This paper is an exploratory study to bring upon discussion some technical (that is, in this case, both urbanism and environmental engineering criteria) subsidies in order to build a Metropolitan (urban, mostly) Drainage Plan for the Metropolitan Region of Belém (RMB), Brazil. Located in the Amazon Region, North Brazil, RMB is the metropolitan area with the highest levels of domiciles in slums and shantytowns, according to 2010 official data. Its territory is a plain site, with low declivities and high pluviometry rates, and its floodplains have been precarious for decades. Serious sanitation problems may be found in those areas, which are extensive in territory. GIS is a resource used alongside with theoretical issues to discuss the case of RMB flooding phenomenon, considered as its main environmental risk problem. Finally, directives are listed, recommending combined and systemic use of both structural (highly artificial, concrete-based drainage structures) and non-structural (less artificial, more based on water and basins management, soil infiltration and natural processes, such as retention and flow), differentiated by the morphological characteristics of urban occupation and demographic densities.
