Have coastal embankments reduced flooding in Bangladesh?

Adnan, Mohammed Sarfaraz Gani and Haque, Anisul and Hall, Jim W. (2019) Have coastal embankments reduced flooding in Bangladesh? Science of the Total Environment, 682. pp. 405-416. ISSN 1879-1026 (https://doi.org/10.1016/j.scitotenv.2019.05.048)

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Abstract

From the 1960s, embankments have been constructed in south western coastal region of Bangladesh to provide protection against flooding, but the success of the polder programme is disputed. We present analysis of floods during the years 1988–2012, diagnosing whether the floods were attributable to monsoonal precipitation (pluvial flooding), high upstream river discharge into the tidal delta (fluvio-tidal flooding), or cyclone-induced storm surges. We find that pluvial flooding was the most frequent, but typically resulted in less flooded area (11.44% of the region on average)compared with the other forms of flooding. The greatest area of inundation (48% of total area)occurring in 2001 as a consequence of fluvio-tidal and surge flooding, whilst cyclone Sidr in 2007 flooded 35% of the area. We modelled these different forms of inundation to estimate what flooding might have been had the polders not been constructed. For the ‘no embankment’ counter-factual scenario, our model demonstrated that because of a combination of subsidence and inadequate drainage, construction of the polders has increased the pluvial flooded area by 6.5% on average (334 km2). However, during the 1998 fluvio-tidal flood, the embankments protected an estimated 54% of the area from flooding. During the cyclone Sidr storm surge event, embankment failure in several polders and pluvial inundation resulted in 35% area inundation, otherwise, the total inundation would have been 18% area. We conclude that whilst polders have provided protection against storm surges and fluvio-tidal events of moderate severity, they have exacerbated more frequent pluvial flooding and promoted potential flooding impacts during the most extreme storm surges.

ORCID iDs

Adnan, Mohammed Sarfaraz Gani ORCID logoORCID: https://orcid.org/0000-0002-7276-1891, Haque, Anisul and Hall, Jim W.;
  • Item type:Article
    ID code:85105
    Dates:
    Date
    Event
    10 September 2019
    Published
    5 May 2019
    Published Online
    4 May 2019
    Accepted
    Notes:Funding Information: This work is an output from the REACH programme (www.reachwater.org.uk)funded by UK Aid from the UK Department for International Development (DFID)for the benefit of developing countries (Aries Code 201880). However, the views expressed, and information contained in it are not necessarily those of or endorsed by DFID, which can accept no responsibility for such views or information or for any reliance placed on them. We thank the anonymous reviewers for their careful reading of our manuscript and insightful comments and suggestions. Funding Information: This work is an output from the REACH programme ( www.reachwater.org.uk ) funded by UK Aid from the UK Department for International Development (DFID) for the benefit of developing countries (Aries Code 201880). However, the views expressed, and information contained in it are not necessarily those of or endorsed by DFID, which can accept no responsibility for such views or information or for any reliance placed on them. We thank the anonymous reviewers for their careful reading of our manuscript and insightful comments and suggestions. Publisher Copyright: © 2019 Elsevier B.V. Mohammed Sarfaraz Gani Adnan, Anisul Haque, Jim W. Hall, Have coastal embankments reduced flooding in Bangladesh?, Science of The Total Environment, Volume 682, 2019, Pages 405-416, https://doi.org/10.1016/j.scitotenv.2019.05.048
    Subjects:Technology > Engineering (General). Civil engineering (General)
    Department:Faculty of Engineering > Civil and Environmental Engineering
    Depositing user: Pure Administrator
    Date deposited:13 Apr 2023 08:25
    Last modified:11 Nov 2024 13:54
    Related URLs:
    URI:https://strathprints.strath.ac.uk/id/eprint/85105
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