Circulation and mixing process in Vasishta-Godavari estuary, east coast of India

• Main Authors: Kumar, A.R.S, Murty, T.V.R, Rao, M.M.M, Rao, V.R, Reddy, B.S.R
• Format: Journal Article
• Language: English
• Published: Andhra University 2005

Circulation and Mixing Process in Vasishta-Godavari Estuary, have been studied by using estuarine classification model. Analysis of salinity, salt budget, diffusion coefficients and flushing times based on salinity data of Vasishta-Godavari estuary for different months has been carried out. I-D advection-diffusion model has been adopted for computing diffusion coefficients along the channel axis using input data on tidal average salinity, bathymetry and river discharge. The mean value of diffusion coefficient ranges between 20880 m sup(2)/s - 3888 m sup(2)/s in the southwest monsoon season (July-September) while for post and pre-monsoon seasons (November-May) the coefficient is between 515 m sup(2)/s and zero. The fluctuations in diffusion coefficients reflect the topographic features. The maximum value of flushing time for Vasishta-Godavari is 75.17 tidal cycles during the period of low discharge, while minimum is 0.81 during high river discharge. With the onset of southwest monsoon, the runoff increases considerably and the estuary loses about 90% of salt content during the first 2 months of the season. About 75% of this loss is recovered in the subsequent 3 months when the runoff decreases. The estuarine salt budget shows an increase in salt content gradually from September to January. Model studies based on these observations may be more useful in understanding the basic mechanisms involved in circulation, mixing and flushing aspects of the estuary