CS(AR)-29/96-97 : Modelling of an Indian estuary using two dimensional finite element model

Abstract

The basic equations for modeling of any surface water problems are the three dimensional hydrodynamic equations arising from consideration of mass and momentum conservation. In vertically well mixed shallow water bodies, the horizontal components of flow quantities are normally much more significant than vertical components. In such cases, vertically integrated form of the hydrodynamic equation or shallow water equations can be employed efficiently. These are two dimensional dynamic equation of motion and the unsteady continuity equation. Shallow rivers, flood plains, estuaries, harbours, etc. are examples where shallow water equation can be employed.

The study of circulation pattern in estuaries and coastal deltas, where tidal and wind action are predominant is essential for understanding the various processes taking place within the system. A two-dimensional finite element mode, FESWMS-2DH, developed by USGS, is used in this study to simulate the hydrodynamics of Cochin estuary, which lies along Kerala coast.

Calibration have been done using pre-monsoon tide data and the current velocity measured at 11 observation points within the estuary. Model parameters like roughness coefficient and eddy viscosity have been adjusted to simulate the practical scenario. Calibrated model is used to simulate the hydrodynamics of the estuary for pre-monsoon and post-monsoon tides and the results indicates that the model is capable of simulating the hydrodynamics of the estuary.