Estuarine turbidity maximum in six tropical minor rivers, central west coast of India

Abstract

Understanding patterns of erosion and sedimentation and their driving mechanisms is important for formulating a variety of estuarine management issues (conservation, shoreline protection, navigation, dredging and embanking). Therefore, the present study aims to determine the factors influencing the seasonal distribution and dynamics of suspended particulate matter (SPM) of two meso-(Mandovi and Zuari) and four micro-tidal (Terekhol, Chapora, Sal, and Talpona) river estuaries of Goa, on the central west coast of India. These estuaries exhibited salinity stratification near their mouths during the wet season and well-mixed water columns during the dry season. The SPM concentrations were two times higher in the wet season than in the dry season. Estuarine turbidity maximum (ETM) was a consistent feature in both the seasons at the mouth of the estuaries, except in the estuary of the Sal River. The in situ vertical distribution of SPM volume concentration and mean particle size allowed for a better visualization of the ETM formation and distribution. The gravitational circulation as well as flocculation at the salt–freshwater interface during the wet season and the impact of tidal and wind-induced currents at the river mouths during the dry season were primarily responsible for the formation of the ETMs.