Assessment of nearshore hydrodynamic process along the coast of Cox's Bazar

Abstract

The coastal area of Bangladesh is different from the rest of the country due to its unique geo-physical characteristics and vulnerability due to several natural disasters like erosion, cyclone, storm surges, tsunami, sea level rise, settlement and also various forms of pollution. These natural hazards are increasing with high frequency and intensity along the coast of Bangladesh and adversely affected lives and livelihoods in the coastal zone and slowed down the pace of social and economic developments in this region. Water movement in the coastal zone of Bangladesh is determined by the wave coming from the Bay of Bengal and other meteorological conditions. A mathematical model study has been carried out to simulate the maximum wave height in the nearshore coastline of the Cox's Bazar area in Bangladesh. In this study a two dimensional hydrodynamic model DIVAST (Depth Integrated Velocity and Solute Transport) has been established based on different parameters like co-efficient of eddy viscosity, Manning roughness coefficient, advective and diffusion co-efficient etc. The DIVAST model is based on FORTRAN PROGRAMING and it has a number of modules for different purposes with different sets of equations. The hydrodynamics of the selected area of the Bay of Bengal has been simulated by solving two-dimensional depth integrated momentum and continuity equations numerically with finite difference method. Consequently the respective velocity components in the x and y directions has been calculated across the selected coastal domain for real set of initial and boundary conditions. The hydrodynamic model has been set up at neareshore coastal water of Cox’s Bazar in Bay of Bengal. The model output consists of wave height, wave direction, celerity, group velocity and water velocity at different grid point in the study area of Bay of Bengal. In this study, velocity profile has been observed and simulated for different wave angle from offshore area and also the neareshore wave climate has been developed. Simulated maximum wave height is verified at selected locations of coastal area with the measured field data, that is the maximum wave height along the coastal zone of Cox’s Bazar coastline in Bangladesh. The output from the mathematical model DIVAST shown very good agreement with the measured data. These simulated results can be used for nearshore wave climate around the area. As a conclusion it can be said that the DIVAST model simulate reasonably sound output data for the selected domain of the nearshore zone of the Cox’s Bazar area in Bangladesh.