Geomorfologia e dinâmica hidrológica do rio Paraguai no trecho entre Porto da Manga e Porto Murtinho-MS

Abstract

The Paraguay River is one of the three major fluvial systems that make up the La Plata River Basin. The Paraguay River Basin can be subdivided into three main sections: the Upper Paraguay Basin (UPB), the Middle Paraguay, and the Lower Paraguay. Within the UPB alone, the Paraguay River extends approximately 1,693 km, much of which flows through the Pantanal. Despite its environmental, economic, and social significance, the fluvial system of the Paraguay River remains poorly understood. In this way, the present study aims to analyze the hydrological dynamics of the channel and the geomorphology of the floodplain of the Paraguay River in the stretch between Porto da Manga and Porto Murtinho-MS, located within the Pantanal basin, in a segment approximately 465 km. Using remote sensing data and geoprocessing techniques, the geomorphological segments along the current meander belt of the Paraguay River in the Pantanal were mapped, and flow variations along the channel, channel-floodplain interactions, and structural controls that influence the system’s hydrodynamics were analyzed. As a result, six geomorphological segments were identified along the current meander belt of the Paraguay River: the Porto Esperança, Forte Coimbra, Bahia Negra, Barranco Branco, Fecho dos Morros, and Porto Murtinho meander belts. The results revealed that the hydrological dynamics of the Paraguay River do not follow a continuous pattern of progressively increasing discharge, as predicted by the river continuum concept. Instead, there is a complex interaction between the channel and the floodplain, redistributing water differently along the analyzed stretch. Hydraulic bottlenecks, such as the Fecho dos Morros, act as natural barriers that restrict river flow, promote temporary water storage, and significantly impact discharge regulation. The analysis also identified drought periods in the early 1970s and 2020s, which exhibited similar patterns but important differences in discharge recovery, especially in 2023. The hydrological balance revealed the presence of predominantly tributary sections, where discharge increases due to tributary and lateral inflows, and distributary sections, where discharge is lost to the floodplain, highlighting the strong integration between the channel and the floodplain. Thus, this study demonstrates that the hydrological dynamics of the Paraguay River are highly influenced by connectivity processes between the channel and the floodplain and by structural controls. Understanding these interactions is essential for improving knowledge of the Pantanal’s hydrological dynamics and supporting effective water management and conservation strategies for the floodplain.