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Nat Hazards (2017) 86:669694
DOI 10.1007/s11069-016-2711-4
ORIGINAL PAPER
Mohammad Asad Hussain1 Yoshimitsu Tajima2
Received: 4 April 2016 / Accepted: 28 November 2016 / Published online: 7 December 2016 Springer Science+Business Media Dordrecht 2016
Abstract The tidal amplitude at the Bay of Bengal along the Bangladesh coast varies from 2 to 7 m, whereas the tidal phase differs by more than 3 h from the outer part toward the inner part of the Meghna Estuary. At the time of cyclone landfall, the tidal phase has a signicant impact on surge height, arrival time and duration. In this paper, the nature of surgetide interactions at the Bay of Bengal along the Bangladesh coast has been investigated using a two-dimensional nonlinear shallow water model coupled with a storm surge model. Two previous major storm surge events along the Bangladesh coast have been analyzed for surgetide interaction: Cyclone 1991 and Cyclone Sidr in 2007. To investigate the impact of the tidal phase on surge characteristics, in addition to the base cases, storm surges have been calculated at different phases of an entire tidal cycle at 1-h intervals. The results indicate that during the ebb tides the calculated total surge height of the surgetide interaction model was higher compared to the total surge height obtained by superimposing surge height that is separately calculated with mean water level over the local tidal water level; the opposite occurs during high tide. The surge propagation time toward the inner part of the bay signicantly varied depending on the tidal phases. When the tidal water level along the coast was low, the speed of surge propagation was much slower compared with when the tidal water level was high. The surge duration increases when the falling surge prole encounters an opposing strong tidal current at the landfall location.
Keywords Storm surge modeling Bay of Bengal Nonlinear surgetide interaction
Surge characteristics
& Mohammad Asad Hussain [email protected]
1 Institute of Water and Flood Management, Bangladesh University of Engineering and Technology,
Dhaka 1000, Bangladesh
2 Department of Civil Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo ku, Tokyo 113-8656, Japan
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