A discharge stationary model for the Pará-Amazon estuarine system

Abstract

Study region: This study presents the empirical observations and numerical model of Fluvial Discharge (Q) used to estimate the magnitude of the continental input of the Pará River into the Atlantic Ocean. The Pará River is a component of the Amazon hydrographic network in northern Brazil. Study focus: A Q box model was developed to estimate the magnitude of the continental input of the Pará River toward the Atlantic Ocean. In the present study, the box model consists of the sum of the different components that contribute to the total input of freshwater into the system, and assumes a stationary condition, in which the Q values (box model inputs) feed the model with values that are constant over time. New hydrological insights for the region: The mean Q value estimated for the Pará River was 20,946 m3 s−1. The box model indicated the Araguaia-Tocantins hydrographic basin contributes approximately 52 % of this input, and the Amazon basin, 44 % of the Q estimated for the Pará River. Based on the historical Q series, it has been found that QPARÁ RIVER freshwater inputs vary seasonally. In the first half of the year there is a greater contribution of water from the Araguaia-Tocantins Basin. However in the second half of the year the largest contribution is from the Amazon Basin. At 664 km3 year−1, the annual mean discharge of the Pará River is the fifth largest of the world’s principal river systems. Keywords: Major rivers, Amazon continental shelf, Tropical Atlantic Ocean