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Propagation of tides in the Mandovi and Zuari estuaries

DRS at CSIR-National Institute of Oceanography

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Title Propagation of tides in the Mandovi and Zuari estuaries
 
Creator Shetye, S.R.
 
Subject estuaries
tidal propagation
stream flow
runoff
tidal amplitude
mathematical models
conservation of momentum
equation of continuity
 
Description The Mandovi and the Zuari are two shallow estuaries that are located in Goa and join the Arabian Sea. The main channel of each is about 50 km long, has its cross-sectional area decreasing rapidly in the upstream direction, and receives large amounts of riverine freshwater during the southwest monsoon and little during the rest of the year. Tides in the channels exhibit the following characteristics: (a) The speed of propagation is about 6.5 ms sup(-1); (b) tidal amplitude remains unchanged over a distance of about 40 km from the mouth; (c) mean water level near the head increases with increase in runoff; (d) tidal amplitude decays rapidly over approx equal to 10 km near the head, the decay is more rapid during periods of higher runoff. A nonlinear numerical model based on the equations for conservation of momentum and mass reproduces all the observed features. The model fields show that momentum balance in the channels is primarily between pressure gradient and friction. Assuming such a balance, a linear analytic model for tidal propagation in a channel whose cross-sectional area decreases exponentially with distance from the mouth and has influx of riverine freshwater at its head is formulated. The model solution mimics the observed features (a)-(c) cited above but not (d). Our conjecture is that the quadratic friction term in the momentum balance and the nonlinear term in the continuity dequation are essential to simulate the decay of tidal amplitude at the upstream end.
 
Date 2009-01-10T11:33:46Z
2009-01-10T11:33:46Z
1999
 
Type Journal Article
 
Identifier Sadhana, Vol.24; 5-16p.
http://drs.nio.org/drs/handle/2264/1815
 
Language en
 
Rights Copyright [1999]. All efforts have been made to respect the copyright to the best of our knowledge. Inadvertent omissions, if brought to our notice, stand for correction and withdrawal of document from this repository.
 
Publisher Indian Academy of Sciences, Bangalore, India