A preliminary enquiry on the hydrological and planktological conditions in the river mouth region was conducted during the period 1950-52 and the results published in an abstract form (George, 1953a). This study was later extended to cover the 25 km seaward region of the estuary in 1954. As is well known, the Malabar coast is highly productive from the fisheries point of view and it was also observed that the sea waters of the inshore region off Calicut are rich in plankton and nutrient salts (George, 19536). Results of the present investigation would therefore serve to assess the influence of land drainage in the enrichment and replenishment of the coastal waters and allied factors. The west coast of India which is subjected to a heavy rainfall amounting to more than 300 cm per annum, is characterised by numerous short and swift rivers which carry the,enormous amounts of the waters from the Western Ghats into the sea. 

Hydrology, seasonal variations, Korapuzha estuary, Kerala