This document summarizes a study report on the 2005 Mumbai floods in India. It describes how over 944 mm of rainfall fell within 24 hours, overwhelming the city's drainage system and causing widespread flooding. Over 500 people died and millions were displaced. Key factors that exacerbated the flooding included inadequate storm drains, silted natural drains, and uncontrolled urban growth. The floods revealed deficiencies in disaster preparedness and management. They highlighted the need for coordinated response among authorities and empowered local communities.

1. UPC3.3- Urban Risk and Disaster Management
September 30, 2020
Mumbai Floods (2005)
A study report on the urban floods in the city of Mumbai, Maharashtra on July 26 2005,
from the purview of disaster management studies- towards the partial fulfilment of credits
for the course UPC 3.3- Urban Risk and Disaster Management.
Submitted by:
Prasad Dipak Thanthratey
SPA/NS/UP/1409
Guided by:
Dr. Chandrani B. Neogi
School of Planning and Architecture, New Delhi

2. URBAN RISK AND DISASTER MANAGEMENT- MUMBAI FLOODS OF 2005
PRASAD DIPAK THANTHRATEY SCHOOL OF PLANNING AND ARCHITECTURE, NEW DELHI
The Incident
On July 25, 2005, The Indian Meteorological Department station located at Santa Cruz,
Mumbai recorded 944.22mm of rainfall, which was around 35% of annual rainfall within a 24-
hour period. Out of those, 75% of the downpour, i.e., 709mm was received in a first five-hour
period (between 2:30 pm-7:30 pm). Soon water-logging at the tracks brought the local trains
at a halt. This in turn, led to a multi-fold increase in traffic on roads.
An unusual feature of this rainfall was that the southern island city received just 73.4mm of
rainfall. The northern suburbs of Kurla, Kalina, Andheri, Saki Naka, Chembur, Govandi, Malad,
and low-lying areas like Dharavi and Bandra-Kurla Complex, which were reportedly flooded
the most.
The city was deluged, expeditiously.
The Impact
It was assumed that at least a third of the total surface area of the city was flooded. Most
communication lines were severely disrupted if not lost- for durations ranging from a few
hours to weeks in a few cases. The slectricity supply was shut off for most parts. The city’s cell
phone network also weakened, leaving families with no way of verifying the whereabouts
of their loved ones. Public transit came to a standstill, stranding hundreds of thousands of
people at different points in the city. The suburban rail system was inoperable for at least 18
hours. All India Radio reported that 1,50,000 people were stranded across different suburban
railway stations, some for almost 24 hours.
And undoubtedly so, the loss to life and property was substantial. According to official
figures, 546 people died in Mumbai that day and its immediate aftermath -- including 179
who drowned and 75 killed in landslides. There was also an unknown number of the poorest
slum dwellers who lived in unauthorised dwellings and remained simply untraceable.
Countless others were also injured. More than 3,00,000 people required immediate medical
attention. The fact that the floodwaters did not regress for days in some areas compounded
the situation and led to outbreaks of diseases like leptospirosis, malaria, diarrhoea, dengue
etc.
The floods damaged around 20,000 cars, 2,500 BEST buses, and innumerable two and three-
wheelers. Around 2,00,000 tonnes of garbage- washed away, foodstuffs, appliances- had
to be cleared up. Moreover, to prevent an epidemic of monsoon-related diseases, 24
metric tonnes of bleaching powder, and 2 metric tonnes of disinfectants were used.
Mumbai airports were also closed for more than 30 hours, with water flowing over the runway
and even through the terminal buildings. More than 700 flights were indefinitely delayed
and/or cancelled, leaving international travellers stranded at the airport too.
The total extent of losses was measured at around ₹2800 crores, out of which infrastructural
losses alone constituted at around ₹1000 crores.

3. URBAN RISK AND DISASTER MANAGEMENT- MUMBAI FLOODS OF 2005
PRASAD DIPAK THANTHRATEY SCHOOL OF PLANNING AND ARCHITECTURE, NEW DELHI
The Points of Catastrophe:
When the vulnerabilities joined forces with the Heavy Rainfall
 Storm Water Drain Shortcomings:
Mumbai’s drainage system was planned in the early 20th century for a maximum
rainfall of 25 mm per hour, with a 0.5 runoff coefficient- that is, supposing that half the
rain would be absorbed and only half would flow into the drainage system.
On stormy monsoon days in Mumbai, the intensity can reach 50 mm to 100 mm an
hour. But on the dreadful day of July 26, it peaked at 136 mm.
With the onset of extensive and unmethodical urbanization, most surface areas are
now either hardscaped. Thus, the runoff coefficient is now virtually 1, with very little
rainwater being absorbed in all.
Also, many of the city’s drains are in poor physical condition, because of age, poor
workmanship, as well as an intrusion by other services such as water and sewer pipes.
Access for maintenance is also restricted, frequently by unauthorized development.
 Natural Drains and Watershed Shortcomings:
The Mithi river, which has been contemplated as a filthy drain- is supported by a
network of nullahs, that provide natural drainage to the city. But over the years, it
witnessed routine dumping of waste by slums and untreated effluents by industries
into them.
All these deposits had already silted the nullahs and so, have already reduced
capacity to drain stormwater. Besides, land reclaimed from their banks has long
been encroached for development projects.
To exacerbate the problem, -the airport was expanded by over 181 hectares. To
facilitate the extension of the taxiway of the Sahar international airport, the Mithi river
has been bent 90 degrees at the airport by building a bridge over the river. On the
day of July 25, the drain bottlenecked, overflowed, and emptied toxic sludge and
sewage into the Mahim Bay –triggering havoc in the suburbs.
 Frenzied Pace of Growth in the Northern Suburbs:
Urban Growth in many suburbs of Mumbai is disordered and constructions are being
carried out without due attention to the natural drainage. The drainage plans in
northern suburbs is arranged and made for whenever required in a particular area
and are not planned not comprehensively.
For example, in the early 1990s, it was brought under the notice of the Environment
Ministry of the Government of India that sanctioning the Bandra-Kurla complex will
lead to disaster. But they still gave a green signal to this ambitious project.
Furthermore, no environmental clearance is mandatory for large urban construction
projects in northern Mumbai.

4. URBAN RISK AND DISASTER MANAGEMENT- MUMBAI FLOODS OF 2005
PRASAD DIPAK THANTHRATEY SCHOOL OF PLANNING AND ARCHITECTURE, NEW DELHI
Implications on Practices and Policies
 The havoc these floods instigated in Mumbai accelerated to the passing of the
National Disaster Management bill of 2005 into an act. The Act called for the
formation of the National Disaster Management Authority (NDMA), with the PM as
chairperson. It directed all State Governments to establish a State Disaster
Management Authority (SDMA), to ensure "timely and effective response to disaster".
 The ineptitude to act during the times of crisis revealed that the administration was
woefully unprepared to face disasters. Consequently, it was agreed that informed,
trained bureaucrats can offer a more co-ordinated response. The need for regular
interaction with experts in training and research institutions was also observed. And
so, the National Disaster Management Act of 2005 granted statutory organisation
status to National Institute of Disaster Management (NIDM).
 After the floods, a fact-finding committee of experts was set up to assess the disaster
preparedness and management of Mumbai. A comprehensive report was published
the following year, which developed into a handbook for the municipal corporation,
considerably influencing the 2009 national guidelines on urban flood management.
 There was a shift of approach by which the agencies operate: from conventional/
reactive to a strategic one. The administration, police, and the citizens at large
seemed more organised in the 2017 Mumbai floods.
However, the old problem of multiple planning authorities — Mumbai Metropolitan
Region Development Authority, Municipal Corporation of Greater Mumbai (MCGM),
Slum Redevelopment Authority, Mumbai Metro Rail Corporation Ltd – prevails.
 It was observed that empowered communities, with strong civic sense and resilience
-respond better, and that most of the disaster response has to be ‘people-centric’.
So, in subsequent floods, owing to the augmented collaborations, better
coordination was exhibited amongst the state, local authority, institutions, religious/
social bodies, and private actors.
Bibliography
1. State Disaster Management Authority, April 2016. Maharashtra State Disaster
Management Plan, Disaster Management Unit Relief and Rehabilitation Department
Government of Maharashtra.
2. Concerned Citizens’ Commission, July 26, 2006. Mumbai Marooned: An Enquiry into the
Mumbai Floods 2005
3. Joshi P.,2017. Mumbai swamp, comparing July 2005 to August 2017, The Indian Express,
September 1. Available at:
https://indianexpress.com/article/opinion/mumbai-floods-swamp-excessive-rains-
drainage-system-july-2005-august-2017-4823348/
(Accessed on: 27 September 2020)
4. D'Monte D. 2017, Mumbai after the 2005 Deluge, India Together, August 5. Available at:
http://indiatogether.org/mumbai-after-the-2005-deluge-op-ed
(Accessed on: 27 September 2020)
5. Pathak J., Management of Urban Floods in Mumbai, India. Available at:
https://www.preventionweb.net/files/section/230_mumbaifloodShanghai.pdf
(Accessed on: 27 September 2020)