Author(s): Fábio Paiva Da Silva, Jose Rodolfo Scarati Martins, Fábio Ferreira Nogueira, Lais Ferrer Amorim, Ariel Ali Bento Magalhães

Linked Author(s): Jose Rodolfo Scarati Martins

Keywords: Salinity stratification; Estuarine river; Hydroelectric power plant discharge;

Abstract: Saline stratification is one of the most important physical processes in estuarine areas, which can affect water uses for urban or industrial purposes. It is a complex phenomenon and depends on the estuary geometry, tidal processes, fresh water inputs and human interference on the estuarine environment, such as hydroelectric power plants discharges, water abstractions for human and industrial use, river canalization and so on. The aim of this paper is to present a field survey on saline stratification in Cubatão River, in Brazil, and investigate its relationship with the natural fresh water and Henry Borden Hydroelectric Power Plant water’s discharge. Cubatão River has an estuarine reach located at Santos estuarine system in São Paulo, Brazil and it is an indispensable source of water resources for urban and industrial supply. Fieldwork was conducted for approximately four months, from 03 November 2016 to 04 March 2017 and the monitoring parameters were salinity concentration, water level, precipitation and Henry Borden Discharge. Salinity concentration was measured in three different depths in the water column in order to examine the stratification patterns. Salinity stratification presented a complex behavior due to the effects of Henry Borden Hydroelectric Power Plant discharge, precipitation and tidal activity. During dry periods and reduced Henry Borden discharges, salinity concentration becomes high and saline stratification is distinguishable in the water column; while during higher Henry Borden discharges combined with high precipitation events, salinity concentration decreases significantly, indicating that seawater is flushed out Cubatão River. The most important finding of this monitoring period is that the salinity stratification pattern in Cubatão River varies considerably under different forcing events. Freshwater flow is the primary environmental factor controlling the stratification pattern in Cubatão River, but it is also strongly affect by hydroelectric power plant discharge and rainfall events. Salinity stratification investigation provided a framework for characterizing and understanding spatial patterns in estuaries and their variability over time. The field survey provided a unique observation of the hydroelectric power plant discharge effects on saline stratification in an estuarine river and the results are valuable for further water uses in Cubatão River particularly.

DOI: https://doi.org/10.3850/38WC092019-1304

Year: 2019