Abstract:
The coastal region of Bangladesh is comprised of morphologically dynamic river
network, sandy beaches and estuarine system. The interaction of huge fresh water
and sediment load coming from the upstream river system and saline waterfront
penetrating inland from the sea are the key factors for a vulnerable coastline. Meghna
Estuary is located at the central part of the coastline of Bangladesh. The tidal
behaviour, upland discharges and wind fields vary distinctly in the coastal areas of
Bangladesh. The tides in the coastal and estuarine areas of Bangladesh are semidiurnal
in nature. Determination of tidal level for understanding the hydraulic
behaviour of the coastal region is very important and crucial for taking any decision
of coastal area development.
A two dimensional hydrodynamic Depth Integrated Velocity and Solute Transport
(DIVAST) model based on FORTRAN program has been set up for Bay of Bengal
for simulation of tidal levels. The bathymetry of the Bay of Bengal has been
generated with the numerical model DIVAST based on the data of Meghna Estuary
Study (MES) phase I and phase II. The simulated tidal levels of the Bay of Bengal
model have been calibrated and verified with the observed tidal levels of tidal gauge
stations located at Daulatkhan, Tazumuddin, Hatiya, Sandwip, Feni River, Rangadia
and Hiron Point locations. The calibration and verification time periods have been
considered for spring tidal conditions at dry season from 12 January 2008 to 14
January 2008 and monsoon season from 31 May 2009 to 02 June 2009 respectively.
Time of simulation of the model is set for continuous five tidal cycles of 62 hours
duration and a total of 40 points of tidal levels are generated.
The DIVAST model simulated mean high spring tidal levels in the verification
results have been found 1.73 m MSL at Daulatkhan, 1.93 m MSL at Tazumuddin,
4.6 m MSL at Hatiya, 5 m MSL at Sandwip, 4.1 m MSL at at Feni River, 5.4 m MSL
at Rangadia and 2.1 m MSL at Hiron Point. The simulated tidal ranges have been
observed as micro-tidal at Daulatkhan, meso-tidal at Tazumuddin and Hiron Point,
macro-tidal at Hatiya, Sandwip, Feni River and Rangadia. The simulated tidal levels
have also been compared with the simulated tidal levels of two other studies and
results have been found in good agreement.
