Análise multitemporal e morfodinâmica no entorno da confluência do rio Solimões com o rio Negro

Abstract

The Solimões River, in relation to the geomorphological development, is considered young because it possesses considerable energy and erosive potential. These characteristics allow the landscape of the Amazonian scenario to be constantly transformed as a function of existing river dynamics, which, although not an exclusivity of the region, has expressiveness in terms of magnitude scale and complexity of factors. Present in the dynamics of all the fluvial channels, erosion, transport and deposition of sediments are processes that, although working simultaneously, do not present in a homogeneous way along the longitudinal profile of the Solimões river. There are segments of the river in which the erosive process prevails and in others the deposition process. In the same way, it is common for each hydrological regime, characterized in the Amazon region by periods of floods and ebbing, it is perceived that the erosive and depositional processes alternate spatially. At first, inadvertently, one can think that, because it is a natural phenomenon, there are no social and economic impacts for the region. However, the implications of fluvial dynamics on the Solimões River can reach different scales, whether local or regional. The reason for this is the importance that the Solimões river, like the other rivers of the Amazon, has for the residents, mainly riverside, and for the transport of loads and passengers in the region. Therefore, this work presents the transformations in the landscape and the evolution of the Solimões River in the stretch located approximately 15 kilometers upstream of its confluence with the Negro River. The area covers the whole extension of the island of Marchantaria, a relevant natural element that participates directly in the channel dynamics. To cover all the complexity of this type of study, it is opted for a systemic approach to understanding natural phenomena and their effects on social and economic spheres. In order to show the transformation of the landscape, one of the most important categories of Geography analysis, and the evolution of the Solimões River in the mentioned section, it is used the satellite images of the Landsat space program, whose main objective is the observation of terrestrial natural resources. Three images were used, implying a temporal scale of 23 years (1995, 2005 and 2018). In order to corroborate the data obtained through Remote Sensing, bathymetric surveys were carried out in five points of the river. From the charts of the bathymetry and the interpretations of the satellite images, it is concluded that this section of the river Solimões is undergoing morphological changes in its bed, sedimentating in the right margin and eroding in the left margin. With regard to the socioeconomic impacts, it was verified that the larger vessels, due to the greater depth, navigate the left bank, suggesting a greater expenditure of fuel and time.