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Urban floods in Bangalore and Chennai: risk management challenges and lessons for sustainable urban ecology


Abstract and Figures

A number of major cities and towns in India reported a series of devastating urban floods in the recent decade. Mumbai flood 2005 followed by other major cities of South Asia like Dhaka, Islamabad, Rawalpindi also suffered with urban flooding. Census 2001 figured 285 million people in 35 metro cities of India, and is estimated to cross 600 million with 100 metro cities in 2021. Regional ecological challenges coupled with climatic variability are noted to aggravate flood risks and impact on affected communities. Urban flooding was primarily a concern of municipal and environmental governance, has now attained the status of ‘disaster’, which has drawn the attention of environmental scientists and disaster managers. Challenges of urban flooding in terms of drainage and flood mitigation including structural and non-structural measures and key issues of urban ecology in two major metropolitan cities of India – Bangalore and Chennai, have been studied. Risk management challenges in the context of land-use, city and population growth, wetland degeneration, waste disposal have been discussed.
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CURRENT SCIENCE, VOL. 100, NO. 11, 10 JUNE 2011
The authors are at the National Institute of Disaster Management, IIPA
Campus, New Delhi 110 002, India.
*For correspondence. (e-mail:
Urban floods in Bangalore and Chennai: risk
management challenges and lessons for
sustainable urban ecology
Anil K. Gupta* and Sreeja S. Nair
A number of major cities and towns in India reported a series of devastating urban floods in the re-
cent decade. Mumbai flood 2005 followed by other major cities of South Asia like Dhaka, Islama-
bad, Rawalpindi also suffered with urban flooding. Census 2001 figured 285 million people in 35
metro cities of India, and is estimated to cross 600 million with 100 metro cities in 2021. Regional
ecological challenges coupled with climatic variability are noted to aggravate flood risks and im-
pact on affected communities. Urban flooding was primarily a concern of municipal and environ-
mental governance, has now attained the status of ‘disaster’, which has drawn the attention of
environmental scientists and disaster managers. Challenges of urban flooding in terms of drainage
and flood mitigation including structural and non-structural measures and key issues of urban eco-
logy in two major metropolitan cities of India Bangalore and Chennai, have been studied. Risk
management challenges in the context of land-use, city and population growth, wetland degenera-
tion, waste disposal have been discussed.
Keywords: Bangalore, Chennai, cities, floods, urban ecology, wetlands.
Cities and floods
‘IF there could be such a thing as sustainable develop-
ment, disasters would represent a major threat to it, or a
sign of its failure.’1 In 2000, 37% of Asia’s population
lived in cities and the proportion is projected to reach
more than 50% by 2025. Unfortunately, the majority of
Asian mega-cities and other urban localities occupy
hazard-prone land. In the period 1994–2004 alone, Asia
accounted for one-third of 1562 flood disasters. Urbani-
zation in developing countries doubled from less than
25% in 1970 to more than 50% in 2006 (ref. 2). It is
estimated that at least 13 cities of the world that are prone
to natural hazards will have a population in the 10–25
million range, with nine of them in Asia. In 2001, there
were 285 million people in India residing in 35 metro
cities (cities having a population of above 1 million).
This is estimated to exceed 600 million by 2021 in over a
100 metro cities as the trend is on a rise.
Recent events highlighted the man-made causes respon-
sible for recurring and prolonged floods in South Asian
cities like Dhaka, Mumbai, Chennai, Bangalore, Ahmeda-
bad, Surat, Patna, Jamshedpur, Rawalpindi and Islama-
bad. Floods result from the overflow of land areas,
temporary backwater effects in sewers and local drainage
channels, creation of unsanitary conditions, deposition of
materials in stream channels during flood recession, rise
of groundwater coincident with increased stream flow,
and other problems3. Disaster management the worldover
is undergoing a paradigm shift from approach to ‘response
and relief’ to ‘prevention and mitigation’4. The call for a
mix of resistance and preparedness for resilience towards
flood risk in cities depends on management of urban eco-
logy5, including land use, water bodies, waste disposal,
etc. Major implications of urbanization are the following6,7.
Heat island effect
Surface and atmospheric temperatures are increased by
anthropogenic heat discharge due to energy consumption,
increased land-surface coverage by artificial materials
having high heat capacities and conductivities, and the
associated decreases in vegetation and water-pervious
surfaces, which reduce surface temperature through
Loss of aquatic ecosystems
Urbanization has telling influences on the natural
resources such as decline in the number of water bodies
and/or depleting the groundwater.
CURRENT SCIENCE, VOL. 100, NO. 11, 10 JUNE 2011 1639
Figure 1. Causes of urban floods in India32.
Figure 2. Map of India showing location of Bangalore and Chennai.
Loss of drainage capacity
Unplanned urbanization has drastically altered the drain-
age characteristics of natural catchments, or drainage
areas, by increasing the volume and rate of surface run-
off. Drainage systems are unable to cope with the in-
creased volume of water and are often encountered with
blockage due to indiscriminate disposal of solid wastes.
Disasters are events of environmental extremes which
are inevitable entities of this living world, and linked to
every component of the ecosystem. Urban flooding has
been recognized as a ‘disaster’ only after the Mumbai
flood in 2005. As revealed in Figure 1, the interaction of
flood causes in urban environment indicates significance
of urban ecology in disaster risk reduction8. The present
article discusses the flood challenges and mitigation
issues for two important metro cities of India, viz. Banga-
lore and Chennai (Figure 2). The aim of the study was to
understand the problems of increasing flooding inci-
dences in urban areas and related contexts of urban deve-
lopment and ecological issues. Data of secondary origin
have been collected and interpreted in the context of
flood risks and urban management. The article also
conveys wider issues and lessons for flood challenges in
Indian cities and towns.
Bangalore is located almost equidistant from both the
eastern and western coasts of the South Indian peninsula.
The mean annual rainfall is about 880 mm with about 60
rainy days a year. Bangalore is known as the ‘IT city’ or
‘silicon valley’ of India due to the presence of several
software companies. It is the fifth largest city of India
with population of about 7 million, located around
100 km from the Kaveri River. There has been a growth
of 632% in urban areas of Greater Bangalore across 37
years (1973–2009). Encroachment of wetlands, flood-
plains, etc. is causing floodway obstruction and loss of
natural flood storage in Bangalore4.
The gap in the installed capacity of the wastewater
treatment system (450 MLD) as against the estimated
generation of domestic water (700 MLD) is evident. Ban-
galore has 134 flood-prone areas (Table 1). The City
Corporation has identified these areas after a survey of
critical locations which are prone to recurrent flooding.
However, some areas in the city face the brunt of the
rains more than the others and are more prone to flooding.
In 2005, flooding had worsened by unauthorized deve-
lopments along three lakes. Choked drains led to residential
CURRENT SCIENCE, VOL. 100, NO. 11, 10 JUNE 2011
areas being inundated, and traffic was severely affected.
Thousands of office-goers were stranded on the city’s
waterlogged roads. Schools in the city were closed
and several apartment complexes were flooded. Water
entered some office buildings, including one of the
offices of India’s third largest software exporter, WIPRO.
The flood left hundreds of people homeless and ailing
due to various health problems and environmental chal-
Built-up area (16% in 2000) has now increased to 23–
24% in the metropolitan area of Bangalore. There are 542
slums located in the jurisdiction of Karnataka Slum
Clearance Board (218) and Greater Bangalore City
Corporation (324), out of which 310 are undeclared set-
tlements according to 2001 Census. Temporal analysis of
water bodies indicated a sharp decline of 58% in Greater
Bangalore attributed to intense urbanization process, evi-
dent from 466% increase in built-up area from 1973 to
2007. Analysis revealed (Figure 3; Table 2) decline of
wetlands from 51 in 1973 (321 ha) to merely 17 (87 ha)
in 2007. The number of water bodies reduced from 159 to
The lakes of the city have been largely encroached for
urban infrastructure. As a result, in the heart of the city
only 17 good lakes exist as against 51 healthy lakes in
1985. According to a study6, the water bodies of the city
have reduced from 3.40% (2324 ha; 5742.7 acres) in
1973 to just about 1.47% (1005 ha; 2483.4 acres) in
2005, with built-up area during the corresponding period
increasing to 45.19% (30,476 ha; 75,307.8 acres) from
27.30% (18,650 ha; 46,085.2 acres).
Figure 4 shows unplanned settlements with very poor
drainage. Enforcement of land-use laws and guidelines/
plans has been observed to be poor. Field surveys (during
July–August 2007) showed that nearly 66% of lakes are
Table 1. Top five flood-prone areas identified in Bangalore city
Ejipura/Koramangala : National Games Village area
BTM Layout : I and II stage area
Shankarappa Garden : Magadi Road area
Brindavan Nagar : Mathikere area
Ambedkar College : Airport road area
Figure 3. Land-use changes, 1973–2007.
sewage-fed, 14% surrounded by slums and 72% showed
loss of catchment area6. Also, lake catchments were used
as dumping yards for either municipal solid waste, con-
struction residue or building debris.
Bangalore city has a 180 km long primary and secon-
dary storm-water drainage system, which often fails to
take the load of the rains due to silt and garbage causing
blockage. A provision of Rs 45 million has been made for
the flood-management fund with 12 squads on call, of
which six are rain and flood relief squads; 20 personnel
have been assigned in each squad. The Jawaharlal Nehru
Urban Renewal Mission (JNURM) project was launched
in December 2005 and Bangalore has been allocated a
budget for the next six years.
Topographically plain terrain with few isolated hillocks
in the southwest, Chennai is bounded on the east by the
Bay of Bengal and on the remaining three sides by the
Kanchipuram and Tiruvallur districts. Chennai receives
on an average approximately 1300 mm of rainfall per
year most of this (~800 mm) falls during the northeast
(NE) monsoon in the months of October through Decem-
ber. The city is situated at approximately 13°N lat. and
80°E long. Chennai city currently encompasses an area of
172 sq. km, and the metropolitan area adds almost
400 sq. km of urban agglomeration to this figure. Chennai
faces a number of risks, partly climate-related, but also
human-induced such as waste disposal, water contamina-
tion and lack of drinking water, suburban sprawl and
mismanagement in urban planning7.
Due to the plain terrain Chennai lacks natural gradient
for free run-off. This necessitates an effective storm-
water drainage system. The sewage system in Chennai
was originally designed for a population of 0.65 million
at 114 litres per capita per day of water supply; it was
further modified during 1989–1991, but is now much
below the required capacity. Cooum and Adyar rivers in
Figure 4. Slums and high-density poor settlements.
CURRENT SCIENCE, VOL. 100, NO. 11, 10 JUNE 2011 1641
Table 2. Loss of water bodies
Bangalore city Greater Bangalore
Year No. of water bodies Area (ha) No. of water bodies Area (ha)
SOI 58 406 207 2342
1973 51 321 159 2003
1992 38 207 147 1582
2002 25 135 107 1083
2007 17 87 93 918
SOI, Survey of India, topographic maps (published in 1973); Source: Ramachandra and Uttam Kumar6.
Figure 5. Growth of Chennai since 1923 (from Gupta and Nair8).
Chennai city are almost stagnant and do not carry enough
water, except during the rains. These rivers play a major
role during floods, collecting surplus water from about 75
and 450 tanks in their respective catchments. Chennai
municipal area has a network of canals and channels
within its boundary. Buckingham canal, originally a
navigation channel and waterway till 1954, now serves
only as a drainage channel.
The physical growth of Chennai from 1923 to 1971 is
shown in Figure 5. The population has grown by eight
times in the period 1901–2001 and per hectare population
density has increased from 80 to 247. Chennai has a large
migrant population from other parts of Tamil Nadu and
other parts of the country, accounting for 21.57% of the
Chennai population in 2001. There are three major water
courses (Cooum, Buckingham Canal and Adyar) in Chen-
nai city and the banks of all the areas encroached (Figure
6). Slums (number recorded to be 30,922) have developed
here without basic amenities and are subjected to flood
every year. They often pollute the water courses, thus
worsening the health situation.
Several catastrophic floods in Chennai in the past
(1943, 1976, 1985, 1996, 1998, 2005, 2010) were caused
by heavy rain associated with depression and cyclonic
storms, leading to floods in major rivers and failure of
drainage systems. Chennai was severely flooded due to
heavy rains (16–20 cm, attributed to a trough of low pres-
sure from the Gulf of Mannar to the Southwest Bay off
the Tamil Nadu coast) during 30 October–2 November
2002. Residential areas became ‘islands’ and were cut-off,
paralysing life, services and trade, including transport,
communication, etc. On 5 November 2004, heavy rainfall
(6 cm within 24 h or less) caused flooding and waterlog-
ging in many areas, inundating most of the slums9. A
deep depression over the Bay of Bengal brought 42 cm
rainfall in around 40 h during the NE monsoon of 2005.
Several floods were reported during 2006, 2007 and
2008. Closing of schools due to flooding every year is
common in many parts of Chennai. The Chennai Munici-
pal Corporation has identified 36 localities as flood risk
hotspots (Figure 7).
Since the beginning of the 20th century, Chennai has
witnessed a steady deterioration of and decease in water
bodies and open spaces (Figure 7). It is estimated that in
Chennai city more than half of the wetlands have been
converted for other uses. Chennai had about 150 small
and big water bodies in and around the city, but today the
number has been reduced to 27. The important water bodies
include Adyar Estuary, Adambakkam lake, Ambattur
lake, Chitlapakkam lake, Ennore creek, Korattur swamp,
Madhavaram and Manali Jheels, Pulicat lake, Vyasarpadi
lake, besides Buckingham Canal, Coovum and Otteri nul-
lah. Ownership of water bodies is scattered among various
government departments and is the root cause for lack of
proper management. The Protection of Tanks and Evic-
tion of Encroachment Act, came into effect on 1 October
2007. However, there has been lack of implementation of
this law.
CURRENT SCIENCE, VOL. 100, NO. 11, 10 JUNE 2011
The green cover reduced rapidly across the city between
1997 and 2001. In some wards almost 99% of the green
cover has been replaced by non-vegetative development.
As a result, the water-holding capacity of the city’s surface
has gone down drastically. The reduced city’s surface water-
holding capacity combined with the augmented imperme-
able surface increased the peak flow up to 89% from
Figure 6. Degradation of Madhuravayal lake.
Figure 7. Flood risk hotspots in Chennai metropolitan area (Source:
Chennai Metropolitan Development Authority, www.cmdachennai.
1997 to 2001 in some of the wards. Increased surface run-
off and reduced retention capacity of the land cover
almost stopped the groundwater recharging processes in
the city. Slum impact and environmental degradation of
Cooum river is shown in Figure 8 a and b (ref. 10).
Meteorologically, there is no major upward or down-
ward trend of rainfall during 200 years, and a decrease in
the last 20 years with a contrast record of increasing
floods has been experienced in Chennai. Causes of in-
creased flooding identified are:
(a) Uncontrolled urban sprawl and loss of natural
drainage. Drainage channels have been blocked and urban
lakes filled and encroached, canals degraded and polluted,
heavily silted and narrowed. A 1994 survey revealed
waterways contamination and anaerobic digestion led to
sludge accumulation causing hydraulic hindrances.
(b) Inadequacy of storm-water drainage system and
lack of maintenance. The city has only 855 km of storm
drains against 2847 km of urban roads. Plastic and poly-
thene constituents to the storm-water stream along with
poor or no maintenance aggravates flood.
(c) Increase in impervious surfaces. Paving of road-
sides, parks and open areas causing flood severity and
conditions for drought to follow.
(d) Lack of coordination between agencies. Lack of a
unified flood control implementing agency that integrates
Figure 8. a, A residential area backing onto the Cooum river33.
b, Cooum river narrowed by encroachments10.
CURRENT SCIENCE, VOL. 100, NO. 11, 10 JUNE 2011 1643
the functions of the Corporation, Development Authority,
Public Works Department, Slum Clearance Board, Hous-
ing Board, etc.
All the waterways in Chennai are considered to be pol-
luted, but the Cooum river and Buckingham Canal are
widely recognized to be the worst. A Government-funded
Flood Alleviation Scheme was launched in 1998, with a
cost Rs 3000 million, focused mainly on structural meas-
ures. Adequacy of flow in the arterial drainage system,
removing impediments, safeguard, against tidal and flu-
vial flooding, relocation and rehabilitation of encroachers
were the main objectives. Cleaning of certain waterways
and lakes was also undertaken under packages 2 and 3 of
the scheme. Chennai City River Conservation Project was
launched in 2000 to improve the waterways, with an esti-
mated outlay of Rs 17,000 million. The Master Plan
1992–1993 incorporated Madras Metro Flood Relief/
Storm Water Drainage study outcomes in the form of
structural and non-structural measures. Funds under
JNURM project have been envisaged for implementation
of underground sewerage schemes and detailed project
reports are being developed. Thiru Vi Ka Industrial
Estate has been proposed for rehabilitation and upgrading
of sewerage system.
Discussion and lessons
Urban flooding is significantly different from flooding in
rural areas as urbanization results in impermeable catch-
ments causing flood peaks by up to three times5. Conse-
quently, flooding occurs quickly due to faster flow times
(in a matter of minutes). As a reference to discuss the
growing flood menace in other cities in India, including
Bangalore and Chennai, the lessons of the July 2005
floods in Mumbai are important to mention. The flood of
2005 was truly a disaster as it receded only after seven
weeks and affected 20 million people. The floods killed
1200 people and 26,000 cattle. It destroyed more than
14,000 homes, and damaged more than 350,000; about
200,000 people had to stay in relief camps. The agricul-
tural sector was heavily hit as 20,000 ha of farmland lost
the topsoil and 550,000 ha of crop was damaged11. Un-
precedented rainfall in one day was certainly one major
cause of the floods; with a 24 h rainfall figure that
exceeds the monthly average of 30 years. The rainfall
data show that within a period of 18 h, the precipitation
level rose to 944 mm in the suburban area, with maxi-
mum rain between 14.30 and 17.30 h on 26 July, a stag-
gering 380.8 mm in 3 h. Between 14.30 and 20.30 h
maximum rainfall of 647.5 mm was recorded, coinciding
with the time people were trying to reach their homes
from their work places.
The Mumbai flood of 2005 was followed by incidences
of urban flooding as a regular phenomenon in many
Indian cities, not only metros but in many towns as well.
Floods were reported recently in cities like Ahmedabad,
Bhopal, Bangalore, Calcutta, Chennai, Delhi, Gorakhpur,
Hyderabad, Surat, Rohtak and Kurukshetra due to a com-
bination of many factors like heavy or patchy rainfall,
dam-water release or failure, inadequate drainage sys-
tems, blockade, housing in floodplains and natural drain-
age or riverbed and loss of natural flood-storages sites. It
demonstrated on how unplanned, rapid urban develop-
ment has stretched the natural ecosystems in and around a
city to its limits, and made disaster from natural flood
hazards inevitable12. Lessons drawn from the studies are
summarized here on critical issues for future research and
planning interventions.
Urban drainage
Some of the major hydrological effects of urbanization13
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 ground-
water, and diminishing base flow of streams. Vegetation
plays a vital role in evapotranspiration and soil-water
storage components of this balance. The driving force
behind the biodrainage concept is the consumptive water
use of plants14. The role of biodrainage in controlling
waterlogging and secondary salinization is important in
urban flood mitigation15.
Urbanization has marked effects on basin run-off in
terms of higher volume, higher peak discharge, and
shorter time of concentration3,16. As the risk of flooding
increases with climate change, so does the importance of
the major drainage systems. New design approaches,
which explicitly design roads to act as drains, can radi-
cally reduce the duration of flooding. Litter management
is critical to the management of urban drainage sys-
tems17,18. Often the best investment in drainage is better
handling of solid waste to prevent systems from becom-
ing rapidly blocked with debris16,19. Chennai witnesses
425 new vehicles on the road every day causing pressure
for motorable and parking space. A total of 42.6 million
people living in 8.2 million households have been living
in slums of 640 cities/towns spread across 26 states and
Union Territories, according to the 2001 Census. The
slum population constitutes 4% of the total population of
the country. Interestingly, the share of slums in urban
population has grown in major metro-cities compared to
smaller ones.
Flood impacts and risk assessment
Given the high spatial concentration of people and values
in the cities, even small-scale floods may lead to consid-
erable damage. In extreme cases urban floods can result
CURRENT SCIENCE, VOL. 100, NO. 11, 10 JUNE 2011
in disasters that set back urban development by years or
even decades. Velocity is also a major factor in determin-
ing per cent damage, with velocity floods capable of
causing building collapse even in relatively shallow
waters. Climate change is likely to amplify the challenge
of pest and disease control, as new ecological niches
appear that may sustain exotic pathogens and disease vec-
tors20. For example, flooding may become more frequent
in some geographic locations with climate change and
can affect health through the spread of water-borne dis-
eases17. Flood risk assessment is an essential part of flood
risk management. The ‘urban’ approach includes a specific
urban-type set of economic, social and ecological flood
risk criteria, which focus on urban issues: population and
vulnerable groups, differentiated residential land-use
classes, areas with social and health care, but also eco-
logical indicators such as recreational urban green spaces.
Vulnerability assessment21 represents, an important con-
tribution to decrease and control of land damage caused
by natural hazards, as it helps in strategies that limit
weakness by integrating flood risk into urban develop-
Ecological aspects
‘All ecological projects (and arguments) are simultane-
ously political–economic projects (and arguments) and
vice-versa. Ecological arguments are never socially neu-
tral 23’. As work on disasters since the nineties increas-
ingly focused on issues of human vulnerability and
resilience, a more integrative approach has gained
favour24. Hazards are now defined as ‘human ecological
interaction that can generate disaster’25. Urban ecosys-
tems are the consequence of the intrinsic nature of humans
as social beings to live together6,26. Ecosystem function-
ing is guided by abiotic steering variables related to
hydrology, water quality and sediment load. These can be
used as primary indicators of ecosystem condition
and changes to them are first-order impacts. Floods and
storms are an integral part of the ecosystem dynamics and
have both positive and negative effects on human well-
Urban meteorology has come to require much more than
observing and forecasting the weather of our cities and
metropolitan areas17. Risks must be considered through
continuing assessments of science, technology and appli-
cation uncertainties, as well as in the costs and benefits
associated with each of the urban issues and the proposed
actions to mitigate adverse hazards or impacts17. Abrupt
variability and increased uncertainties about rainfall
pattern, periods, days and amount, and risk of weather
extremes as an impact of global climate change28 aggra-
vated by ecological and anthropogenic factors as local
climate actors8 pose ever-increasing risk of flood disaster
or waterlogging-led epidemics in urban areas.
Many of the water bodies, including man-made wet-
lands/lakes and natural depressions have disappeared due
to human-induced succession filled with waste, and
development or slum encroachments5. Urban wetlands in
India have reduced to approximately 30% during the last
50 years. Wetlands hold the run-off generated from heavy
rainfall, water discharge from reservoirs or channels or
snow-melt events. They reduce the possibility of flooding
in downstream or moderate flooding to some extent, de-
pending on the magnitude of run-off. Wetland vegetation
slows down the flow of flood water29. Wetlands reduce
the need for expensive engineering structures29. Under-
standing by many of the professional engineers working
on urban issues is not up to date with environmental
aspects and they generally look for structural solutions
which degrade the environment creating too many imper-
vious areas and thereby increasing the temperature, flood-
ing, pollution, etc.30. An integrated approach, therefore,
needs to combine watershed and land-use management
with development planning, engineering measures, flood
preparedness, and emergency management in the affected
lowlands, while taking into account the social and eco-
nomic needs of communities in both the highland source
areas, and also the lowland flood-prone areas31.
1. Hewitt, K., Excluded perspectives in the social construction of
disaster. Int. J. Mass Emergencies Disasters, 1995, 13(3), 317–
2. UNDP-India, Panel discussion on urban floods in India (Back-
ground note). UNDP-India and NDMA, Government of India,
2010, E-circulation.
3. Allen, A. and You, N., Sustainable Urbanization: Bridging the
Green and Brown Agendas, University College London, London,
UK, 2002.
4. Gupta, A. K., Nair, S. S., Chopde, S. and Singh, P. K., Risk to re-
silience: strategic tools for disaster risk management. NIDM,
ISET-US, US-NOAA and DFID, International Workshop Proceed-
ing Volume, NIDM, New Delhi, 2009, p. 116.
5. Gupta, A. K. and Nair, S. S., Comparative study of urban flood
challenges in three cities of India. In Proceedings of International
Hydrology Programme Conference on Flood Resilient Urban
Environment, UNESCO, Paris, 25–27 November 2009.
6. Ramachandra, T. V. and Uttam Kumar, Wetlands of greater
Bangalore, India: automatic delineation through pattern classifiers.
Electron. Green J., 2008, 1(26);
7. Ramachandra, T. V. and Uttam Kumar, Land surface temperature
with land cover dynamics: multi-resolution, spatio-temporal data
analysis of Greater Bangalore. Int. J. Geoinform., 2009, 5(3), 43–53.
8. Gupta, A. K. and Nair, S. S., Flood risk and context of land uses:
Chennai city case. J. Geogr. Reg. Plann., 2010, 3(12), 365–372.
9. Menon, J., Chennai grapples with floods. The India Express,
Chennai, 25 December 2005 (from the web).
10. Srinivasan, R. K., White foam: the Chennai riverbed does not have
space to breath. Down to Earth, February 2008 (from the web).
11. Arambepola, N. M. S. I., Effective strategies for urban flood risk
management, Asian Disaster Preparedness Center, Bangkok, 2007;
12. SAPRDPI, South Asia Disaster Report, Practical Action, South
Asia Programme and Rural Development Policy Institute, Paki-
stan, 2005;
CURRENT SCIENCE, VOL. 100, NO. 11, 10 JUNE 2011 1645
13. UNESCO, Hydrological effects of urbanization: studies and
reports in hydrology, United Nations Educational, Scientific and
Cultural Organization, IHP-18, Paris, France, 1974.
14. Greenwood, E. A. N., Klein, L., Beresford, J. D. and Watson, G.
D., Differences in annual evaporation between grazed pasture and
Eucalyptus species in plantations on a saline farm catchment.
J. Hydrol., 1985, 78, 261–278.
15. Chhabra, R. and Thakur, N. P., Lysimeter study on the use of
biodrainage to control waterlogging and secondary salinization in
(canal) irrigated arid/semi-arid environment. Irrig. Drain. Syst.,
1998, 12, 265–288.
16. Ramachandra, T. V. and Varghese, S., Exploring possibilities of
achieving sustainability in solid waste management. Indian J.
Environ. Health, 2003, 45(4), 255–254.
17. OFCMSSR, Urban Meteorology: Weather Needs in the Urban
Community, FCM-R22-2004, Officer of the Federal Coordinator
for Meteorological Services and Supporting Research, Maryland,
USA, 2004, p. 18.
18. Rustam, R., Karim, O. A., Ajward, M. H. and Jaafar, O., Impact of
urbanization on flood frequency in Klang river basin, ICAST
2000, Faculty of Engineering, University Kebangsaan, Malaysia,
2000, pp. 1509–1520.
19. Gunne-Jones, A., Land use planning: How effective is it in reduc-
ing vulnerability to natural hazards 2003; available at http://www.
20. Meganck, R. A., Disaster management of urban water systems un-
der climate change. UNESCO Institute for Water Education.
Refresher Seminar Paper, Bangkok, November 2009.
21. Turner, B. L. et al., A framework for vulnerability analysis in sus-
tainability science. Proc. Natl. Acad. Sci. USA, 2003, 100(14),
22. Barroca, B., Bernardara, P., Mouchel, J. M. and Hubert, G., Indi-
cators for identification of urban flooding vulnerability. Nat. Haz-
ards Earth Syst. Sci., 2006, 6, 553–561.
23. Harvey, D., The nature of environment: the dialectics of social and
environmental change. In Real Problems, False Solutions (eds
Miliband, R. and Panitch, L.), Merlin Press, London, 2006, pp. 1–51.
24. White, I. and Howe, J., Flooding and the role of planning in Eng-
land and Wales: a critical review. J. Environ. Planning Manage.,
2002, 45, 735–745.
25. Mitchell, J. K., Human dimensions of environmental hazards:
complexity, disparity, and the search for guidance. In Nothing to
Fear: Risk and Hazards in American Society (ed. Kirby, A.), Uni-
versity of Arizona Press, Tucson, 1990, pp. 131–175.
26. Sudhira, H. S., Ramachandra, T. V. and Bala Subramanya, M. H.,
City profile: Bangalore, Cities, 2007, 124(4), 379–390.
27. Mirza, M. M. Q., Warrick, R. A., Ericksen, N. J. and Kenny, G. J.,
Are floods getting worse in the Ganges, Brahmaputra and Meghna
basins? Environ. Hazards, 2001, 3, 37–48.
28. Kundzewicz, Z. W. and Schellnhuber, H.-J., Floods in the IPCC
TAR perspective. Nat. Hazards, 2004, 31, 111–128.
29. Ramsar, Wetland: Values and functions fact sheet, 2004; on.alerts/action_alerts5.htm (accessed
on 12 January 2011).
30. Tucci, C. E. M., Urban Flood Management: Course Notes, 2007,
World Meteorological Organization (,
Cap-Net International Network for Capacity Building in Integrated
Water Resources Management (, and
Global Water Partnership, GWP-SAMTAC.
31. Calder, I. R. and Ailward, B., Forest and floods: moving to an evi-
dence-based approach to watershed and integrated flood manage-
ment. Water Int., 2006, 31(1), 1–13.
32. Gupta, A. K. and Dhar Chakrabarti, P. G., Flood risk and mitiga-
tion challenges in cities Indian case studies project. Disaster
Dev., 2009, 3(1), 1–14.
33. Bunch, M. J., An adaptive ecosystem approach to rehabilitation
and management of the Cooum River environmental system in
Chennai, India. Ph D thesis, University of Waterloo, Ontario, Canada,
ACKNOWLEDGEMENTS. We thank the Executive Director of
National Institute of Disaster Management (NIDM), New Delhi for re-
search grant and inputs on aspects of urban governance and planning.
Inputs from Dr T. V. Ramachandra, IISc, Bangalore, and Drs T. Sunda-
ramurthy and L. Ramadurai, CPREEC, Chennai, as part of city teams
of the NIDM project are acknowledged.
Received 12 January 2010; revised accepted 30 March 2011
... This paper examines the intertwinement of flood risk and unregulated urban expansion processes based on in-depth research in Accra's sprawling periphery. Existing research suggests that urban flood risk intersects with large-scale land-use changes associated with urban expansion processes (Duy et al., 2018;Gupta & Nair, 2011;Lee & Brody, 2018;Remondi et al., 2016;Saraswat et al., 2016;Vachaud et al., 2019). Urban expansion has become a persistent feature of contemporary urban transformations in Africa, where sprawling new residential developments incessantly spread into surrounding peri-urban and rural areas (Africapolis, 2022;Atlas of Urban Expansion, 2020). ...
... Urban flood risk has been linked with large-scale land-use changes associated with urban expansion processes, namely, the increase in impervious surfaces and the reduction of vegetation cover and natural water retention areas, which may combine to reduce ground infiltration and increase surface run-off rates within urban watersheds (Duy et al., 2018;Gupta & Nair, 2011;Lee & Brody, 2018;Remondi et al., 2016;Saraswat et al., 2016;Vachaud et al., 2019). Harmful development practices may, for instance, alter or impede natural water flows by narrowing or blocking rivers and streams, encroaching on wetlands and clogging of channels by sediments and waste (Amoateng et al., 2018;Douglas, 2017;Shatkin, 2019). ...
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Urban flood risk is significantly shaped by ground conditions and the built environment , which are constantly modified and transformed by human actions. This paper examines the intertwinement of flood risk and unregulated urban expansion processes in three selected sites in Accra's expanding periphery. All three sites have been included in Accra's urban extent since the 1990s, but differ with regard to the timing of development and socioeconomic characteristics of residents. The research illuminates how flood risk is produced and "built-in" to the urban fabric through widespread practices associated with unregulated urban expansion processes, especially the persistent encroachment on water retention areas, wetlands and riparian zones and the highly fragmented provision of transport infrastructure in emerging residential areas in the periphery. Such harmful development practices are neither confined to homebuilders from poorer segments of the urban population nor spatially concentrated in low-income areas. The research highlights how the actions and inactions of a wide range of social groups and actors engaged in urban land administration and development contribute to flood risk in various ways, making flooding an increasingly alarming issue of citywide concern. Different stakeholders highlight fragmented urban governance as an underlying root cause for the obstruction of sustainable land and water management. Overall, the study calls for a more robust recognition of spatial planning and transport infrastructure provision in flood risk mitigation and highlights the urgent need for planning and governance practices that challenge the existing fragmentation of urban governance systems.
... In the United States, nearly 45% of people who died during the flood were inside vehicles (Jonkman and Kelman 2005). The severity of floods, especially in urban areas, increased substantially in recent times, which can be attributed to unplanned development in low-lying areas, blockage of the drainage system, and changing rainfall patterns due to climate change (Tingsachali 2012; Gupta and Nair 2011). The major cities on the bank of rivers near the coast are more vulnerable to frequent and extreme floods due to changing global climatic conditions. ...
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In the current study, the one-dimensional/two-dimensional (1D/2D) coupled hydrodynamic model is used for the development of flood hazard maps for the frequently flooded coastal urban floodplain of the Surat city, India. The releases from the Ukai dam and tidal levels at the Arabian Sea are considered as upstream and downstream boundary conditions, respectively. The floodplain roughness was estimated using the existing land use land cover (LULC) classification, and the performance of the developed coupled hydrodynamic model was evaluated against the past flood data of year 2006 and 2013. The flood frequency analysis was carried out for peak inflow into the Ukai reservoir, and subsequently, the design flood hydrographs for different return periods have been developed. Finally, the simulated model output has been used to develop multi-parameter flood hazard maps defining the stability of people, vehicles, and buildings. More than 80% of the entire coastal urban floodplain of the Surat city is submerged during 100-year return period flood, with West and North zone of the city being the worst affected regions. Out of the total flooded area, nearly 20% area is under significant hazard for adults. The 27% area offers instability hazard to large four-wheel drive vehicles, whereas 14% area is affected with moderate to high hazard for buildings. The instability index for specific vehicle types is dominated by floating of small and large cars over 90% of the flooded area. Further, the combined hazard maps revealed that 14% of the flooded area is under very severe hazard category, posing a threat to the stability of people, vehicles, and buildings. The developed hazard maps will work as an effective non-structural measure for local administrative agencies to minimize the losses and better future planning.
... Furthermore. water pollution International Journal of Water Governance 9, 1-22 occurs from flood impacting the drainage channels and creation of unsanitary conditions from deposition of waste materials in the drains (Gupta & Nair, 2011). Urban runoff affects the water quality as shown by Girija et al., (2007) in their study of the Bharalu catchment and stream. ...
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Flooding is a critical issue affecting many countries worldwide with severe consequences on the lives of their residents. In this paper, we conduct a case study of the flood management policies of India by evaluating their implementation in six Indian states that are affected by recurrent flooding every year. The states selected have major cities located near water bodies and have experienced flooding leading to deaths and displacement besides slowing down economic and community development. We evaluate how each of the states align their policies to the national level disaster management guidelines for flood management. We find that for policies established at the state level, implementation within the various regions can vary with some urban areas going beyond the state and national guidelines. We find that not all Indian states follow the established national guidelines, and this poses questions on the challenges on having uniform flood management policies for addressing a complex issue.
Flooding is by far the most natural hazards, affecting the greatest number of people on the planet. Severe floods in urban areas have become more common in recent years as a result of uncontrolled urbanisation and climate change, and this trend is expected to continue in the coming years. Climate change is constantly changing the weather pattern. There has been rise in annual average temperature, which has affected the variation of sea-land surface temperature. Thus, leading to change in the monsoon pattern over Indian ocean and Indian Sub-continent. Now-a-days, it is usually experienced with increase in number of summer days and lesser winter days. The monsoon system of the Indian Subcontinent is greatly affected by Indian Ocean and due to changing pattern, shorter rainfall period having higher intensity rainfall for very short period of time leading to occurrence of extreme rainfall events over isolated areas. This leads to the condition of sudden disaster like situation in urban agglomeration where due to poor water drainage structure the situation has been occurring more frequently. The results identify 18% of total area is liable to urban floods out of which 10% area indicates high risk, 50% area shows medium risk and remaining 34% area falls under low risk of flooding. Thus, making an alarm to an urban man-made disaster due to heavy rainfall in urban areas. Due to human involvement in the environment, there have been a dominance over the natural components leading to change in rainfall pattern.KeywordsClimate changeExtreme rainfallUrban floodsPopulationLand use/land cover patterns
Natural hazards occur due to the interactions between extreme natural events and anthropogenic activity that have the potential to inflict damage, disruption, death, or injury. The escalating anthropogenic influence on the natural processes of the fluvial stream has polluted the water, altered the transit capacity due to the increase in suspended loads, and there by leading fluvial hazards. River-related natural hazards are broadly categorized as (a) flooding and (b) lateral erosion. Floods are natural disasters that occur either due to waterlogging and spreading induced by heavy rains or due to collapse of hydraulic structures caused by rising water levels in the river channel. The flood management process in India is extremely complicated due to the influence of numerous socio-hydro climatological elements such as climate change, sea level rise, and socioeconomic dynamics. In this article, the unique geomorphic patterns of three major recent flood-affected sites in India such as Uttarakhand flood in Upper Ganga Valley in June 2013, Kashmir flood in Jhelum River occurred in September 2014, and Chennai flood happened on December 2015 were briefly explained. Consequently, the activities of Indian flood management agencies were also discussed with a focus on current flood management techniques. River bank erosion has long-term implications for human life leading to economic crisis and forced relocation of victims. The alterations in the flow of rivers due to bank erosion have a profound impact on river ecology. The impacts of river bank erosions in four zones of India viz., (a) North West region, (b) central India and Deccan region, (c) Brahmaputra region, and (d) Ganga (Ganges) region were presented in this study.KeywordsHydrological hazardsFloodsNDMA
Nature-based solutions, such as reviving blue-green infrastructure (BGI), for climate adaptation in cities have been gaining global attention. In the case of India, the rapid urbanization since the end of the twentieth century has exacerbated the impact of climate change at significant environmental, social, and economic costs. Coastal cities in India commonly face climate change related hazards of flooding, rise in sea level, and urban heat islands. This article has assessed the usefulness of scientific information and community knowledge in planning, reviving, and maintaining BGI to make it a successful climate adaptation practice in coastal cities. The existing waterways and water bodies in India's coastal cities are a network linked to the green infrastructure that has been altered by sprawling urbanization. In response to Sustainable Development Goals 11 and 13, the cities of Kochi and Chennai have begun a process of recovering their BGI for greater resilience. This research has detected a shift in the social and administrative perception of BGI as a valuable resource for climate adaptation in recent times. Actions in backwaters and canals, promoted by Chennai and Kochi municipal corporations, present new steps toward mainstreaming adaptation of BGI into the local regulatory framework.
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Accelerated rise in sea levels due to changing climate threatens the communities located in the low-lying coastal regions. Small-scale fishing communities such as artisanal fishing communities are vulnerable to the risk of sea-level rise. Climate services are considered to be effective instruments to communicate such risks and enhance the capacity of local communities. However, the application of climate services to build capacities of artisanal fishing communities remains sparse. In this context, this study attempted to address the risk of rising sea levels and building capacity of artisanal fishing communities of Ennore region in Chennai situated on the east coast of India, as a case study. The study has addressed the following research questions: What sea-level rise risk information is required? How should it be communicated effectively? and how efficiently climate services can be utilized to enhance the capacities of communities to rising sea levels? BASIEC coastal climate service framework methodology has been adopted. Sea-level rise risk campaign and adaptation workshops were served as climate service platforms to create awareness through narratives and visualization techniques as risk information, communication and education strategies. By adopting participatory techniques such as citizen science and pair-wise ranking methods, the study has identified and prioritized community-based adaptation strategies to sea-level rise. As a climate service, this case study provides a model to communicate the sea-level rise risk and build capacities of artisanal fishing communities in adaptation decision-making. The approach and methodology of this study are valuable for facilitating climate services to empower coastal communities.
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Mullite is a combination compound of alumino-silicate, found very rarely in nature. During the last two decades, mullite becomes crucial for classical and modern ceramics due to its favorable properties. In this present investigation, mullite ceramic was fabricated using industrial waste (fly ash) through the gel casting process. The green body is made up of two batch compositions with varying raw materials followed by sintering at 1300C. Fly ash powder characterization was done by PSD, XRF, XRD, and SEM. Finally, the sintered samples were analyzed by XRD and SEM. The XRD peak and SEM micrographs confirmed that mullite crystals have formed in the batch composition of MC2.
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In progress toward smart city environments, which revolves around improving city services, sustainability, and citizen’s quality of life; information and communication technology (ICT) can be influential. The development and consolidation of IoT-based smart city applications are supported by software platforms. However, there are few environmental, social, and technological challenges before these platforms that the ICT community must overcome. Due to these difficulties, a variety of scenarios in various situations for IoT-enabled smart cities have been considered. This chapter throws light on the major issues with the smart city project and the measures taken in the favor of these challenges. Also, in this chapter, work is proposed which demonstrates the use of drones in the surveillance of the cities thus ensuring a safer smart city. A smart city offers reliable e-services, a higher quality of living, and serves the needs of its residents daily. This is part of India’s ambitious “Digital India 2030” plan to develop smart cities across the country, where the Internet of Things (IoT), modern networks, smart solutions, and, ICT in the event of natural disasters are all important to achieve this objective. Residents of smart cities produce a vast amount of data as a result of their behavior daily, which, if gathered and processed, could aid smart cities in being more effective, people-friendly, clean, and stable.
The Ukai Dam is built on the Tapi River in Gujarat, mainly for agricultural activities, power generation, and flood control. However, large potential energy from the Ukai Reservoir would impose a risk of sudden breach of containment leading to loss of life and property at Surat city in the downstream area. This paper is deemed to provide a dam-break analysis of the Ukai Dam to generate a breach hydrograph and flood map as a result of the dam-break event under piping and overtopping failure. The process of collecting and preparing data, estimating breach parameters, developing a one-dimensional and two-dimensional unsteady flow model in HEC-RAS 5 software, performing dam-break analysis, and mapping of flood propagation are outlined in this paper. The result shows that the peak discharge of the dam-breaking flood hydrograph is 237759 m3 s−1 with a maximum velocity of 9.18 m s−1, and a maximum water surface elevation is 35.68 m. The computed hydraulic parameters through simulation can be useful for preparing flood hazard risk maps and emergency action plans.
Conference Paper
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The severe impacts of floods, whether it happens as a result of climate change or otherwise, are most likely to be in urban areas where people, resources and infrastructure are concentrated. This will affect not only the city's populace but also its industries, commercial ventures, livelihoods and ultimately lower the potential for investment. The concept of the safer city is encouraging for returns on long-term investments, business continuity and public safety. This paper will present some of the strategies used in Asia to keep the city safe and functioning in spite of the potential for flood hazards.
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The purpose of this paper is to review and respond to the preceding five articles in this special issue. My principal charge is to look at the authors’ approaches to answering the question of “What is a disaster?” and respond to their considerations. In doing this, I have outlined a variety of what I believe to be “excluded” perspectives in these formulations of what constitutes disasters.
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Wetlands are the most productive and biologically diverse but very fragile ecosystems. They are vulnerable to even small changes in their biotic and abiotic factors. In recent years, there has been concern over the continuous degradation of wetlands due to unplanned developmental activities. This necessitates inventorying, mapping, and monitoring of wetlands to implement sustainable management approaches. The principal objective of this work is to evolve a strategy to identify and monitor wetlands using temporal remote sensing (RS) data. Pattern classifiers were used to extract wetlands automatically from NIR bands of MODIS, Landsat MSS and Landsat TM remote sensing data. MODIS provided data for 2002 to 2007, while for 1973 and 1992 IR Bands of Landsat MSS and TM (79m and 30m spatial resolution) data were used. Principal components of IR bands of MODIS (250 m) were fused with IRS LISS-3 NIR (23.5 m). To extract wetlands, statistical unsupervised learning of IR bands for the respective temporal data was performed using Bayesian approach based on prior probability, mean and covariance. Temporal analysis of wetlands indicates a sharp decline of 58% in Greater Bangalore attributing to intense urbanization processes, evident from a 466% increase in built-up area from 1973 to 2007.
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Evidence is presented to show that there is a growing disparity between public percep- tion and scientific evidence relating to the causes of floods, their impacts, and the benefits of mitigation measures. It is suggested that this disparity has arisen through the extensive promotion of certain land uses and engineering interventions by vested interest groups in the absence of any effective dissemina- tion of the scientific evidence which may allow a contrary view. It is believed that this disparity may have resulted not only in the wastage of development funds (possibly to the extent of tens of billions of dollars per year) on unachievable targets, but also in the unwarranted blame of upland communities whose practices have generally had only marginal impacts on downstream flooding. It is recognized that the interaction of floods and society is a highly complex subject. What is recognized, with some certainty, is that simplistic and populist land management solutions, such as oft-advocated solutions involving commercial afforestation programs, cannot ever represent a general solution and will, in most situa- tions, have at best marginal benefit and at worst negative impacts. Similarly, structural engineering interventions, although in the short term providing protection to flood-affected communities in one area may have the effect of transferring the problem downstream and may also introduce other unforeseen adverse environmental and economic impacts. An improved approach to watershed and flood manage- ment is proposed that integrates watershed and land-use management in the highlands with land-use planning, engineering measures, flood preparedness, and emergency management in the affected low- lands while taking into account the social and economic needs of communities in both the highland, often source areas, and also the lowland flood-prone affected communities. This approach should be based on our best available scientific knowledge of the causes and the environmental, social, and economic impacts of floods and the environmental, social, and economic effects of engineering interven- tions.
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India witnessed increased flooding incidences during recent past especially in urban areas reportedly since Mumbai (2005) as a mega disaster. Other South Asian cities like Dhaka, Islamabad, Rawalpindi, besides many other cities in India, are also reportedly been affected by frequent floods. Flood risk in urban areas are attributed to hazards accelerated by growth in terms of population, housing, paved-up areas, waste disposal, vehicles, water use, etc. all contributing to high intensity – high load of runoff. Reduced carrying capacity of drainage channels is also a key concern. Haphazard growth of low-income habitations and un-organised trade added to challenge. Spatial dimensions of all these flood factors are often characterised by land-use and changes. Chennai, a coastal mega-city is fourth largest metropolis in India, has a history of over 350 years of growth. Meteorologically there is no major upward or downward trend of rainfall during 200 years, and a decrease in last 20 years with a contrast record of increasing floods have been experienced. Analysis of land-use changes over the temporal and spatial scale has been undertaken for Chennai city in order to understand the patterns on green-cover, built-up area and consequences on hydrological settings. Land-use issues like decreased natural areas, loss of water bodies, encroachment of river/streams and other drainage channels, uncontrolled multiplication of built-up areas, have been identified as contributory factor to flood risk in Chennai. The paper discusses flood risk reduction and management strategies in urban context with example of the Chennai city and draws attention of land-use planners and disaster management experts to integrate their efforts for better and sustainable results.
Bangalore is experiencing unprecedented urbanisation in recent times due to concentrated developmental activities with impetus on IT (Information Technology) and BT (Biotechnology) sectors. The concentrated developmental activities has resulted in the increase in population and consequent pressure on infrastructure, natural resources, ultimately giving rise to a plethora of serious challenges such as urban flooding, climate change, etc. One of the perceived impact at local levels is the increase in sensible heat flux from the land surface to the atmosphere, which is also referred as heat island effect. In this communication, we report the changes in land surface temperature (LST) with respect to land cover changes during 1973 to 2007. A novel technique combining the information from sub-pixel class proportions with information from classified image (using signatures of the respective classes collected from the ground) has been used to achieve more reliable classification. The analysis showed positive correlation with the increase in paved surfaces and LST. 466% increase in paved surfaces (buildings, roads, etc.) has lead to the increase in LST by about 2 ºC during the last 2 decades, confirming urban heat island phenomenon. LSTs’ were relatively lower (~ 4 to 7 ºC) at land uses such as vegetation (parks/forests) and water bodies which act as heat sinks.
Daily evaporation (including evaporation from the ground surface) from grazed annual pastures and from five species of Eucalyptus in two farm plantations was measured at regular intervals for a year. Leaf area of trees and pasture, and rainfall interception and stem flow by trees, were also measured. The trees were in their seventh year after germination. The site was a first-order catchment that had developed a saline seep midslope after the felling of the prior forest. One plantation was upslope, the other was immediately above the seep. The work is part of a salinity reclamation study based on increased evaporation through the strategic use of trees.Annual evaporation from pastures was 390 mm regardless of position in the landscape. Annual evaporation from trees upslope was 2300 mm for Eucalyptus maculata and 2700 mm each for E. globulus and E. cladocalyx. Values at midslope were 1600 mm for E. wandoo, 1800 mm for E. leucoxylon and 2200 mm for E. globulus. Expressed as a proportion of annual rainfall (680 mm), annual evaporation was 0.6 for pasture and ranged from 2.4 to 4.0 for trees while interception by trees ranged from 0.16 to 0.36, and stem flow was less than 0.02. Annual evaporation, but not interception, was correlated with leaf area. The application of these findings is discussed.We conclude that the planting of discrete areas of trees has the evaporation potential to assist in reclamation of saline farm land in the southwest region of Australia and that some species are much more effective than others.
In this paper the authors raise some important questions about the extent to which planning is fostering an environment susceptible to flooding. They argue that severe UK flooding incidents in recent years should result in the government re-examining the planning system to ensure relevancy and effectiveness in dealing with such problems in the future. They identify where the current policy and practice weaknesses lie in planning to limit both flood source and flood impact areas and suggest ways in which the government and the profession could take remedial steps to increase local and regional sustainability.
Recent floods have become more abundant and more destructive than ever in many regions of the globe. Destructive floods observed in the 1990s all over the world have led to record-high material damage, with total losses exceeding one billion US dollars in each of two dozen events. The immediate question emerges as to the extent to which a sensible rise in flood hazard and vulnerability can be linked to climate variability and change. Links between climate change and floods have found extensive coverage in the Third Assessment Report (TAR) of the Intergovernmental Panel on Climate Change (IPCC). Since the material on floods is scattered over many places of two large volumes of the TAR, the present contribution - a guided tour to floods in the IPCC TAR – may help a reader notice the different angles from which floods were considered in the IPCC report. As the water-holding capacity of the atmosphere grows with temperature, the potential for intensive precipitation also increases. Higher and more intense precipitation has been already observed and this trend is expected to increase in the future, warmer world. This is a sufficient condition for flood hazard to increase. Yet there are also other, non-climatic, factors exacerbating flood hazard. According to the IPCC TAR, the analysis of extreme events in both observations and coupled models is underdeveloped. It is interesting that the perception of floods in different parts of the TAR is largely different. Large uncertainty is emphasized in the parts dealing with the science of climate change, but in the impact chapters, referring to sectors and regions, growth in flood risk is taken for granted. Floods have been identified on short lists of key regional concerns.