The study deals with flow computation in Saptamukhi river estuary in Sunderbans delta of West Bengal using finite element method. Complex interactions between physical, chemical and biological processes are present in coastal areas. Water circulation is one of the most important factors controlling these processes. The study of the real hydrodynamic regime and proper management of estuaries, lagoons and coastal regions due to high tides, peak flows erosion, sedimentation and pollutant load discharges is vital.

Many problems of hydraulic engineering require information concerning water heights and currents in the two dimensional horizontal domain, typical cases being bays, estuaries, harbours and wide rivers. Recent advances in computation technology allow us to use sophisticated numerical methods for the analysis of such problems. Lately, mathematical modeling has become a useful tool in the field of hydraulic engineering.

In the beginning, modeling was carried out by finite difference methods. However, the complex topography and irregular boundaries of two-dimensional cases require better and more reliable techniques such as finite element technique to obtain detailed information. In recent years, it has been used to develop two-dimensional models for the simulation of bays, estuaries, harbours and lakes.

More specifically, the present study attempts to (i) compute the effect of tides (neap tides and spring tides) (ii) effect of different flow conditions (normal and peak flow conditions) and (ii) sensitivity of model parameters. The results obtained have been compared with the observed flow data of the river estuary.

A hydrodynamic two-dimensional model (FESWMS-2DH) has been used to compute the two dimensional flow velocity and water surface profiles due to interaction of high tide and peak flow from the Saptmukhi river estuary (east and west gullies) and Storag Lacam’s channel of the Sunderbans Delta of West Bengal.

In the western area of the estuary, there is inadequate security against tides and waves resulting in occasional damage of crops, loss of life and property, difficulties in maintaining the huge length of embankments, lack of proper drainage facilities and insufficient freshwater resources.

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