ASSESSMENT OF LANDSCAPE CHANGES IN THE ANAVILHANAS ARCHIPELAGO DURING THE FLOOD PEAK AND DROUGHT EVENTS IN THE RIO NEGRO, CENTRAL AMAZÔNIA, BRAZIL

Abstract

This article estimates for the ï¬rst time the extents of the landscape changes in the Anavilhanas Archipelago, as registered by satellite images acquired during the flood peak and drought events ever recorded in the Negro River (in Portuguese, "Rio Negro"). The Anavilhanas constitutes the second largest group of freshwater islands in the world, comprising a complex pattern of islands, channels, lagoons, swamps, beaches and sandbanks, which dramatically changes during the seasonal periods of high and low waters. The results showed that approximately 1,700 Km² of flooded area in the high water period were reduced by about 50% during the low water period, allowing the appearance of more than 800 Km² of beaches, sandbanks, and shallow submerged sandbanks. The extent of these seasonal landscape changes associated with the pulses of rising and descending waters are dominant environmental factors aff ecting the rich biota of the archipelago, which is refuge of a diversiï¬ed fauna and flora. Therefore the generated maps can be useful information for the hydrological modelling studies and for environmental monitoring of the region.