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INTRODUCTION
The Cochin coast is one of the coastal zones with high anthropogenic influence, owing to the extensive backwater system draining into the ocean. Various aspects like hydrodynamics, chemical constituents, biological population, and sediment characteristics of the Cochin backwaters were investigated by numerous researchers. (Gireeshkumar, Deepulal, and Chandramohanakumar, 2013; Hatha, Chandran, and Rahiman, 2004; Lakshmanan et al., 1987; Menon, Balchand, and Menon, 2000; Shivaprasad et al., 2013; Srinivas et al., 2003). However unlike the backwaters the Cochin shelf waters were not given much attention, although it was evident that the coastal water of the Cochin is significantly influenced by the influx from the backwaters. The dispersion of the land based inputs in the coastal waters is controlled primarily by the hydrodynamics of the shelf water. Therefore a detailed analysis of the near shore hydrodynamic is essential for understanding the fate of materials entering the coastal waters through the estuary.
Often an in situ field measurement provides point to point data which prove to be inadequate in understanding the synoptic variability in circulation, mixing and stratification characteristics. Therefore modelling serves as an indispensable tool in determining the temporal and spatial variability. The present study attempts to model the near shore hydrodynamics as a precursor to the ecosystem modelling of the Kochi shelf waters. Modelling of various hydrographical parameters such as flow field, temperature, salinity, etc., is the core of inferring the nutrient dynamics besides determining the dispersion of land derived materials in coastal water.
In this paper, a 3D modelling approach is adopted to better understand the flow field and consequent variability of temperature and salinity over the vertical column. Unlike 2D models, 3D models are capable of capturing the phenomenon like coastal upwelling and downwelling, pertaining to the vertical column. The present 3D modelling study needs to be considered as a pilot study to understand the capabilities and limitations of a 3D model when implemented for a small regional scale study.
BACKGROUND
The hydrography and the circulation characteristics of the west coast of India, especially the Cochin coast can be found in the works of Muraleedharan and Prasanna Kumar (1996); Prasanna Kumar et al. (2005); Shenoi et al. (2005); Shetye et al. (1990); Shetye, Gouveia, and Shenoi (1994) and so on....