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Environment
West Bengal Needs
Better Disaster Management
by VK
Joshi
 Natural or
anthropogenic phenomenon, that pose a threat to human lives and property
are called as hazard. The nature is always at work. Therefore, a river
keeps eroding, mountain slopes under given conditions move down to cause
landslides, earth trembles causing earthquakes etc.
West Bengal lying on the east of the country has a peculiar disposition.
It is a coastal state as well as a state with highland like Darjeeling
and the state has the vast Ganga-Brahmaputra plains too. Like any other
state, West Bengal too has its share of natural and man made hazards
like cyclones, floods, droughts, landslides, subsidence, occasional
earthquakes, pollution of surface and subsurface water etc.
It is therefore, clear that the state of west Bengal needs a disaster
preparedness and mitigation plan. Sankar Kumar Nath and Kiran Kumar
Singh Thingbaijam of Department of Geology and Geophysics and Debasis
Roy of Department of Civil Engineering, IIT, Kharakpur published a
detailed review of the situation in west Bengal and have suggested
remedial measures in the April issue of the Current Science.
The natural environmental hazards which most commonly affect the life of
the state include floods, cyclones and storm surges, droughts and land
subsidence. Earthquakes and tsunamis are the hazards that affect the
state once in a while. It is better to be informed rather than remain
blissfully ignorant and get lashed by the nature's ire.
G.R. Brakenridge and his colleagues from Dartmouth Flood Observatory,
Hanover, USA have compiled digital records of major deluges in various
parts of the globe. As per that between 1985 and 2007 West Bengal has
faced 23 major floods. Irony is that the rivers submerging vast tracts
of habitation and agriculture lands have origins outside the state.
Sankar and his colleagues state that 55.8% of the region is susceptible
to floods. It means more than half the area of the state is prone to
deluges.
Kolkata, Hooghly, Howrah, Paraganas, Midnapore, Burdwan, Birbhum,
Jalpaiguri, Cooch Behar, Malda, Murshidabad and Darjeeling areas seem to
face the worst ever year. The recent trends of floods are more alarming
because densely populated Kolkata gets marooned during monsoons. During
September and October 2006 the deluge was so powerful in Kolkata that
2000 people had to be evacuated. In 2007 the flood scenario was so grim
that 51 people lost their lives and 3.2 million people were affected by
floods record Sankar and his co-researchers.
Reading about Kolkata raises questions that why the metros on the coasts
are becoming prone to floods. Whether Mumbai or Kolkata, scenario
remains pretty bad. One of the main reasons is the lack of proper
drainage. Near coast the ground tends to become more flat, as such
excess water does not flow smoothly. Drains constructed for the purpose
are not able to cope up with the rain water because of lack of proper
maintenance/remain choked by the city's garbage. Apartments and housing
colonies have erupted on the natural path of excess rain water, flooding
is but natural.
A strategic plan for flood hazard in urban areas therefore must include
construction, restoration or improvement of drainage and removal of all
human encroachment along the river banks. Since this is an on going
process highest priority therefore should be given to search, rescue and
evacuation process. Quick and correct damage assessment would enable
speedy restoration and rehabilitation in terms of physical, economic and
social aspects recommend Sankar et al.
The next worst natural hazard that hits W. Bengal almost every year is
the cyclone. One of the worst cyclone hit Sagar Island killing 50,000
people and 1,00,000 cattles in March 1833. Again in October 1854 a 12 m
high surge hit the coasts and water levels rose in Kolkata and
neighborhood. Nearly 50,000 people perished in this cyclone. The cyclone
of 1864 caused floods on 13 km on either side of Hooghly River killing
80,000 people. While the Independence struggle was on in 1942 15,000
people perished in W. Bengal due to cyclone. In the later years call it
providence or improved communication systems that the number of deaths
has become less though the loss of property has shown a rise. Main
reason for this could be more and more people settling close to the sea!
A better preparedness can further reduce the losses says Sankar et al.
Stable cyclone shelters on high grounds, fast communication systems and
rapid distribution of information about impending cyclone to keep the
society alert are important measures. Land use plans need a detailed
look, because permitting permanent structures like hotels on cyclone
prone shores are open invitations to tragedy.
As already stated a part of the state of W. Bengal is hilly tract of
Darjeeling District. Landslides and mountain slopes are almost
synonymous. In 1968, floods in the Darjeeling area destroyed vast areas
of W. Bengal and neighboring state of Sikkim by unleashing about 20,000
landslides and killing thousands of people, report Sankar et al. These
slides were caused by a heavy downpour ranging from 500-1000 mm in three
days. Such incidents have a return period of 100 years claim the
meteorologists. The impact of the rains was such that the
Darjeeling-Sikkim road was breached at 92 places and the road transport
was totally disrupted.
Though such heavy landslides are not a routine but a few landslides do
affect the road communication each year and often lives are lost too.
One of the root causes is the construction activity on the hill slopes.
Material on the mountain slopes lies in an angle of repose and remains
in a state of balance. If a construction activity, undercutting of
mountain 'toe' by a swift river or an unusually high rainfall can
trigger a downward motion of the material. Gravity aids to the
phenomenon and the mountain slides, killing people and destroying
property in its wake.
Landslide is one hazard that can be predicted in advance. But before
doing so, detailed information is required. Using satellite data and
Geographical Information System various thematic layers describing the
geological characteristics, water conditions, material properties,
topographical inclinations, seismic activities, prediction of soil
behavior under load, etc. are considered for the thematic integration to
achieve hazard zonation says Sankar et al. These zones categorize high,
medium and low hazard zones and the municipal authorities can
accordingly allow the construction activity suitable for the particular
zone.
Alluvial terrains everywhere face droughts due to less than required
rains and agricultural droughts due to lack of moisture in the soil.
Bankura, Purulia and Bribhum districts of W. Bengal face droughts of
these types frequently. Outlining the steps required for managing
droughts Sarkar and his co-workers say drought management and planning
involves water supply augmentation and conservation (e.g. rainwater
harvesting techniques), expansion of irrigation facilities, effective
dealing with drought, and public awareness and education. Transport and
communication links are a must to ensure supply of food and other
commodities during and just after a drought. Successful drought
management requires community awareness on the mitigational strategies,
insurance schemes for farmers, crop contingency plans, etc.
It is an irony that the management techniques outlined by the
researchers are well known to the district authorities and plans are
accordingly made. But it hurts to realize that actual relief to a
drought hit farmer does not reach. What he gets is a pittance. The
relief work needs stricter supervision by the people's representatives
and the administration both.
Though, it experiences earthquakes at a relatively low frequency of
seismic hazard zonation map, West Bengal by virtue of its geological
disposition has areas falling in varying earthquake hazard zones. As per
the map of Bureau of Indian Standards W. Bengal lies in seismic zones
II-IV, corresponding to peak ground acceleration (PGA) of 0.1, 0.2, and
0.25 (1 g = 980Gal) respectively. Purulia in south west part of W.
Bengal has is in the lowest hazard zone II While northern and
southeastern parts of Kolkata metropolis lie in zone IV. In addition
Darjeeling, North and South Dinajpur., parts of Jalpiguri and Coochbehar,
North and South Paganas and Malda also fall under zone IZ. Eastern parts
of Jalpaiguri and Coochbehar fall in zone V inform Sankar et al. A
considerable part of W. Bengal falls in the zone III. For example
districts of Kolkata, Murshidabad, Birbhum, Bardhaman, Hooghly, Howrah,
Nadia, Bankura and East and West Midnapur fall under zone III.
The Himalayan ranges in the north and northeast are prone to
earthquakes. A few earthquakes are also reported from the Bengal Basin
or the Fan areas, that is where the Ganga and Brahmaputra rivers dump
their loads in the Sea. The Great Assam Earthquake of 1897 had caused
widespread damages in Kolkata.
Earthquake is one hazard that strikes without warning. For more than a
century the area may remain calm and placid and suddenly one day
(generally night) the buildings begin to tremble and often the results
are disastrous. Thus earthquake microzonation studies in all urban
agglomerates of West Bengal are need of the time. Mere studies won't
help the maps produced should be implemented in letter and spirit and
building plans need to be approved according to the anticipated
acceleration expected at a given place. Periodic reassessment of
microzonation is essential because the information of today on the map
might change as more data pours in.
Tsunami is another natural hazard for which the coastal areas of W.
Bengal have to remain geared up. Only plus point it that the Ganga-Meghna
mega fan (that is the fan shaped gently sloping feature formed by the
sediments deposited by these two rivers in the sea and the Sunderbans
act as a buffer for the Tsunami. It is time that the government stops
meddling with the ecology of the mangroves and stops developing it as an
industrial belt. The mangroves are not merely a rich biodiversity
hotspot but also act as a natural buffer for hazards like tsunamis and
storm surges.
Land subsidence in the coal mine areas of Raniganj is another local
hazard but needs a careful attention. It is more of man made hazard,
because the mined area if not properly protected leads to subsurface
collapse and subsidence. Urbanization of Raniganj and similar areas
needs to be done with the help of latest technologic innovations like
laser tomography to know the stability of the sub-surface.
Pollution of the atmosphere due to carbon spewing chimneys of the
industries and vehicular exhaust, pollution of surface water bodies
through urban and industrial effluents etc are well known hazards and
they can be controlled through active social awakening. Anthropogenic
hazards are easy to deal with if the government and the society work in
tandem.
Sankar et al have lucidly outlined the hazards that frequent West
Bengal. For a holistic outlook of disaster management they recommend (a)
collaborations of different organizations, (b) local participation, (c)
inputs from scientific and research institutions, (d) awareness and
promotion, and (e) delivering appropriate regulations and policies.
Addressing multiple hazards, such as usage of multi-hazard maps,
synergized methodologies, etc. is recommended to be more pragmatic.
The media has a very positive role to play in pre-hazard mitigation.
Both the print and the electronic media should take a lead in informing
the readers/viewers about the impending hazards. Awareness about the
hazards prepares the population better to face them.
June 8, 2008
Image under license with
Gettyimages.com
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