Stratification and salinity distribution in Cochin estuary, southwest coast of India

Abstract

Stratification and distribution of salinity in relation to tides and freshwater discharges have studied during May, July, November 1985 and January 1986. The extent of intrusion of saline water depends on the strength of the tidal influx and the freshwater efflux which varies with season. May (premonsoon) exhibits least stratification with highest salinity (34.6 x 10 ^-3) at the bottom. Sudden changes are brought in the environment with the onset of the monsoons. During July (SW monsoon) as saline wedgae is present and the surface waters show nearly freshwater conditions. Salinity shows increase during November (NE monsoon) and January (winter) due to reduced monsoonal influence. Diurnal variations in salinity are in phase with the tides exhibiting increase during flood tide and decrease during ebb tide. Considerable mixing of water takes place at the final stages of flood tides and the mixed water flows out during ebb tides.