Regionalização das vazões ecológicas em eventos extremos de seca influenciados pelo ENSO (EL-Niño Southern Oscillation) e seu comportamento face à dinâmica estuarina: Maranhão - Brasil

Abstract

This study addresses the influences of the Niño Oceanic Index variation on minimum flows in periods of extreme drought in the state of Maranhão, based on the El-Niño Southern Oscillation (ENSO) anomaly, and explores the different scenarios of the current freshwater flow of Complexo Estuarino de São Marcos (CESM). Analysis of data from Agência Nacional de Águas (ANA) showed that, for the Mearim River - with the greatest contribution to the São Marcos estuary - there is an reference flow Q7.10 of 30.36m3/s based on the automatic station closest to the mouth. Data from automatic collection station databases are also compared with Acoustic Doppler Current Profiler (ADCP) profiles traced directly in the estuarine environment with the aim of studying the relationship between data with and without tidal influence. For flows obtained directly at the mouth, the value reaches 70.44m3/s, while the average freshwater flow for the same location based on ANA data was 651.85m3/s. The comparison of flows using the salinity parameter opened the way for interpretations of the influence of the tidal water column on the freshwater flow in the region, showing the strong change in behavior in different environments.