Flood Problem and Management in South Asia

212 Pages·2003·5.15 MB·English

by  O. N. Dhar

FLOOD PROBLEM AND MANAGEMENT IN SOUTH ASIA
Flood Problem and
Management in SouthAsia
Edited by
M. MONIRUL QADER MIRZA
Adaptation and Impacts Research Group (AIRG), Institute for Environmental
Studies (IES), University ofToronto, Canada
AJAYADIXIT
Nepal Water Conservation Foundation (NWCF), Kathmandu, Nepal
AINUN NISHAT
IUCN - World Conservation Union, Dhaka, Bangladesh
Reprinted from Natural Hazards,
Volume 28 No. 1, 2003
SPRINGER-SCIENCE+BUSINESS MEDIA, B.V.
A c.I.P. Catalogue record for this book is available from the Library of Congress.
ISBN 978-90-481-6197-3 ISBN 978-94-017-0137-2 (eBook)
DOI 10.1007/978-94-017-0137-2
Printed on acid-free paper
All Rights Reserved
© 2003 Springer Science+Business Media Dordrecht
Originally published by Kluwer Academic Publishers in 2003
Softcover reprint of the hardcover 1st edition 2003
No part of the material protected by this copyright notice may be reproduced or
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Table of Contents
M. MONIRUL QADER MIRZA, AJAYA DIXIT and AINUN NISHAT
/ Prefaee vii-ix
O. N. DHAR and SHOBHA NANDARGI / Hydrometeorologieal As-
peets ofFloods in India 1-33
M. MONIRUL QADER MIRZA / Three Reeent Extreme Floods in
Bangladesh: A Hydro-Meteorologieal Analysis 35-64
VISHWAS S. KALE / Geomorphie Effeets of Monsoon Floods on
Indian Rivers 65-84
I. M. FAISAL, M. R. KABIR and A. NISHAT / The Disastrous Flood
of 1998 and Long Term Mitigation Strategies for Dhaka City 85-99
HARUN RASID and WOLFGANG HAIDER / Floodplain Residents'
Preferenees for Water Level Management Options in Flood
Control Projeets in Bangladesh 101-129
P. K. MOHAPATRA and R. D. SINGH / Flood Management in India 131-143
RICHARD KATTELMANN / Glaeial Lake Outburst Floods in the
Nepal Himalaya: A Manageable Hazard? 145-154
AJAYA DIXIT / Floods and Vulnerability: Need to Rethink Flood
Management 155-179
Q. K. AHMAD and AHSAN UDDIN AHMED / Regional Coopera-
tion in Flood Management in the Ganges-Brahmaputra-Meghna
Region: Bangladesh Perspeetive 181-198
SUJATA GUPTA, AKRAM JAVED and DIVYA DATT / Eeonomies of
Flood Proteetion in India 199-210
Natural Hazards 28: vii-ix, 2003.
vii
© 2003 Kluwer Academic Publishers.
Preface
South Asia faces flood disaster on a regular basis. This problem crosses interna
tional borders and as the regional hydrology is affected by c1imatic change, the
nature of the problem has become complex. Past approaches focused on altering
of stock and flow of water using embankments and reservoirs, but are insufficient.
The structural solutions are inadequate to address the problems because they re
quire collaboration (such as, regulation andjoint planninglimplementation ofwater
control structures, well maintained sluice gates and embankments) that are difficult
to achieve both within and between countries.
The structural solutions to be effective require major restructuring of both legal
systems and institutions responsible for management. However, little social capa
city exists at present to bring about such transformations in South Asia. In addition,
the prevailing social and political contexts make them difficult to achieve. As a
result, integrated management approaches to flooding advocated by hydrologists
and water resource specialists are inadequate to address the challenges that the
countries of South Asia face.
Given the above limitations on the ability to control water to avoid flood dis
asters, strategies that address emerging challenges will be needed. Flood disaster
has differential impact on individuals, households and communities. People cope
in different ways. Those who have the capacity after being hit by a disaster emerge
faster while those without such capacity sink deeper into the spiral of impover
ishment. Coping strategies inc1ude actions such as migration from flood-affected
areas, flood forecasting, flood insurance of animals and crops, food stockpiling,
providing emergency health services and building flood shelters. They have, how
ever, not been woven systematically into the approach to achieve security from
flooding.
If the approaches build on coping strategies and seek to identify new ones, they
could address the social impacts of flood problems effectively at a lower social,
economic and environmental cost than approaches that attempt to manage or con
trol the resource base itself. Furthermore, responses essential to such strategies
would encourage collaboration among and between countries of South Asia that
will be rooted on the nature on the problem rather than a grand narrative centered
only on specific controllmitigation method.
viii PREFACE
This special issue of Natural Hazards looks at the fiood scene in South Asia
by focusing on both the hazard and the vulnerability aspects including their as
similation. Its conceptual foundations suggest the need for adaptive approaches
to management of risks related to fioods and to identify specific strategies that
could help people overcome the social, economic and environmental vulnerabilities
emerging from fiooding. These issues are addressed by the authors who focus on
hazard and specific fiood events including the social, economic and institutional
processes.
The first article by O. N. Dhar and Shobha Nandargi focuses on hydro
meteorological aspects of fioods in India. The paper suggests that the ground
conditions are quite favourable in generating high run-off because of the antecedent
wet conditions that the monsoon rains create. On the basis of a detailed discussion
of fioods that span fifteen years in different river systems the paper shows that
the problem is confined to the states located in the Indo-Gangetic plains, northeast
India and occasionally in the rivers of Central India.
M. Monirul Qader Mirza analyses three extreme fiood events in Bangladesh.
These were in 1987, 1988 and 1998. These fioods differed in terms of mag
nitude, extent, depth and duration. The external and internal hydro-meteorological
dynamics were also different.
Vishwas S. KaIe analyses the geomorphic effects of monsoon fioods in Indian
rivers. The geomorphic effects of fioods are evident only in certain areas - the
Himalayas, the Thar desert, the Indus and Brahmaputra plains. The peninsular
rivers are, by and large, stable and the geomorphic effects of fioods are modest.
A synthesis of the various case studies available from the Indian region indicates
that often the absolute magnitude of a fiood is not as important with respect to the
geomorphic effects as the fiow stress and competence.
I. M. Faisal, M. R. Kabir and A. Nishat analyse the impact of the 1998 fiood on
Dhaka City. Water entered into the protected part of the city through poorly main
tained infrastructure. Lack of coordination between the agencies responsible for
fiood protection and drainage of the city exacerbated the problem. Non-structural
measures involving retention ponds, maintaining of drains, introducing land zon
ing and fiood proofing in the eastern part of the city can help mitigate fiooding.
Institutional bottlenecks need to be overcome.
Harun Rasid and Wolfgang Haider present fioodplain residents' preference for
fiood water level management options in fiood control projects in Bangladesh. For
this purpose, a maximum difference conjoint (MDC) model was employed as a
part of a questionnaire inside the Compartmentalization Pilot Project (CPP) - Tan
gail. The results of the study indicated that the respondents had a clear preference
for preventing fiooding of their hornes and courty ards and rice fields. They also
expressed a strong concern about malfunctioning of sluices and to a lesser extent
about the changes in the fish habitat.
P. K. Mohapatra and R. D. Singh addresses fiood problems in India, regional
variability of the problem, present status of the ongoing management measures,
PREFACE ix
their effectiveness and future needs in fiood management. Some special problems
related to fioods like dam break fiow, and water logging are also mentioned.
Richard Kattelmann analyses mitigation of at glacial lake hazard in the Hi
malayas. Glacial lake outburst fioods have become an active topic of discussion
within the development community focused on Nepal. The first attempt within
Nepal to reduce hazard of one lake artificially by lowering its water level was
partially completed in June 2000. Beginning work on other hazardous lakes will
require decisions about investment from the international aid community.
Ajaya Dixit provides a holistic picture of fiood disaster in Nepal. The paper
suggests that vulnerability of people in areas prone to fiooding must be addressed
by enhancing their resilience capacity. The approach to fiood mitigation must be
pluralistic and give space to different management styles with varying obligations
at varying scales.
A Bangladeshi perspective on regional cooperation in fiood management in the
Ganges-Brahmaputra-Meghna (GBM) catchments are presented by Q. K. Ahmad
and Ahsan Uddin Ahmed. The existing fiood forecasting and warning capacity
of Bangladesh could be made effective if real-time data could be obtained from
upstream areas of the Ganges, Brahmaputra and Meghna (GBM) catchments. To
that end, Bangladesh needs to foster an effective regional cooperation mechanism
with the other GBM regional countries.
Sujata Gupta, Akram Javed, and Divya Datt present the economics of fiood pro
tection in India. Forty million hectares of land in India is prone to fioods. Though
48% of the vulnerable area has been provided with reasonable protection, fioods
losses continue to increase. This paper presents a simple regression exercise for
three states highly vulnerable to fiood, and argues that fiood protection measures
have been inadequate in controlling los ses and reducing vulnerability.
Collectively, the papers in the volume suggest that diverse causes determine
severity of the events. At the same time, the fiood has differential impact on the
societies hit by fioods.
We would like to thank many individuals in Asia, Europe, Australia and New
Zealand, North and South America who offered their valuable time and expertise,
and through reviewing the manuscripts ensured the high technical standard of this
special issue. We specially extend our thanks to Dr T. S. Murty, Editor (North
America) of Natural Hazards for his outstanding interest on this topic and pion
eering this volume of the Special Issue. We wish to thank Roger Street, Abdel
Maarouf and David Etkin at the Adaptation and Impacts Research Group (AIRG),
Environment Canada and Dr D. K. Barua, Rescan Environmental Services Inc.,
Vancouver for their cooperation.
M. MONIRUL QADER MIRZA
AJAYA DIXIT
AINUN NISHAT
Natural Hazards 28: 1-33,2003.
1
© 2003 Kluwer Academic Publishers.
Hydrometeorological Aspects of Floods in India
O. N. DHAR and SHOBHA NANDARGI
Indian Institute ojTropical Meteorology, Pune -411 008, India
(Received: 27 February 2001; accepted: 18 July 2002)
Abstract. The Indian sub-continent being located in the heart of the summer monsoon belt, receives
in most parts more than 75% of its annual rainfall during the four monsoon months of June to
September. As the bulk of summer monsoon rainfall occurs within aperiod of four months, naturally
majority of floods occur in Indian rivers during this season only. The ground conditions also help in
generating high percentage of run-off because of the antecedent wet conditions caused by rainy speIls
occurring within the monsoon period itself. Besides mentioning different weather systems, which
cause heavy rainfall and consequent floods, a detailed discussion of 15 years' floods in different river
systems has also been given in the article. This study has shown that the flood problem in India is
mosdy confined to the states located in the Indo-Gangetic plains, northeast India and occasionally in
the rivers of Central India.
Key words: Hydrometeorology, floods, cyclonic storms, seasonal monsoon trough, break: monsoon
situations and rainstorm zones
1. Introduction
India being an agricultural country, the prosperity of its agriculture largely depends
upon the rainfall received during its summer monsoon. Considering the beneficial
aspects of summer monsoon rainfall to its agriculture, a British Member of the
then Viceroy's Executive Council said that India's Budget is a gamble on its sum
mer monsoon. It is weH known that summer monsoon rainfall is not uniformly
distributed over the Indian region and there are large variations in its space-time
distribution over different regions. Some parts get heavy to very heavy rainfall
while others get little rainfall. In the long history of about 130 years' (1871-2000)
of rainfall records of this country, it was observed that highest rainfall over the
country was of the order of 22% above the normal annual rainfall of 117 cm in the
year 1961 and it was below normal by about 30% in the year 1877 (Sikka, 2000).
In the remaining years the mean annual rainfall ranged between these two extreme
limits. This unequal distribution of monsoon rainfall is one of the major causes of
floods in the Indian rivers.
Of aH the natural disastrous events, floods by far are the most hazardous, fre
quent and widespread events throughout the world. According to WMO (1994),
on the basis of data of major disasters that occurred around the world during the
period 1963-1992, it has been found that floods cause the maximum damage as
shown below:
2 o. N. DHAR AND SHOBHA NANDARGI
Type of hazard around Damage caused by
the world natural calamities
1. Floods 32%
2. Tropieal cyc10nes 30%
3. Droughts 22%
4. Earthquakes 10%
5. Other disasters 6%
It is also found that maximum number of deaths (i.e., 26%) are caused by
fioods while only 19% are caused by tropieal cyc1ones. Natural calamities like
earthquakes and droughts cause 13% and 3% of deaths respectively (WMO, 1994).
In view of the above, an attempt has been made in this artic1e to give abrief
resume of fioods that have occurred during the 15-year period (1986-2000) of
the summer monsoons. Before that is done, the main hydrometeorological aspects
which cause fioods in the Indian river systems, year after year during the summer
monsoon months are discussed.
2. Mean Summer Monsoon and Annual Rainfall over India
Indian area is of sub-continental size. Its area is about 3,287,263 km2 and it is
located between Long. 68°07' and 97°25' East and Lat. 8°09' and 37°06' North. In
the north, it is bound by the Great Himalayan range whieh runs from east to west
in the form of convex arc whose length is about 2400 km. Its width varies from
about 250 km to about 400 km and it contains some of the highest mountain peaks
of the world like Mt. Everest (8848 m), Mt. Kanchenjunga (8611 m), Dhaulagiri
(8172 m), Annapurna (8078 m), N anga Parbat (8126 m), etc. Figure 1 shows the
broad orographie features of the Indian sub-continent. Some 22 major rivers of the
Indian subcontinent drain the Himalayas from east to west and bring their waters
into the northern plains of India where they join the Ganga and the Indus rivers
of the sub-continent. The source of all their waters in these rivers is contributed
by the melting of glaciers and winter snows of the Himalayas besides the summer
monsoon rainfall.
Long period (1891-1970) average annual rainfall over the contiguous Indian
area is about 117 cm (Dhar et al., 1981 a) which is the highest for a country of
comparable size anywhere in the world. It is however seen that the summer mon
soon rainfall is highly variable both in time and space. Almost 75% of the long
period average annual rainfall comes down in the four monsoon months of June to
September. The heaviest rains of the order of 200--400 cm or even more occur over
northeast India and along the Western Ghats situated along the west coast of the
peninsular India. On the other hand some regions in the extreme western part of the
country, such as western Rajasthan, receive average annual rainfall which is of the
order of about 15 cm or even less. By and large, the annual average rainfall over the
HYDROMETEOROLOGICAL ASPECTS OF FLOODS IN INDIA 3
800 850
I
> 2000 m " .
~
1000-2000 m
c:J 500-1000 m
CJ 0-500 m
"•
SCALE \
sr
Y I I I I KM
Figure 1. Ororaphy of the Indian subcontinent showing regions higher than 500 m, 1000 m,
and 2000 m.
northern Indo-Gangetic plains running parallel to the foot-hills of the Himalayas,
varies from about 150 cm in the east to 50 cm in the west. Over the central parts
of the India and northern half of the peninsular India, it varies from 150 cm in the
eastern half to about 50 cm on the lee side of the Western Ghats. In the southern
half of the Indian peninsula average annual rainfall varies from 100 cm to 75 cm as
we go from east to west. Figure 2 shows the distribution of average annual rainfall
over India.