Spatial and temporal distribution of total suspended matter and other associated parameters in the Zuari estuary, Goa

Abstract

The total suspended matter (TSM) during the fair weather season increases from the mouth to about one third of the length (Cortalim) of the Zuari estuary and then it decreases towards upstream. Although the TSM content increases remarkably with the onset of the monsoon at its peak the amount of TSM decreases considerably reaching a minimum in September. The zone of high TSM concentration (about 5 km length) occurs during the fair weather season towards the downstream side of Cortalim, and then it disappears gradually during the monsoon. At any given place in the Zuari estuary the TSM value is always higher in the near bottom waters than in the near surface waters. Salinity decreases from the mouth towards upstream. The pH and salinity share a direct relationship in the tidal reaches of the estuary and the temperature of the water is influenced by the atmospheric temperature. The overall distribution of TSM and other parameters reflect the conditions associated with moderately high flood currents within the estuary. The study also reveals that the estuary assumes a partly mixed state during the monsoons and returns to completely mixed nature during the fair weather season.