Geological Survey of India
August 2000 Flood in Hyderabad City
Causative Factors and Suggestions to avoid Recurrence.
Introduction: Between 22nd and 24th August 2000, the twin cities of Hyderabad and
Secunderabad, and their environs (hereafter referred to as Hyderabad for brevity) experienced
the wettest spell in 92 years due to heavy downpour of rain. The rainfall measured 24 cm on a
single day on 24th August 2000. Many of the low-lying areas in Hyderabad which are known for
long as flood-prone were inundated. Additionally, posh localities that were raised in recent times
by providing expensive amenities were also submerged on 24th August 2000. The havoc and
human misery caused by this flood prompted Dr. H. Sarvothaman and Shri U. N. Satpathy, then
Geologists (Sr), Photo-Geology & Remote-Sensing (PGRS) Division, Southern Region,
Hyderbad, to study the (i) spatial and temporal growth pattern of urban Hyderabad during 19641998; (ii) geological and geomorphological factors that cause floods in Hyderabad; and (iii)
causes of this flood hazard. The study was also aimed at identifying areas in Hyderabad
unsuitable for urban development, and to suggest remedial measures to avoid recurrence of
floods in the existing urban limits of Hyderabad. This remote-sensing study was carried out
using three tools namely, (i) 1:25,000 scale aerial photographs of 1964-65; (ii) 1:25,000 scale
toposheets of 1974; and (iii) IRS-lC PAN imagery (1:10000 scale) of 1998. Geo-environmental
map of Hyderabad (bringing out geomorphology too) was prepared (and appended with this
report) by interpretation of a mosaic of 1:25000 scale aerial photos. This map was compared
with toposheets and PAN imagery to examine the pattern and progressive urban growth of
Hyderabad in the last four decades.
Geology & Growth Pattern of Hyderabad City:
Hyderabad City was built more than 400
years ago to support a population of 600,000. It is a land-locked city characterized by gently
undulating terrain, punctuated by granite hillocks and mounds. Several dykes intrude the
granite, and some of these dykes form linear ridges. Many of these hills and ridges (for example
in Banjara Hills, Shaikpet, Malkajgiri and Addagutta areas) are intervened by low-lying areas
and also drained by minor streams. Musi River and its tributaries drain the area. There is a
bounded tank by name Husain Sagar roughly in the centre of the city; several streams and
rivulets (identified in aerial photos, but currently they are wastewater drains) bring water and fill
Husain Sagar.
The area of Husain Sagar has considerably reduced due to urbanization.
Besides Husain Sagar tank, in the past there were innumerable tanks that served as drinking
water source to the city and partly as irrigation tanks. But most of these tanks have given way
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Geological Survey of India
for development of human habitats in the modem city of Hyderabad and its urban
agglomeration, which in the year 2000 supported over 6,000,000 population. Tropical semi-arid
weather characterizes the region which receives an average of 80 cm rain during southwest
monsoon.
Growth of industries and information technology provided right atmosphere in
Hyderabad for influx of population and substantial investment in real estates. Steady population
growth in Hyderabad had necessitated conversion of vast agricultural fields laden with water
resource into human habitat. A virtual scramble for space within the vantage locations in the
urban limit for commercial, bureaucratic, educational, healthcare, industrial, entertainment and
human activities has resulted in disorganized growth of several parts of Hyderabad, besides
development of several locations unsuitable for urban life. The human misery caused due to
the flood in August 2000 can be cited as the best example for the unsustainable urban growth in
India.
August 2000 Flood: Though this flood had not claimed many human lives, loss of movable
and immovable properties was reported. Several weak buildings collapsed due to incessant
torrential rains and innumerable automobiles were damaged due to floods and the debris
transported by the floodwaters. Strangely, water level in Musi River was not considerable, an
uncommon feature during flood in Hyderabad. This indicated that the rainfall was not heavy in
the catchment area of Musi River and its main tributaries. Besides, when Hyderabad
experienced unprecedented rain, major areas beyond about 60 km radius, such as the districts
of Nalgonda and Mahabubnagar remained dry due to scanty or lack of rainfall. Some of the
worst affected areas due to flood in Hyderabad were Masab Tank, Vijayanagar Colony, Ashok
Nagar, Gandhi Nagar, Adarsh Nagar, Domalguda, Nallakunta-Barkatpura, Yousufguda,
Musapet, Sanjeeva Reddy Nagar, Begumpet, Saroornagar and Ramantapur. Most of the
residential colonies in these areas have come up as multi-storied buildings in recent times;
therefore, better civic facilities are expected to prevail in these areas. Contrarily, several recently
raised residential colonies were also inundated. In contrast, areas with well established,
centuries-old human habitats were safe in August 2000 flood ravage.
Causes of Flood:
1. The flood-affected areas in Nallakunta and Barkatpura areas are the residential colonies
raised in the recent past by blocking the active channel of a prominent tributary of Musi
River. The existence of this tributary has been inferred from the aerial photographs of
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Geological Survey of India
the year 1964, and is brought out in the map. The heavy floodwater, which always
follows the active channel of the natural surface drainage such as the stream and
tributary, was blocked by the new habitats constructed in these areas. Blockage of
natural stream leads to inundation of the habitats raised along its course.
2. The peripheries of many water tanks that existed in Hyderabad in mid-I960s, were
converted into residential areas. As the necessity of land suitable for the residential
purposes kept mounting during the population boom period in Hyderabad, the basic
norms to be followed during the urban development have been violated. This can be
exemplified by the fact that several tanks and reservoirs that existed in the past have
given way to habitats in recent times. One such blatant violation of the urban
development norms is conversion of a water tank known as Masab Tank, situated at the
southern foothill limit of Banjara Hills, into currently a thickly populated residential-cumcommercial area. Further, the downstream side of this tank has been totally converted to
residential areas such as Vijaya Nagar Colony and Shanti Nagar. Similar is the situation
at the Hyderabad-Vijayawada National Highway near Saroornagar. Thus, the active
channels of streams that existed on the downstream sides in these areas or colonies
have totally disappeared. The concrete structures built in these areas have been
blocking the natural surface drainage on the downstream side of Masab Tank and
Saroornagar Tank during rainy season and floods, and therefore they get inundated by
flood waters in the event of rainfall that takes place even for about five to six hours
continuously. The August 2000 flood was also one such instance of inundation.
3. The August 2000 flood of Hyderabad cannot be considered as a result of the Nature's
fury. It starkly exposes the deficiencies in planning of urban habitats in growing cities.
Paradoxically, when Hyderabad was lashed by 24 cm of rain in 24 hours in August 2000,
the adjacent districts of Mahabubnagar and Nalgonda were under the grip of drought-like
or dry weather conditions due to scanty rainfall. The surface runoff from the Hyderabad
floodwaters has in no way benefited the depleted groundwater system or soil water in
the adjacent dry lands or in Hyderabad. The floodwaters got quickly transported as
surface runoff into Musi River. The August 2000 flood of Hyderabad was an aberration in
the weather pattern caused due to a local low pressure. Yet, demarcation of low-lying
areas, natural drainage on the surface of the prospective residential areas and
measures to allow the floodwaters to drain out as natural surface runoff would certainly
avert disasters such as the August 2000 flood of Hyderabad.
Recommendations to avert flood hazard in urban areas: This flood hazard is a pointer to the
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Geological Survey of India
fact that a lot needs to be done for urban development in the case of Hyderabad in particular
and all Indian cities in general. A set of recommendations is made for application of geological
inputs to the development of urban centres and metropolises. They are summarized as follows:
1. There is a need to apply study on the geomorphology of the areas within and adjoining
urban centres and the prospective areas which are planned to be brought within the urban limits
in respect of all cities, towns and metropolises. Geomorphology has be a made as a mandatory
input parameter while considering creation of new residential colonies by the urban /
metropolitan development authorities. Low-lying areas with slopes, and natural drainage
channels and surfaces should be avoided for developing them into residential areas.
2. If residential areas are already created in low-lying areas with slopes, and by
obstructing the natural surface drainage, walled ducts or canals have to be built in such a way
that the surface runoff is diverted into these ducts or canals. That would avoid flooding of the
residential areas, since the floodwaters would be channeled through the canals or ducts. This
sort of artificial drainage to modify natural surface drainage is prevalent in western countries. If
the urban land in Indian towns and metropolises is so scarce that there is no alternative site for
residential colonies than the low-lying areas, similar walled ducts or canals should be provided
to the prospective low-lying areas that are contemplated to be developed into habitats.
3. Most of the streams, canals and artificial drainage system which are provided in the
cities and metropolises in India are totally choked during flood times causing inundation of vast
areas. The materials that choke the surface drainage are construction wastes (mortar, sand and
brick-pieces) and residential wastes. The municipal authorities should enforce strict laws
prohibiting the builders from dumping construction wastes in public places.
4. Vast quantities of plastics -- such as plastic bags and bottles -- choke the underground
drainage and the canals that are provided to channellise the urban wastewater. During
monsoon these plastics also choke the wastewater channels and as a result the floods are
caused. Plastics being not biologically degradable, they remain in the urban drain system for
several decades, and therefore cause long-term environmental degradation besides flooding
due to choking of the drains. Therefore, the government should necessarily place ban on the
use of plastics, or alternatively, find out ways for safe disposal of the plastics as is done in the
western countries. It may not be out of context to mention at this juncture that several States in
the Himalayan belt -- Himachal Pradesh and Uttarakhand -- have banned the use of plastics in
these States with a view to avoid choking of the Himalayan rivers and their tributaries. Similar
ban should be imposed by the other States so that the peninsular rivers are saved from
extinction.
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Geological Survey of India
5. One of the major causes of the urban floods is the total filling up of the ponds, tanks
and reservoirs which are major receptacles of floodwater, by the silt and sand transported
during floods. De-silting operations for these inland water bodies should be taken up periodically
to ensure that they receive the floodwaters. Besides averting the urban floods, these water
bodies serve as slow percolators of water to the groundwater system, thereby augmenting the
groundwater resource. The tanks, ponds and reservoirs, especially within the urban limits,
should be preserved at any cost and saved from encroachments by habitats.
6. The urban authorities need to realize that the geomorphological considerations -- such
as demarcation of low-lying areas and areas geologically unsuitable for human habitats -- are
vital to the urban development. Therefore, before developing new areas for residential
purposes, the urban development authorities should necessarily get these prospective areas
studied by authorized geological institutions and get official clearance from them as geologically
suitable for human habitats. The agencies capable of giving such advice need to offer
assistance to the urban development authorities on this.
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Geological Survey of India
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