Vulnerabilidades e potencialidades da microbacia hidrográfica do igarapé do Mariano na zona de transição e expansão urbana de Manaus-AM

Abstract

This thesis analyzes the vulnerabilities and the potentialities of the Mariano creek watershed in the urban expansion and transition zone of Manaus-AM. In general, the aim was to investigate the state of vulnerabilities and potentialities of the watershed caused by the pressure of the city's urban expansion. Specifically, the natural attributes of vegetation, soil, climate, hydrography and land use were identified and analyzed taking into account anthropogenic interventions, implications and problems in the watershed; subsequently, the information on the hydrographic ecosystem was correlated in a Geographic Information System (GIS) and, finally, the Synthesis Chart of Vulnerabilities and Potentialities of the Mariano creek watershed was constructed. The study is structured in four chapters, the first of which deals with the use and occupation of the urban site of Manaus, determined by two economic moments: the exploitation of rubber, which led to changes in the urban space, and the establishment of the Manaus Free Trade Zone, which led to a true rural exodus, culminating in more than 50% of the inhabitants living in slums and the urban micro-basins being degraded. The second chapter deals with research and planning in urban and rural watersheds, their importance as a planning and management unit in the face of water resource degradation. It presents a study of the micro-watershed and its classification and discusses geotechnologies with the introduction of Remotely Piloted Aircraft (RPA) in watershed research and planning, using ecodynamics and morphodynamics as tools to identify levels of vulnerability and potentialities. The third chapter deals with the forms of land use and occupation that have been consolidated in the Mariano watershed, which has a low population density. Despite the vectors of the Adolpho Ducke Environmental Protection Area and Tarumã/Ponta Negra in the watershed, anthropogenic alterations are degrading the hydrographic network. For a more detailed analysis, the watershed was mapped and compartmentalized into the higher stream with access via the AM-010 (Manaus-Itacoatiara), the middle stream with access via the BR-174 (Manaus-Roraima) and the lower stream with access via Avenida Cláudio Mesquita. These major roads facilitate and accelerate occupation without proper planning. The fourth chapter presents the current scenario of the watershed caused by the pressure of urban expansion using the Synthesis Chart of Vulnerabilities and Potentialities. A study was carried out in 2007 and 2015 using orthophotos, and in 2022 with CBERS 04A imagery based on six classes of land use and occupation supported by fieldwork with aerophotogrammetry carried out with ARP and morphographic and morphometric data to identify potentialities and vulnerabilities. The results showed that the watershed has 81.08% potentiality with a predominance of forestry, 1.41% of intermediate areas that are in equilibrium and 16.88% of areas of vulnerability. The conclusion is that the occupation scenario in the Mariano micro-basin repeats the same model as the igarapés in the urban area of Manaus: with no planning and in the absence of public authorities, transformations that infringe environmental laws leave the hydrographic ecosystem vulnerable and likely to become an open sewer in the near future.