Análise dos parâmetros morfométricos na bacia hidrográfica do Rio Pindaré - MA

Abstract

Rivers play an essential role in maintaining life and the balance of geosystems. Within the field of fluvial geomorphology, morphometric analysis is responsible for determining and evaluating the components of drainage networks in river basins. This specialty is based on the analytical method, which considers and characterizes the set of slopes and channels belonging to the relief. From this perspective, the measurements of these variables form the basis for the composition of morphometric parameters. The objective of this research is to analyze the morphometric characteristics of the Pindaré River basin, located in the central-western portion of the state of Maranhão. To achieve this, the methodological path followed consisted of: survey and analysis of bibliographic material; preparation of a cartographic base in a Geographic Information System (GIS) environment, ArcGIS®, version 10.2.2 by the Environmental Systems Research Institute (ESRI), and fieldwork. Thus, the parameters adopted were based on the classic literature of Horton (1945), Strahler (1952), Miller (1953), Schumm (1956), Christofoletti (1980), Alves and Castro (2003), such as: area, perimeter, drainage network, number of channels, total length of channels, maximum basin altitude, basin altimetric amplitude, main channel length, axial distance of the main channel, slope, drainage density, hydrographic density, maintenance coefficient, and shape index. In view of this, the results indicate that the main springs of the Pindaré River are located in the cities of Montes Altos and Amarante do Maranhão, in the Krikati indigenous land. At an altitude of 371 m, its drainage presents a dendritic pattern of 6th order hierarchy, according to Strahler’s classification (1952), with a regular drainage density of 0.53 km/km² and a hydrographic density of 0.114 km/km². Additionally, the Pindaré River basin demonstrated a strong influence of structural control, where rivers flow through structural elements and geological faults. Despite this, its main channel proved to be predominantly straight, with a sinuosity index of 1.57 and the presence of well-defined meanders restricted to the lower course. It was found that the main river runs about 466.3 km to its mouth, with a total drainage area of 40,280 km². Furthermore, the circularity index of 0.39 and the form factor of 0.21 reinforce the low susceptibility to flooding under normal rainfall conditions. The study area is predominantly characterized by the geological unit of the Itapecuru Group. Regarding the highlighted geomorphological class, they are the Dissected Plateaus, and in relation to pedological characteristics, the Dystrophic Red-Yellow Argisol predominates. This work aims to encourage the implementation of future measures to preserve and maintain riparian forests and surface water resources