Seasonal Flood Forecasts and Warning Response Opportunities: ENSO Applications in Bangladesh

225 Pages·2022·14.157 MB·English

by  Md. Rashed Chowdhury

Disaster Risk Reduction
Methods, Approaches and Practices
Md. Rashed Chowdhury
Seasonal Flood
Forecasts
and Warning
Response
Opportunities
ENSO Applications in Bangladesh
Disaster Risk Reduction
Methods, Approaches and Practices
Series Editor
Rajib Shaw, Keio University, Shonan Fujisawa Campus, Fujisawa, Japan
Disaster risk reduction is a process that leads to the safety of communities and
nations. After the 2005 World Conference on Disaster Reduction, held in Kobe,
Japan, the Hyogo Framework for Action (HFA) was adopted as a framework for risk
reduction. The academic research and higher education in disaster risk reduction
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practitioners to analyze field practices and link them to theory and policies with
logic, data, and evidence. In this way, the series will emphasize evidence-based risk
reduction methods, approaches, and practices.
Md. Rashed Chowdhury
Seasonal Flood Forecasts and
Warning Response
Opportunities
ENSO Applications in Bangladesh
Md. Rashed Chowdhury
Laveen, AZ, USA
ISSN 2196-4106 ISSN 2196-4114 (electronic)
Disaster Risk Reduction
ISBN 978-3-031-17823-8 ISBN 978-3-031-17825-2 (eBook)
https://doi.org/10.1007/978-3-031-17825-2
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This book is dedicated to the memory of my
late father
Dr. A K M Rafiquzzaman Chowdhury
Preface: Why Are El Niño-Southern Oscillation
(ENSO)-Based Seasonal Forecasts Important in
Bangladesh?
Until now, flood hazard in Bangladesh was considered mainly from the perspective
of losses and damage to property. Believing in the ability of technology to control
the environment or landscape, national planners and decision-makers advocated
large-scale engineering solutions (or structural measures) as a buffer against this
particular kind of hazard. While accepting the view that solutions to flooding haz-
ards hinge both on structural and non-structural measures, this book focuses on the
formulation of non-structural solutions along with regulatory lines. Specifically, it
aims to provide a brainstorming discussion on the science of the El Niño-Southern
Oscillation (ENSO) and its correlation to local climate data in Bangladesh. While
the monsoon subsystems in the western Pacific are connected to variations in sea
surface temperatures (SSTs) in the Pacific, research specifically addressing the
ENSO climate cycle and climate variation in Bangladesh is scarce. Therefore, the
primary intention of this book is to develop a diagnostic outlook on ENSO-based
seasonal flood forecasts for Bangladesh by using teleconnections with tropical SSTs
and surface wind anomalies. This book aims to provide insight into the role of inter-
annual climate variability information for capacity-building efforts in Bangladesh.
Based on 20 years of research and working experience in Bangladesh, and other
small island countries in the Pacific, the author found that the ENSO-based seasonal
forecasts would provide enhanced applications for seasonal flood forecasting in
Bangladesh. Bangladesh can, therefore, benefit by developing potential prediction
schemes utilizing ENSO and local climate data.
This research started after the catastrophic flooding event of 1998 when the
author was working in the Flood Forecasting and Warning Center (FFWC) of the
Bangladesh Water Development Board (BWDB). Currently, the flood of 1998 is
considered to be the most catastrophic flood in Bangladesh’s history. For this rea-
son, many of the research findings reported here are based on the 1950–1998 data.
However, new analyses with more recent data (up to 2020) have been conducted,
which produced promising results from an adaptation planning perspective.
Laveen, AZ, USA Md Rashed Chowdhury
vii
Acknowledgments
This work originally started in 2001 and was supported by the postdoctoral program
at the International Research Institute for Climate and Society (IRI) (https://iri.
columbia.edu/) (Earth Institute of Columbia University), administered by the
University Corporation for Atmospheric Research (UCAR). I am particularly thank-
ful to Dr. Neil Ward for supervising my work during the entire period of this
research. Grateful acknowledgments are also extended to Drs. Reid Basher, Upmanu
Lall, Tony Barnston, and Carolyn Mutter for their comments. A very special thanks
to Dr. Ousmane Ndiaye for his outstanding support on GrADS and other IRI-data
uses. I also gratefully acknowledge the IRI for providing easy access to data.
I would like to express my gratitude to the Flood Forecasting and Warning Center
(http://www.ffwc.gov.bd/) of the Bangladesh Water Development Board (BWDB)
(warmest regards to Engr. Sharif Rafiqul Islam, who later became the Director
General of the BWDB), Climate Diagnostics Center (CDC; https://psl.noaa.gov/
data/correlation/), and the University of Hawaii Sea Level Center (https://uhslc.
soest.hawaii.edu/) for providing easy access, manipulation, and visualization of dif-
ferent types of earth, ocean, and science data. Thanks are also due to the Pacific
ENSO Applications Climate (PEAC) Center for providing a very congenial atmo-
sphere for research pursuit. A very special thanks to Dr. Tom Schroder and Professor
P.S. Chu for providing me with necessary research support and guidance. While
writing this book, I also had to rely on the research done for my PhD dissertation. I,
therefore, owe a lot to the University of Tsukuba (and Monbukagakusho/Japanese
Government Scholarships) and would like to express my profound gratitude to my
PhD supervisor Dr. Yohei Sato (and students of Sato Lab), and the other faculty
members of the Policy and Planning Sciences of Tsukuba University.
While working at the PEAC Center, field visits to different US-Affiliated Pacific
Islands (USAPIs) enriched my El Niño-Southern Oscillation (ENSO)-knowledge
base, and I am particularly thankful to the Weather Service Officials (WSOs) of
those islands for sharing their knowledge and a big Mahalo for giving me a rousing
welcome. I also appreciate Mr. Charles “Chip” Guard (Weather Forecast Office,
Guam) for being a good friend and a mentor.
ix
x Acknowledgments
Finally, many thanks to all of my family members including my mother, wife,
sons (Annay and Anan), daughter (Ohana), brothers, and sisters for their encourag-
ing words at different phases of my work and life.
Last but not least, a special thanks to Springer publication for publishing this
book and a very special thanks to Ms. May Izumi for proof editing and providing
many important comments on the preparation of this manuscript.
Md Rashed Chowdhury
Contents
1 Introduction: Seasonal Flood Potential in Bangladesh . . . . . . . . . . . . 1
1.1 The Importance of Seasonal Flood Forecasts in Bangladesh . . . . . 1
1.2 What Is a Probabilistic Seasonal Forecast? . . . . . . . . . . . . . . . . . . . 2
1.3 What Is ENSO? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.4 La Niña and Bangladesh Floods? . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.5 What Is the Causal Connection Between La Niña and Seasonal
Flooding in Bangladesh? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.6 How Helpful Are the Seasonal Forecasts in Bangladesh? . . . . . . . . 4
1.7 Literature Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.8 Book Contents: Chapters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Hydro-Meteorological Variability and Opportunity
for Seasonal Forecasts in Bangladesh . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Introduction: Flood Hydrology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.1 Rainfall Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1.2 Flood Hydrology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.1.3 Sources of Floods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1.4 Causes of Floods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1.5 Occurrence of Floods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.1.6 Flood Frequency Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.2 Hydro-Meteorological Variability:
Ganges- Brahmaputra-Meghna Basins . . . . . . . . . . . . . . . . . . . . . . . 15
2.2.1 Data, Basic Indices, and Method . . . . . . . . . . . . . . . . . . . . . 17
2.2.2 Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.3 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Appendices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Appendix 1: Result of the Frequency Analysis
of Flood-Affected Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Appendix 2: Gumbel’s Extreme Value Distribution . . . . . . . . . . . . . . 27
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
xi