Some aspects of the hydrographical conditions of the backwaters around Willingdon Island (Cochin)

摘要

The Cochin backwaters which form more or less a northward extension ofudthe Vembanad lake have all the characteristics of a typical estuary. On the southernudside of the backwaters there is the influx of waters of the Pampa river and on theudnorthern side, the Periyar. The channel to the west opening out into the ArabianudSea is the main area for the exchange between the sea and the estuary. These backwatersudthus form a very interesting subject of study not only from the point of view ofudthe seasonal variation in the various hydrographic parameters, but also this is anudarea where there is considerable scope for a theoretical study of magnitude of exchangesudacross the transition. The tidal exchanges across the channel are fairlyudhigh, as also the influx of freshwater. Apart from the influence of monsoon rainsudand the considerable amount of evaporation during hot months in this shallow environment,udthe influence of various types of phenomena in the Arabian Sea such asudupwelling, sinking, coastal piling etc. is quite considerable and these result in certainudcharacteristic variations in the hydrographical and associated conditions in this area.udThe present paper is an attempt to work out the main pattern of distribution of theudvarious parameters—spatial as well as temporal and to indicate the mixing processesudwhich make this area quite interesting not only to the hydrographer but to the biologistudas well.