Environmental diagnosis of the lower course of the Gigante river basin (Amazonas - Brazil).
The watershed is a complex system that goes beyond the drainage network, involving all the ecosystem aspects within its limits. Despite the set of ecohydrological functions that its components play in the protection of water resources, especially the vegetal cover, hydrological systems are the ecosystems that suffer the most changes due to anthropic activities, notably when inserted in the urban environment. Thus, this work aimed to perform the environmental diagnosis of the lower course of the Gigante river basin, in Manaus-AM. We carried field visits, collecting and registering information about the study area, applying check-list, interaction network and interaction matrix methods. Through the environmental diagnosis, we evaluated that the low course of the Gigante River presents areas where native vegetation has been suppressed, including permanent preservation areas, triggering several impacts of other orders, such as exposure and waterproofing of the soil, silting, introduction of exotic species, excess aquatic vegetation, effluent and solid waste. The proposed mitigation measures were to eliminate the emission of effluents and deposition of solid wastes, to remove the invasive species and to lead the natural regeneration and/or the enrichment of the area.