Revista Sociedade & Natureza (Dec 2006)
ANÁLISE UNIDIMENSIONAL DOS PROCESSOS DE MISTURA NO SISTEMA ESTUARINO DO RIO PERIÁ (MA), BRASIL / One-dimension analysis of mixing processes of the Periá River Estuary (MA), Brazil
Abstract
The objective of present work is to analyze the processes of mixture in the estuarinesystem of the Periá River (MA) and to classify the system into zones following Kjerfve (1987). The mathematical model of Dyer and Taylor (1973) was used in order toanalyze the mixture processes. To attain the objectives, the bathymetry of the estuarinesystem was obtained, allowing to define the limits of high and low tides. The one-dimension analysis considered: salinity and the water concentration and/or fresh waterfraction, in high and low tides; the rates and times of discharges; and the volumes offresh water restrained in the estuary in high and low water slacks. The followingresults were obtained: the water volume in the system has maximum of 64,96 * 106 m3and minimum of 0,12 * 106 m3; the tidal prism has maximum of 7,1 * 106 m3 andminimum of 0,045 * 106 m3; the fresh water concentration was higher in low tide (0,99* 106 m3 ) than in high tide (0,91 * 106 m3 ); the salt concentration was always larger inhigh than in low tides, having maximum of 34 ups and minimum of 0,34 ups; regardingthe water volume restrained in the low and high water slacks, it was larger in theebbing (5,36* 106 m3) than flooding (1,12 * 106 m3); and finally, the discharge timespresented larger values in high tides (2 tidal periods) and smaller in low tides (1.2tidal periods).The study allows to conclude that the salinity and fresh water dischargein the estuarine system of Periá River are the dominant factors in the processes ofmixture.
