with average elevations ranging from 10 m (33 ft) to 15 m (49 ft). Northern Mumbai is hilly, and the highest point in the city is 450 m (1,476 ft). The city spans a total area of 603 km² (233  sq mi).

3. Topography Merger of 7 islands in city area, 4 islands and hilly areas in suburbs Surrounded by the Arabian Sea and Thane creek Much of the area is close to sea level Gravity drainage system designed in 1920s, affected by high/low tides During high tide, flood gates are closed to stop ingress of sea water. Result: No drainage of storm water, water logging/flood occurs during heavy rains coupled with high tide

4. Topography • Network of drains below roads in city area and open drains in suburbs • Storm Water Drainage (SWD) Network • more than 150 years old in city area • designed for rainfall of 25 mm per hour and Run-off co-efficient of 0.5 • Brihan Mumbai Storm Water Drain Project (BRIMSTOWAD Project) Report (1993) - the city is fully developed and the change in land use pattern has led to increase in Run off coefficient to almost 1.0

5. Mumbai Covers an area of about 437.71 Sq. Km. Houses about 11.9 Million people (c. 2001) Population density of about 27,209 people per Sq. Km (c. 2001) Approximately 60% population resides in informal settlements Approximately 27,68,910 structures including residential, commercial and industrial

6. Mumbai: Position • Between 18 and 19.2 Northern Latitude • Between 72 and 73.0 Eastern Longitude • East to West extends – 12 Km broadest • North-South extending about 40Km • Height – 10 to 15m above sea level

9. Floods in Mumbai The thrusts of disaster management in Mumbai since the year 2005 is floods during the monsoon. Mumbai and Singapore both get about 2500 mm. of rainfall. However, Singapore rainfall is better distributed over the year, while Mumbai rainfall is during two months of July and August. Rapid urbanization has substantially increased the population.

10. Increasing population Habitation comes first, water supply next, roads thereafter and storm water drainage at the last. Construction of houses is largely at private initiatives while storm water drainage is to be done by the Municipal Corporation. Analysis by Shri Sanglikar, retired DMC shows that the ratio of number of flooding days with rainfall of more than 75 mm increased from 1:7 in the 40’s to 1:1 in the 70’s to 1.5:1 in the last decade.

11. Many areas of Mumbai below sea-level Mumbai is originally a group of 7 islands. Many areas of the city are reclaimed from the sea and are at a level of 5 meters and above from the low tide level. The high tides during July and August are about 4.80 meters and occur between 12.00 mid-noon to 02.00 p.m. in the few days after the full moon day (Amavasya). This situation occurs only for 4 days in a month for about 5 hours each. Heavy rainfall just before these days can create panic situations since water cannot discharge into the sea.

12. Low-lying area in Mumbai Railway lines are typically about 10 meters above low tide level and the Subways are very close to high tide level. Western Railway 43 culverts, Central Railway 35 culverts and Harbour lines 27 culverts. In addition there are 82 chronic flooding spots.

13. Disaster Preparedness MCGM had put 196 temp. pumps to discharge water 6 Search and Rescue teams zone-wise are kept ready under the fire brigade 600 personnel from Civil Defence and 10 persons per Ward from an NGO – Aniruddha Academy were kept ready 288 retaining walls in 74 places have been undertaken by the Slum Improvement Board BEST keeps 500 buses ready

14. Mithi River Mithi river is the boundary between South Mumbai and western suburbs and also divides the western and eastern suburbs. Flooding caused havoc in 2005. In Phase-I, 5.68 lakhs cu.m. silt has been removed. 3.70 cu.m. lakhs cu.m. silt has been removed in Phase-II after March 2007. 2652 residential and 1148 commercial structures removed. 1769 residential and 349 commercial structures rehabilitated Additional bridges at Kranti Nagar and Kurla-Kalina Road started.

15. Storm Water Drainage Typically a city can cope up with 10 per cent of annual rainfall in a day. On 26th July 2005, almost 35% of annual rainfall occurred on a single day. Hon’ble Prime Minister sanctioned a special grant of Rs. 1200 crores outside JNNURM as 100% subsidy. The work involves widening of drains and construction of pumping stations. Rehabilitation of slums up to 01.01.2000. An amount of Rs. 280 crores has been spent by December 2008 and we will be able to ask for the next installment.

16. Future Plans Sea level is increasing by 3 mm. per year. Additional measures such as gates on Vihar and Tulsi may be necessary. Holding ponds upstream of airport in Mithi would be necessary since widening in the tidal portion does not help at high tide times. Delay by Airport Authority in widening Mithi River under the runway, a cause of concern.

17. The Disaster Management Act, 2005 and Its Implications on Greater Mumbai

18. NDMA Sec-3 State DMA Sec: 14 District DMA Sec: 25 Local Authority Sec: 41 Hierarchy of Authorityas per the DM Act-2005

19. Coordination Institutional Mechanisms • State Disaster Management Sub-Committee for Mumbai • Headed by ACS (Home) • Ward wise Disaster Management Committee Headed by Assistant Commissioner of Ward

20. MantralayaGoM Central Railway FireBrigade Western Railways Police MCGM Traffic Control MMRDA Metrology Dept BEST Coordination • Effective coordination among all agencies necessary for effective response • Regular preparedness meetings of institutional mechanism

21. Effects of Disaster

27. Where We Went Wrong ? • Communication System fully collapsed. • No single point relief and rescue center at many places. • Disaster Management System not designed for worst. • Low level of awareness among people. • Unorganized mobilization of resources.

28. Mumbai vis-à-vis the World

29. Mumbai’s Population Dynamics • Average population density • 27,209 persons per Sq. Km (population / area) • Majority of the population lives in the suburbs and commutes to the city area in south for work in the morning and back home in the evening • Case Study - Ward ‘A’ (South Mumbai) • Daytime population : 45,00,000 persons • Density : 3,94,390 persons / Sq. Km. • Nighttime population : 2,00,000 persons • Density : 17,528 persons / Sq. Km.

30. Indian Monsoon is Unique! • Mumbai AAR 2401mm • July average rainfall 868 mm > London’s annual 611 mm • Singapore also receives 2150 mm, but spread throughout the year (max monthly is 304 mm in Dec; BOM in a day!)

31. Indian Monsoon is Unique! Over 70 -95% rainfall in 4 months So well-planned approach required for managing urban flooding disasters in Indian cities

32. Average Rainfall in Mumbai

33. Average Rainfall in Mumbai

34. Sea Level/ Tidal Information

35. Dates to watch in 2009 • Notable tide levels (at Apollo Bunder) are • June 2009:- 4.95, 4.97 and 4.90 m from 24-26 June 2009 • July 2009:- 5.01 m., 5.05 m. and 4.94 m. from 23-25 July 2009 • August 2009:- 4.81, 4.94 and 4.92 m. rfom 20-22 August 2009 

36. Annual Increase in Sea Level • Recent studies (Unnikrishnan, et al., 2006) indicate a rate of rise of 0.78 mm/year for Mumbai based on analysis of data from 1878-1994.  

37. Effect of Urban Heat Island on Hydrologic Processes Rising Heat and Cloud Formation as a Result of the Urban Heat Island Effect http://www.gsfc.nasa.gov/topstory/20020613urbanrain.html

38. Urban Heat Islands Increase Rainfall Rates around cities by 48-116 % (NASA) Winds Interact with Urban-induced Convection to Produce Downwind Rainfall http://www.gsfc.nasa.gov/topstory/20020613urbanrain.html

39. Preventive Measures Undertaken • In order to avoid flooding & water logging, the Municipal Corporation of Greater Mumbai carries out number of activities such as: • Systematic desilting of Storm Water Entrances, laterals & manholes. • Desilting of open/ dhapa/ pipe/ arch/ box drains. • Desilting of minor and major nallas, outfalls. • Replacement of dilapidated Storm Water Drains. • Providing additional Storm Water Entrances. • Conversion of dhapa drains in to pipe drains. • Augmentation & repairs of drains & Nallas. • Removal of obstructions from the drains/ Nallas.

40. Long Terms Measures • In 1990, BRIMSTOWAD Consultants carried out scientific study of following aspects: • The existing condition of Storm Water Drain system and the topography surrounding it. • Repairs/reconstruction of Storm Water Drain System. • Preparation of update plans. • Analysis of present system and increasing its capacity considering rainfall of 50 mm per hour.

41. Categories Unit Rs. in Crores City Area Western Suburbs Eastern Suburbs TOTAL Rehabilitation of Old SWD System 24.45 Kms 203.62 203.62 Widening & Training of Nalla 102.95 Kms 153.33 272.31 283.27 708.91 Pumping Stations 8 Nos 148.00 111.00 29.00 288.00 Total 504.95 383.31 312.27 1,200.53 Proposed Categories of Works & Fund Requirement

42. BRIMSTOWAD Report M/s.Watson Hawksley India Pvt. Ltd. were appointed as consultant in 1989 to study the whole SWD system. Their report, submitted in 1993, is called “BRIMSTOWAD” Report i.e. Brihanmumbai Storm Water Drainage

43. Status of BRIMSTOWAD Project • Projects in two phases • Phase I - • Consists of 20 works • Cost of works 356 crores • Works completed - 10 nos • Work in progress - 10 nos • Expenditure upto December 2008 – 280 cr. • Expected date of completion – March 2009 • Phase II • Nos of works under taken – 38 • Out of 38 works 27 works are in progress. Tenders are being prepared for remaining 11 works. • Total cost of works - 843.45 cr. • Expected date of completion – March 2011

44. BRIMSTOWAD Project • Projects being carried out under BRIMSTOWAD Project with the aid of Government of India. • GIS based urban Storm Water Drain management system. • Hydro mechanism of Storm Water Drain System. • Flood warning system • Rehabilitation / upgradation of nallas/ storm water system

45. Major Recommendations • Change of design criteria from 25 mm/hr to 50 mm/hr. rainfall intensity and coefficient of runoff as 1.00 from the earlier value of 0.50. • Rehabilitation of old/dilapidated SWD system in the City. • Augmentation of the SWD system for the new design criteria with tidal effects. • Training, widening and deepening of nallas. • Augmentation of railway culverts at various flood prone areas. • Removal of obstructions of water mains, cables, etc. in the SWD system. • Removal of encroachments, structures coming in the water courses. • Provision of pumping stations at the city outfalls at Haji Ali, Love Grove (Worli) and Cleaveland Bunder .

46. Implementation of BRIMSTOWAD Report • Total cost of improvements suggested in the Report was Rs. 616.30 Cr. • (Figures based on 1992 prices and planned span of 12 years) Works could not be taken up systematically mainly because of • Financial constraints • Encroachment on sites • In the past 10 years, works worth about Rs. 260 Cr. only could be completed. • At today’s prices:- • Cost of the remaining Project works - Rs. 1200 Cr. • Cost of rehabilitation of Project Affected Persons - Rs. 600 Cr. • After the experience of the 26th July 2005, the MCGM has taken up implementation of the BRIMSTOWAD Report on top priority. Works are proposed to be completed in four years . • The Central Government has been requested for financial assistance. Technical Appraisal of the Project has been completed by the CPHEEO and the Project is also cleared by the EFC. The Project is awaiting final approval of the Cabinet Committee on Economic Affairs.

47. Flood Warning Systems: Initial Steps • Automatic rain gauges to study exact pattern of the rain all over Mumbai city & suburb • Fire brigade being first respondent and on 24 hours alert, the rain gauges will be installed at 26 fire brigade stations – across Mumbai • This rain gauges data transmitted to control room every 15 minutes • The rain gauges can be further calibrated to give alarm at prefixed rainfall intensity • This data will serves as warning and evacuation signal if required • The approximate cost of equipment / system is Rs. 2 Crores • Expertise from IIT Bombay for Early Warning System being utilized

48. The MCGM’s EOC • An Emergency Operations Center is equipped with: • An array of communications systems • Television sets tuned to major news channels • Networked Computer Systems with DM Software • Video Conferencing Setup • Conference and Press Rooms • Water Supply and Ration Stocks • Uninterruptible Power Supplies with Generators • Pantry, Dormitory and Toilet facilities • Thus, it is a self-sufficient control center built to withstand and outlast disasters

49. Communication in Disaster Management • Land lines, Hot lines, Mobile phones - both GSM and CDMA • Ham radio , VHF wireless sets , Video conferencing • TETRA (Terrestrial Trunk Radio Access) • TETRA will give all voice , data and video • Transfer from one location to other location • Satellite phones –These phones are fail proof and work under all conditions.

50. Works being carried out under Brimstowad Project • Construction of pumping stations at LGP, Hajiali, Cleavland Bunder, Irla nallah. • Proposed pumping stations at Britania Outfall, Mahul Creek, Mogra nallah and Khar Danda • 45 Outfalls which are below mean sea level will be closed by gate type mechanism. • Brimstowad report 1992 is reconciled by 0.5 x 0.5 mtr. GIS mapping.