Análise e compartimentação morfométrica da bacia hidrográfica do Rio Cauamé, Roraima, Brasil

Abstract

The implementation of Water Resources Management Instruments depends on a thorough diagnosis, providing a comprehensive view of various analysis themes. The Cauamé River Basin is located in the northern region of the state of Roraima, within the municipalities of Alto Alegre and Boa Vista, encompassing part of the urban area of Boa Vista, the state capital, as well as part of the urban area of Alto Alegre. Situated in a significant socioeconomic context, about one-third of the state's population resided in the basin area in 2010. It is a sub-basin of the Branco River Basin, which is part of the Amazon Basin. The objective of this research involves the diagnosis and analysis of the morphometric compartmentalization of the basin, resulting in a Geographic Database accessible via a Web Geographic Information System (GIS). Through the geoprocessing of remote sensing inputs, the drainage network and the boundaries of the basin and its sub-basins were delineated. The sub-basins were delimited and coded according to the Otto Pfafstetter system. A set of morphometric parameters of the sub-basins was calculated, resulting in a Compactness Coefficient (Kc) ranging from 1.14 to 2.19 with an average value of 1.40; Circularity Index (Ic) with values ranging from 0.21 to 0.77 with an average of 0.52; Altimetric Range (H) with a minimum value of 7 meters and a maximum of 383 meters, predominantly ranging between 7 and 82 meters. The average value was 44 meters; Basin orientation predominantly between 90º and 180º. The average value found was 153º; Drainage Density (Dd) with values between 0.35 km/km² and 6.0 km/km², with an average of 1.3 km/km²; Average length of surface runoff with values ranging from 0.04 km to 1.29 km, with an average of 0.44 km; Stream sinuosity (sin) with values ranging from 1.00 to 1.93 and an average value of 1.2; Average channel length with values ranging from 0.19 km to 3.98 km and an average value of 1.0 km; Drainage area with results reaching 82.3 km² and an average value of 10.5 km²; Relief Ratio (Rr) ranging between 2 and 175 m/km, with a wide predominance of values between 2 and 12 m/km. The average value is 15 m/km; Rugosity Index (Ir) with values found between 0.007 and 0.426, obtaining an average of 0.053. Using multivariate statistics, three morphometric compartments were defined: Group 01 - Basins with the greatest average channel length: comprising 61 sub-basins. This group stands out for having the lowest drainage density, the lowest altimetric range, and the lowest rugosity index; Group 02 - Basins with the highest drainage density: comprising 214 sub-basins. This group is also characterized by the shortest average surface runoff length and the shortest average channel length; and Group 03 - Basins with the highest altimetric range: comprising 22 sub-basins. This group is also characterized by having the longest average surface runoff length and the highest rugosity index. The dataset produced was organized into a Geographic Database and made accessible through a Web GIS implemented using the I3Geo platform. The results of the morphometric analysis indicated that the regions of the basin should not be treated homogeneously, as evidenced by the morphometric variations found in the sub-basins. The generated products have a pioneering character and enable advances in the quality of water resource management in the basin, opening possibilities for new studies.