| Author | Khan, Mohammad Arif Badsha |
| Call Number | AIT Thesis no. WM-00-09 |
| Subject(s) | Saltwater encroachment--Bangladesh--Lower Meghna estuary
|
| Note | A thesis submitted in partial fulfillment of the requirements of the degree of Master of
Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Abstract | In the present study, Interaction of tide and river flows in Lower Meghna is investigated
using the method of harmonic analysis and analytical solutions. As the records of water
level along the river are contributed by various constituents of tide so harmonic analysis
has been applied to decompose the complicated interaction of the fresh water discharge
with various constituents of tides into its individual interaction with each constituent.
Four main constituents are included in this study. Results of water level obtained by
applying the analytical model to stations along the Lower Meghna are compared very
well with the observed values.
In analytical model, the governing equations are solved using the approximation method
of perturbation to investigate the interaction of tide and fresh water discharge of lower
Meghna river of which the cross-section and width varies exponentially. The zeroth order
solution is obtained by direct integration and the IPPEN's solution is adopted for the first
order solution. The relationship of important dimensionless parameters of the tide with
fresh water discharge, especially the dimensionless damping modulus, has been
established.
These informations are required to calculate the salinity intrusion in estuaiy. Profiles of
maximum and mean salinity as well as the intrusion length along the Lower Meghna river
has been investigated. The Lower Meghna River shows a period of low flow in AprilMay. During this period saline water from the sea, under the actions of tide and diffusion,
intrudes into the lower reach of the river, causing salinity pollution. Tidal convection of
salinity profile has been studied. Flow conditions at different stations during periods of
low flow has been investigated. Similar to the interaction of tide and river flow, analytical
solutions have been described in decomposing the steady state component of salinity
from the unsteady component of tidal convection of salinity. Comparison between
computed and observed average salinity along the length from downstream boundary has
been found. |
| Year | 2001 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Engineering and Management (WM) |
| Chairperson(s) | Suphat Vongvisessomjai |
| Examination Committee(s) | Mark, Ole ; Izumi, Norihiro ; Sutat Weesakul ;Iida, T.
|
| Scholarship Donor(s) | Danida.
|
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2001 |