Application of 2D Mathematical Model for Verification of Water Velocity at Coastal Area of Bangladesh

Abstract

The coastal areas of Bangladesh are different from the rest of the country due to its unique geo-physical characteristics and vulnerability to several natural disasters like cyclones with associated storm surges, erosion and accretion. Natural hazards are increasing with high frequency and intensity along the coast of Bangladesh with the changes of global climate. These extreme natural events are termed disasters when they adversely affect the whole environment including the human beings, their shelters or the resources essential for their livelihoods. Water movement in the coastal zone of Bangladesh is determined by the influences of fresh water flow from the rivers, tide coming from the Bay of Bengal, and meteorological conditions (low pressure systems, wind, storms and cyclones). A mathematical model study has been carried out to simulate the tidal flow velocity in the near shore coastline of Bangladesh. In this study a two dimensional hydrodynamic model DIVAST (Depth Integrated Velocity and Solute Transport) has been used considering the different parameters like co-efficient of eddy viscosity, Manning roughness, advective and diffusion co-efficient etc. of the Bay of Bengal. The DIVAST model is based on FORTRAN PROGRAMING and it has a number of modules for different purposes with different sets of equations. In this study hydrodynamic module has been used. 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 water elevation η with respect to mean sea level and the respective velocity components U, V in the x and y directions are calculated across the selected coastal domain for a prescribed set of initial and boundary conditions. Simulated velocity has been verified at selected locations of coastal area with the measured field data and compared with the other study carried out in the coastal region of Bangladesh. Viewing over the DIVAST simulated results very good agreement is found between the measured data as well as to the other study. This encouraging good result justifies that the DIVAST model works reasonably well for the selected domain of the Bay of Bengal.