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Flooding is an accumulation of water in an area either by direct rainfall irresistible to the volume of drainage systems or a spill of huge amount of water from water bodies beyond normal limits. It could be localized, impacting a small area or could be vast or massive, impacting very large area. Urban flooding is caused by heavy rainfall overwhelming drainage capacity. It already has large economic and social impacts. These are very likely to increase if no changes are made to the unplanned development of buildings and infrastructure and poor management of urban drainage. Urban floods are a great disturbance of daily life in the city. Urbanization in developing countries doubled from less than 25% in 1970 to more than 50% in 2006. By 2020, seven of the world's ten largest economies will be from Asia. At the same time, Asia in one of the fastest urbanization regions in the world. In 2000, 37% of its population lived in cities and the proportion is projected to reach more than 50% by 2025.Across India, in the recent times, city after city has experienced floods. Through this paper, the author reviews urban flood events within India in recent past. This paper describes why it is important to study urban floods scenarios and what the need for this study is. It highlights the types and causes of the localized flooding as well as its impact and consequences. The study concludes the infrastructure and economic losses due to these urban events. 1 Urban Flood FLOOD is in itself abbreviates-Finally Loss Occurred after Opportunities Denied The definition of flood in engineering term-Flood is such a high stage in a water coarse i.e. river, drain or their tributary or in a water retaining body i.e. lake, pond, reservoir , seas, ocean or other low lying areas-the level at which water over flows over its banks and inundates the adjoining areas. Flood is influenced by various factors-rainfall, river-flow and tidal-surge, topography, measure of flood-control, and alterations due to infrastructural. Some floods grow and discharge gradually, while others can develop in just a few minutes and recede quickly such as flash flood. Flood events are happening for the last many years and centuries but urban floods are getting studied moderately of late (Brown, 2011). Urban flooding is caused by heavy rainfall overwhelming drainage capacity. It already has large economic and social impacts. These are very likely to increase if no changes are made to the management of urban drainage. Urban floods are a great disturbance of daily life in the city. Roads can be blocked; people can't go to work or to schools. The economic damages are high but the number of casualties is usually very limited, because of the nature of the flood. The water slowly rises on the city streets. When the city is on flat terrain the flow speed is low and you can still see people driving through it. The water rises relatively slow and the water level usually does not reach life endangering heights (Aggarwal, 2014). Then, if an intense rainfall burst occurs, causing a large amount of rain within a brief period, flash flooding may occur with little or no warning.
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Urban Floods in India
Farhat Rafiq, Sirajuddin Ahmed*, Shamshad Ahmad**, Amir Ali Khan***
* Department of Civil Engineering, Jamia Milia Islamia, New Delhi, India
** Department of Civil Engineering, Faculty of Engineering, King Abdul Aziz University, Jeddah, Kingdom of
Saudi Arabia
*** National Institute of Disaster Management, Ministry of Home Affairs, Government of India, New Delhi
Abstract: Flooding is an accumulation of water in an area either by direct rainfall irresistible to the
volume of drainage systems or a spill of huge amount of water from water bodies beyond normal limits. It
could be localized, impacting a small area or could be vast or massive, impacting very large area. Urban
flooding is caused by heavy rainfall overwhelming drainage capacity. It already has large economic and
social impacts. These are very likely to increase if no changes are made to the unplanned development
of buildings and infrastructure and poor management of urban drainage. Urban floods are a great
disturbance of daily life in the city. Urbanization in developing countries doubled from less than 25% in
1970 to more than 50% in 2006. By 2020, seven of the world’s ten largest economies will be from Asia. At
the same time, Asia in one of the fastest urbanization regions in the world. In 2000, 37% of its population
lived in cities and the proportion is projected to reach more than 50% by 2025.Across India, in the recent
times, city after city has experienced floods. Through this paper, the author reviews urban flood events
within India in recent past. This paper describes why it is important to study urban floods scenarios and
what the need for this study is. It highlights the types and causes of the localized flooding as well as its
impact and consequences. The study concludes the infrastructure and economic losses due to these
urban events.
1 Urban Flood
FLOOD is in itself abbreviates - Finally Loss Occurred after Opportunities Denied
The definition of flood in engineering term - Flood is such a high stage in a water coarse i.e. river, drain
or their tributary or in a water retaining body i.e. lake, pond, reservoir , seas, ocean or other low lying
areas- the level at which water over flows over its banks and inundates the adjoining areas.
Flood is influenced by various factors - rainfall, river-flow and tidal-surge, topography, measure of flood-
control, and alterations due to infrastructural. Some floods grow and discharge gradually, while others
can develop in just a few minutes and recede quickly such as flash flood. Flood events are happening for
the last many years and centuries but urban floods are getting studied moderately of late (Brown, 2011).
Urban flooding is caused by heavy rainfall overwhelming drainage capacity. It already has large
economic and social impacts. These are very likely to increase if no changes are made to the
management of urban drainage. Urban floods are a great disturbance of daily life in the city. Roads can
be blocked; people can’t go to work or to schools. The economic damages are high but the number of
casualties is usually very limited, because of the nature of the flood. The water slowly rises on the city
streets. When the city is on flat terrain the flow speed is low and you can still see people driving through
it. The water rises relatively slow and the water level usually does not reach life endangering heights
(Aggarwal, 2014). Then, if an intense rainfall burst occurs, causing a large amount of rain within a brief
period, flash flooding may occur with little or no warning.
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Figure 2-1: Systematic Diagram of Urban Flooding
The urban areas have been constructed upon and now it is too late to plan and tackle the problem of
flooding for such centers. Yet if the people want to save themselves from the wrath of the floods and
the government wants to avoid paying recurrent compensations to the people one of the way out is to
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construct large tanks where rain water could be stored and also to puncture the ground at several
places like it is done for rain water harvesting. This would augment the seepage capacity of the ground.
In addition a holistic drainage system for every urban complex would save many a lives, economic losses
and inconvenience due to floods. Seepage holes will prevent water-logging and the menace of the
mosquitoes.
These floodplains, often under the control of built infrastructure (i.e., levees or dams), have been
exploited worldwide for food production, reducing these benefits and making agricultural production
and associated human settlements vulnerable to flood damage. Knowledge of the spatial and temporal
patterns of flooding, as influenced by the combination of natural flood regimes and human-built
controls, is critical in maintaining the ecological functioning of floodplains (Townsend and Walsh, 1998).
Figure 2-2: Urban Water Courses
1.1 Need of Urban Flood Study
Urban flooding is significantly different from rural flooding, as urbanization increases flood risk by up to
3 times, peak flows result in flooding very quickly due to faster flow times ( in a matter of minutes), large
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number of people are affected in dense population clusters and severe economic and infrastructure loss
to industry and commerce. Urban flooding can be reduced with measures like: maintaining existing
drainage channels, providing alternative drainage paths (may be underground), control of solid waste
entering the drainage systems, providing porous pavements to allow infiltration of rainwater, etc.
(Ranger, 2011)
Climate models predict that winter rainfall will increase by 20-30% by the 2080s. Such an increase could
lead to a much larger (up to 200%) increase in flood risk. Poor natural drainage, chocking of drainage
system, extreme climate events and development in river flood plain are the main causes of the urban
flooding.
Primary
Losses
Loss of life & physical injury
Damage to buildings, contents & infrastructures
Disruptions to industrial production
Loss of, or disruptions to utility supplies
Loss of heritage or archaeological site
Secondary
Losses
Increased stress; physical & psychological trauma
Enhanced rate of property deterioration & decay
Lost value added to IND
Increased traffic congestion; disruption of flow of employees to work
Contamination of water supplies; food and other shortages
Loss of exports; Reduced national gross domestic product
1.2 Reasons of Urban Flooding
A series of storms moving over the same area can cause areal flash flooding. A muddy flood is produced
by an accumulation of runoff generated on cropland. Sediments are then detached by runoff and carried
as suspended matter or bed load. Muddy runoff is more likely detected when it reaches inhabited areas.
A lot of the sewerage and drainage network is old and its condition is unknown. They cannot cope with
the volume of water or are blocked by rubbish and by non-biodegradable plastic bags. Sewers overflow
because of illegal connections and the sewer system cannot cope with the increased volumes. As new
developments cover previously permeable ground, the amount of rainwater running off the surface into
drains and sewers increases dramatically. Developments encroach floodplains, obstructing floodways
and causing loss of natural flood storage. Continued development and redevelopment to higher density
land uses by high land costs. The proportion of impermeable ground in existing developments is
increasing as people build patios and pave over front gardens. Increased impervious areas such as roads,
roofs and paving, due to increasing development densities means more run-offs (Singh and Singh, 2011).
Some of the major hydrological effects of urbanization are: (1) increased water demand, often
exceeding the available natural resources; (2) increased wastewater, burdening rivers and lakes and
endangering the ecology; (3) increased peak flow; (4) reduced infiltration and (5) reduced groundwater
recharge, increased use of groundwater, and diminishing base flow of streams. According to natural
hydrological phenomena, due to increased impervious area precipitation responds quickly reducing the
time to peak and producing higher peak flows in the drainage channels.
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Figure 2-3: Causes of Urban Floods
1.3 Consequences of Urban Flooding
Urban Floods results in stagnation of water on roads, railway tracks and in few cases even at airports
because of the inadequate storm water drainage capacity. This results in traffic jams and traffic
diversions resulting in loss of man hours. In the events of heavy rainstorms air traffic gets diverted.
Telecommunication gets disturbed and maintenance of supply of essential commodities becomes
challenge. As communications is disrupted industrial production gets hampered. Prices of essential
commodities shoot up. During and after urban floods the immediate task is restoration of damaged
roads, railway tracks, damaged buildings (which is very common for over lived buildings) and other
structures and rehabilitation of residents from low lying areas and collapsed buildings. Damages of
assets are significant in warehouses and buildings due to flooding by storm and sewage water.
Perishable articles add to economical loss. Accidents and fire due to short circuit are also common.
Hence there are a lot of financial burdens on relief measures. There is a psychological stress as safe
returns of family members is not sure. Schools and colleges get closed. Displacement of population in
low lying areas and collapsed structures generally meets stiff resistance. Disruption in supply of essential
commodities including power supply results in unrest. Water bodies get polluted (Ganaie et al., 2013).
Waste disposal gets hampered due to traffic disruption. The stagnation of water, pollution of potable
water and accumulation of waste at dustbins result in epidemics. Accidents due to open pits, manholes
hidden under accumulated water adds to problem. As traffic gets disrupted it is challenging to assist
medical assistance.
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2 Mumbai’s Meteorological Event of 26th July, 2005
The 26 July 2005 event has been classified as ‘very heavy’ (>200 mm/day as per the criteria for rainfall
classification of IMD). The strongest rain ever recorded in India. Severe urban floods were reported from
10 cities and Mumbai was worst affected. The Santa Cruz observatory at Mumbai airport recorded 944
mm during the 24 hours ending 08:30 h on 27 July 2006 while the Colaba observatory recorded only 74
mm of rain.
Figure 3-1: Hyetograph of 26 July 2005 Rainfall- 24
H Ending 08:30 on 27 July 2005
Figure 3-2: Inundated Areas in Mumbai City Area
The Santa Cruz, heavy rainfall started at 14:30 with 481.2 mm falling in just 4 h between 14:30 and 18:30
and hourly rainfall exceeding 190 mm/h during 14:30 to 15:30. This has exceeded the rainfall record of
Cherrapunji, which has been considered the world’s wettest place. The extremely high rainfall resulted
in overflows from the already inadequate e drainage system and it was unable to drain out to the sea
because of the maximum high tide level of 4.48 m at 15:50 during the month of July 2005.
Over 60% of Mumbai was inundated to various degrees on 26 July 2005 as shown in Figure 4-2. The IMD
was unable to issue advance warnings of this event. Even when there was heavy rainfall in the northern
suburbs, the IMD was unable to monitor the rainfall and issue warnings in real time. This has been
attributed to the lack of state-of-the-art equipment like tipping bucket rain gauges with the IMD. IMD
has only two rain gauges in Mumbai and both are of the symphonic type which record data on graph
paper attached to clockwork driven drums. These are read only at 08:30 daily. The main causes of
flooding in Mumbai were .low ground levels Low ground levels, low Level of outfalls, silt of drains/nallas,
dilapidated drains, obstructions of utilities, encroachment along nallas, slums along outfalls,
urbanization, loss of holding ponds, garbage dumping in SWDs/nallas mainly in slums and increase in
runoff coefficient (Gupta, 2007.
The extreme rainfall event of 994 mm on 26 July 2005 has been a lesson for Mumbai and it has indicated
the perils of rapid development in highly concentrated urban areas. This event has resulted in Mumbai
setting up a much better response mechanism based on real-time monitoring of rainfall at 27 locations
in the city to handle recurrences of similar events in the future. The Central Water Power Research
Station, Pune is currently (2007 2008) in the process of preparing a detailed scale model for carrying
out the hydraulic model studies for the Mithi River. This model is intended to provide a basis for long-
term planning of Mumbai taking into account the impacts of climate change and sea-level rise. It would
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also help in identifying the tidal impact on the flooding and estimate the extent of inundation of low
lying areas through the progression of low and high tides.
Concurrently, another study (BRIMSTOWAD-II) with design rainfall intensity of 100 mm/h has been
commissioned by the MCGM to revise the earlier BRIMSTOWAD study (1993) which was based on
design rainfall intensity of 50 mm/h. The results of this study are intended to recommend various
structural, non-structural and pumping options for Mumbai city for the long-term and an amount of 200
m. Euros has been allocated for implementing these measures. Under the present global economy,
where major call centers and other BPO institutions are located in major cities of the developing world,
disruption in one city has roll-over effects for worldwide business; hence, we cannot ignore flooding in
any city as being just a local phenomenon (Ranger et al., 2010).
However, the present rate of urban development is likely to continue in most of the cities. If all the
resources and infrastructure are concentrated in a very small area, the cities must have a monitoring
and response mechanism to handle extreme rainfall events and other disasters. Also developments in
any major city need to be accompanied by an adequate water supply, wastewater and storm water
disposal system based on analysis of extreme rainfall events. The Mumbai experience would be helpful
for planning response strategies for other large cities to cope with similar events in the future.
3 Chennai Urban Flood of Nov Dec 2015
Chennai is crisscrossed by sluggish tributaries namely Cooum and Adhyar. Cooum flows over the core of
the city. Between the buildings of the University of Madras and Fort St. George, it drains in the ocean. It
accumulates excess from 75 tanks in its catchments within Chennai Metropolitan Area. The Adhyar river
collects surplus from about 450 tanks in its catchments, apart from overflows from the
Chembarambakkam tank. Chennai and its suburbs once boasted of over 150 small and big waterbodies.
Today the numbers of waterbodies in Chennai have been reduced to a mere 46 due to onslaught of
development. Geographically Chennai is a flat topography and absences of natural slope cease
unrestricted run off. This is a major reason for development an active scheme for storm water drainage.
The Corporation of Chennai has developed and maintains a storm water drain network of 855 km in the
city. The storm water drainage system is divided into Micro Drainage and Marco Drainage System. Past
records have shown that there were several catastrophic flooding in Chennai in 1943, 1976, 1985, 2002,
2004, 2005, 2006, 2007 and 2015 (Gupta and Nair, 2010).
Haphazard town planning, chocked drains, poor garbage management, and the rampant destruction of
mangroves, forests, and pastures have been identified as contributory factor to flood risk in Chennai.
The unprecedented rain from northeast monsoon from November to December 2015 left vast portion of
Chennai submerged. Most of the flood in Chennai are credited to depression over Bay of Bengal.
However, 2015 Chennai flood has been attributes to El Nino phenomenon (The Indian Express, 2015).
Low pressure area was amalgamated and gradually strengthened into a deep depression on 8th of
November 2015. As a result of which, there was very substantial downpour over Chennai and northern
districts of Tamil Nadu starting from 9th of Nov. (The Hindu, 2015). There was 370 mm rainfall in 24
hours. Several low lying areas were inundated by 13th Nov. In continuation, 15 to 16th of Nov, Chennai
city and neighboring areas got 246.5 mm of rain precipitation. It inundated most of the parts of the city.
In total Chennai drenched with 1049 mm of rainfall touching a return period of almost 100 years.
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Second system developed and bring heavy rainfall on 28th to 29th of November. It precipitates 490 mm
of heavy rainfall in 24 hours. It was recorded as an official disaster (zeenews.india.com, 2015).
4 Delhi Urban Floods
Delhi has a long past of flooding in Yamuna river and the Najafgarh Drain system. A steady monitoring of
floods in Delhi due to in Yamuna River was started in 1958. The danger level was fixed at 204.83m.
During the past 33 years, Yamuna River has crossed its maximum level 25 times. Since 1990, Delhi has
witnessed 6 massive floods in different years. The peak level of Yamuna was above danger level of
204.49 m in the years 1924, 1947, 1976, 1978, 1988 and 1995. The highest recorded peak of 206.92 m
was on September 27, 1988.
One of the most populous area of Delhi is to the eastern side of Delhi ridge. It includes Connaught Place,
the hub of commercial activity. Unfortunately, during storm showers, it is the site for heavy water
impounding. This may be attributed to providing concrete surface over the entire available surface on
the pretext of beautifying the area. The non-availability of sufficient recharge surface has compounded
the problem of water impounding. The drains in the Delhi were initially designed to transport excess
storm water and sewerage flow. However, due to improper layout and improper maintenance and
unsuitable geomorphological conditions, these now form pool of stagnant water in north-west and
northern parts of Delhi. As a part of solution, check dams and small lakes or ponds may be designed for
increasing ground water table and as storm water holding points. The design shall preserve the natural.
5 Noida Urban Flood Event of Flood of Sep 2010
Event of Flood of September 2010 is chosen for the testing. On Sep 9, 2010 Yamuna Rivers continues to
flow above the danger mark at 204.83 meters. Five villages of Noida was submerged on 5th Nov 2010
due to the water in Yamuna went up. One village was worst impacted. Villagers have been shifted to
community center situated on elevated ground (The Times of India, 2010).
Table 3-1: Location of Localized Flooding in Noida Due to Rainfall
1 Sector 6, Block
B
It is the location where Noida Authority is located and very prone of water logging
due to rainfall. To overcome Noida Authority has set up a permanent pump. It can
be seen clearly seen just before the entrance street of Noida Authority. There is a
cabin at the permanent pump location along with an engine setup.
Sector 6, Park
There is also one setup at the park of Sector 6. The engine is moveable.
3 Sector 12, Bock
A & H
4 Sector 11
Dhavalgiri flats near Nehru Yuva Kendra. The street of the blocks are at lower
elevation of 1m than the main road. Thus Dhavalgiri flat are always inundated
due to rainfall. It is a classic case of poor designing. The storm water drains are
also poorly designed, the slope of storm network is also poor and do not
transports water to main drain.
5 Sector 19, Block
B
6 Sector 27, Block
C
This location is also supported by a permanent pump with engine same as the
Noida Authority set up at block B of Sector 6.
Sector 34
Overall sector and its arterial streets are at lower elevation of 1mwith respect to
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the main road.
Figure 3-1: Drainage of Noida
6 Kolkata Urban Flood of 30th June, 2007
Heavy monsoon rains have caused a second wave of floods that have swept across a vast and densely
populated area of the Indian state of West Bengal. To date, it is estimated that over 15 million people
have been affected. More than 800 people are now feared dead and eight districts have been declared
flood-affected. In addition, large areas of Calcutta were flooded several times over the last two days as a
result of a high tide in the Bay of Bengal, leading to a counter flow of water upstream, with subsequent
flooding of the Hoogli River.
Although there has been a slight improvement in the northern districts of West Bengal as flood waters
start to recede, the situation in the south-east remains critical with many areas still completely cut off.
Rescue efforts continue day and night, but resources are too limited and millions of flood victims remain
stranded. The West Bengal government has started to take urgent steps to bring drinking water to the
flood-hit people in the districts. According to the local media, arrangements are being made to take
water by tanker and poly packs to remote flood-affected areas. Army helicopters continue to airdrop
food to marooned communities. Meanwhile, reports of cholera, dehydration and water borne diseases
are starting to emerge.
This second wave of floods came at a time when West Bengal was just starting to recover from the
previous wave of flooding in July and August which also struck other states including Assam, Bihar,
Arunachal Pradesh, Uttar Pradesh and Himachal Pradesh. During this period, torrential monsoon rains
and flash floods affected more than 10 million people.
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7 Bharauch, Gujarat Urban Flood of 3rd August, 2004
Bharuch district faces a number of hazards every year, which pose the threat of disaster. However, this
disaster was very new to the district. On the day of 3rd August 2004, there is a news of four person's
death due to flash flood in Karjan River. This incidence was reported to Gandhinagar. In evening at 7:00
O'clock, rain started. That rain did not stop until mid-night. Entire south Gujarat was badly affected by
the calamity of heavy rainfall. Fourth and fifth August was very painful days for Bharuch district. Water
was overflowing at the Sardar Sarovar dam on 2nd august. However, with the increasing rain activities in
the Narmada Catchment area the water level at the dam had been increased which is at 113.62 meter.
Similarly, at Garudeswar the water level was 18.62 and at the Golden Bridge 5.00 meter on 3rd August.
Bharuch City, Ankleshwar City and surrounding rural areas were affected badly because of the rainfall.
Traditional drainage in this area got blocked due to encroachment. Intensity of rainfall was very high.
Therefore, the area was unable to hold the water. This created a situation like flash floods. In short,
human obstructions to natural water flow and heavy rainfall were two prime reasons for this disaster in
Bharuch.
The heavy rainfall situation was well handled in Bharuch District. There were some problems like lack of
resources etc. District Administration tackled the situation in coordinated approach. Limitations
observed to analyze it constructively. Many new things about disaster management have been learnt.
However, the most important thing is managing the disaster in really is very difficult task for any
administrator. Hard work and devotions of disaster managers saves many lives during such disasters.
8 Conclusion
The risk of urban flooding increases during the progress of urbanization. It cause severe consequences
as they happen. A total of six urban flood cases have been reviewed and summarizes in table 2.
Table 4-1: Recent urban floods and economic losses caused
Events Consequences of the Event & Economic Losses
Chennai Urban
Flood of Nov
Dec, 2015
The losses are accumulating from Rupees 50,000 crores to 100,000 crores. The
automobile sector’s losses alone were estimated between 8,000 crore.
Maximum people died in Cuddalore locality. In Saidapet area, 2,000 huts were
submerged. 540 people dead on 10 Dec during the event. 400 people were
killed 18 lakhs were displaced.
Several suburban trains’ services were crippled. Several flights were cancelled
and many were diverted since runway was flooded.
Srinagar Event
of Sep, 2014
Srinagar received more than 550 mm of rainfall in one week. Entire city of
Srinagar was inundation by 7 8 m of flooded water.
215 people who lost their lives in the deluge. 2,600 villages were reported
affected out of which 390 villages were submerged.
The infrastructural damage is likely to cross Rs. 6,000 crore.
Hectares of ripe crop and orchards have been lost.
2008 Localized Floods in Jamshedpur, Mumbai and Bihar
2008 Urban
Flood of
Hyderabad in
Hyderabad received over 15 cm of rainfall in less than 14 hours within a span
of two days. It is second highest in four decades. Normal life came to a
grinding halt in the affected areas. With some roads under water, vehicular
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Aug traffic between twin cities remained paralyzed. Hyderabad bore the brunt of
the natural calamity with 14 people losing their lives, mostly in house
collapses. As many as 52 residential areas in and around the state capital were
inundated as twenty tanks and several major storm water drains overflowed.
Even after rains, hundreds of houses under water.
2007 Kolkata
Flood
Number of affected cities rose to 35. Kolkata was worst affected.
It is estimated that over 15 million people have been affected. More than 800
people are now feared dead and eight districts have been declared flood-
affected.
USD 680 million, including damage to infrastructure and housing and crops
and livestock losses.
2006 Surat
Uninsured loss is $2 bn. It has a diamond turnover of around Rs.130 crore ($28
million) daily, has been forced to a standstill due to heavy rainfall and high
floods. The devastating floods push Surat backwards by 25yrs.
Number of affected cities rose to 22. Surat was worst affected. 95% of Surat
under 10 to 15 feet of water for days together.
Nearly 90 per cent of the households were affected; six of the seven wards of
the city had water standing for days.
2006
Vishakhapatnam
Vishakhapatnam airport was inundated for more than 10 days.
2006 Bhopal
Event of Aug
Most of the low lying localities were inundated as water entered up to 2 3
feet in houses.
Estimated loss of more than Rs. 85 crores.
Mumbai’s
Meteorological
Event of 26th
July 2005
Rs. 450 crores loss.
At least 87 people were killed in two days of crippling rains and another 130
were feared buried in landslides. At least 419 people lost their lives including
65 killed in the several landslides. Also, 216 people died owing to the various
deluge-related epidemics.
A substantial number of buildings were damaged. 2000 residential buildings
were fully damaged.
Total collapse of the transport and communication system. Both the Mumbai
Santa Cruz airport used for commercial flights and Juhu airport used mainly
for helicopter operations had to be closed down for two days on 26 27 July,
2005. The runways were waterlogged, the terminal buildings were flooded
and crucial navigation and landing aids damaged, thus forcing over 750 flights
to be either diverted or cancelled. Both the major roads linking the northern
suburbs to the city, namely the western expressway and the eastern
expressway were submerged. Most arterial roads and highways in the suburbs
were severely affected due to water logging and traffic jams resulting from
breakdown of vehicles in deep waters. Intercity train services had to be
cancelled for over a week, while suburban trains, which are the lifeline of the
city, could not operate from 16:30 onwards for the next 36 h.
Bharauch,
Gujarat Urban
Flood of 3rd
August, 2004
Preliminary eye estimate suggested damage to 350 kms of Panchayat Roads,
costing some Rs. 9.44 Crores, necessitating roughly Rs 1 crore on immediate
repairs and Rs. 8.44 Crores on permanent repairs. Six state highways in the
district were totally blocked for traffic due to heavy water logging and flooding
in the roads. 2 bridges and 22 culverts were damaged.
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Ahmedabad-Mumbai rail and road links were disturbed due to heavy rain.
Therefore, railway traffic was disrupted in major way and many trains were
cancelled.
Communication and electricity were also affected in rural areas of Bharuch
district. Power supply was badly affected due to damage to supply lines.
9 References
Aggarwal, A., Rafique, F., Rajesh, E., & Ahmed, S. (2014). Urban flood hazard mapping using change
detection on wetness transformed images. Hydrological Sciences Journal.
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... Urban flooding has been the cause of three major categories of loss: direct damage (material destruction), indirect damage (job loss, transportation issues, infections, etc.), and social implications (König et al., 2012). The disaster disturbs the daily urban routine; damages buildings, public infrastructure, heritage, or archaeological sites; disrupts industrial production and utility supplies; enhances the rate of property deterioration and decay; disrupts the flow of employees to work due to traffic congestion; contaminates water supply sources; and brings about health problems in the city (Rafiq et al., 2016). Unlike general floods, the water level in urban floods rises slowly and seldom reaches dangerous levels (Aggarwal et al., 2016), and the effects per se are severe in terms of economic losses but minor in terms of casualties (Rafiq et al., 2016). ...
... The disaster disturbs the daily urban routine; damages buildings, public infrastructure, heritage, or archaeological sites; disrupts industrial production and utility supplies; enhances the rate of property deterioration and decay; disrupts the flow of employees to work due to traffic congestion; contaminates water supply sources; and brings about health problems in the city (Rafiq et al., 2016). Unlike general floods, the water level in urban floods rises slowly and seldom reaches dangerous levels (Aggarwal et al., 2016), and the effects per se are severe in terms of economic losses but minor in terms of casualties (Rafiq et al., 2016). It is apropos to avoid economic, social and psychological impacts of urban flooding by means of risk mitigation and management. ...
... Water logging in the region contributes to a slew of socioeconomic problems. Rafiq et al., 2016 explains and highlights the importance of urban flood studies in terms of socioeconomic impacts of the phenomenon, along with its causes and consequences in general detail. The study also explains such events taking place in various urban regions of India (Mumbai, 2005;Chennai, 2015;Delhi Urban Floods;Noida Urban Flood, 2010;Kolkata Urban Flood, 2007;Bharauch, Gujarat Urban Flood, 2004). ...
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The development of a planned township to house small industries of the informal sector which have been operating in an unauthorised and illegal manner in the capital city is an innovatory departure. NOIDA (Nes Okhla Industrial Development Area) is intended to house about 5000 industrial units. Details of NOIDA's establishment and the provisions made for it are given. Industrial and housing developments are described, and it is concluded that the scheme is progressing successfully. -D.G.Price
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The present study demonstrates the use of a new approach for delineating the accurate flood hazard footprint in the urban regions. The methodology involves transformation of Landsat Thematic Mapper (TM) imagery to a three-dimensional feature space, i.e. brightness, wetness and greenness, then a change detection technique is used to identify the areas affected by the flood. Efficient thresholding of the normalized difference image generated during change detection has shown promising results in identifying the flood extents which include standing water due to flood, sediment-laden water and wetness caused by the flood. Prior to wetness transformations, dark object subtraction has been used in lower wavelengths to avoid errors due to scattering in urban areas. The study shows promising results in eliminating most of the problems associated with urban flooding, such as misclassification due to presence of asphalt, scattering in lower wavelengths and delineating mud surges. The present methodology was tested on the 2010 Memphis flood event and validated on Queensland floods in 2011. The comparative analysis was carried out with the widely-used technique of delineating flood extents using thresholding of near infrared imagery. The comparison demonstrated that the present approach is more robust towards the error of omission in flood mapping. Moreover, the present approach involves less manual effort and is simpler to use. Editor Z.W. Kundzewicz; Associate editor A. Viglione
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Mumbai city, having an area of 437 km with a population of 12 million, came to a complete halt owing to the unprecedented rainfall of 994 mm during the 24 hours starting 08:30 on 26 July 2005. At least 419 people (and 16 000 cattle) were killed as a result of the ensuing flash floods and landslides in Mumbai municipal area, and another 216 as a result of flood-related illnesses. Over 100 000 residential and commercial establishments and 30 000 vehicles were damaged. The current paper describes Mumbai's drainage system, the details of the flooding and the measures being taken by the city to mitigate such floods in the future. The Mumbai experience would be helpful for planning response strategies for other large cities to cope with similar events in the future.
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The Earth Resources Technology Satellite (ERTS 1), launched on July 23, 1972, has been used to monitor the extent of inundation of regional floods with varying recurrence intervals. The inundated areas exhibit sharply reduced near-infrared reflectances caused by standing surface water, excessive soil moisture, and stressed vegetation, which persist up to 10–12 days after the flood peak. The amount of area affected by flooding over regions encompassing many thousands of square kilometers can be mapped definitively at 1:250,000 scale from ERTS 1 imagery in times much shorter than those required by ground-based or aircraft surveys. The ERTS 1 imagery also permits easy extension of flood mapping to areas not normally covered by more familiar survey methods. In addition to the detection of flood events, ERTS 1 can be used to map flood susceptibility indicators on the floodplain for purposes of delineating flood-prone areas.
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A variety of procedures for change detection based on comparison of multitemporal digital remote sensing data have been developed. An evaluation of results indicates that various procedures of change detection produce different maps of change even in the same environment.