Evaluation of Insertion and Conservation Aspects Of Rain Water Detention Basins in Two Mid-Sized Municipalities in Brazil

In the pursuit of mitigating the impacts of urbanization on superficial drainage and infiltration of rainwater, the compensatory techniques in urban drainage emerge in the 70’s decade. Widespread in Europe and North America, in the Brazilian scenario these techniques have strengthened from the 90’s decade, with emphasis on the detention basins implantation - unique structures for controlling peak flows with great return periods, especially in metropolitan regions. In the last decade, this trend intensified in some mid-sized cities and the construction of these basins has become an obligation for new urban developments. Within this context, the objective of this article was to evaluate 50 detention basins deployed in the urban environment in the municipalities of Araraquara and São Carlos (São Paulo State, Brazil), with emphasis in the urban insertion, maintenance and integration of these units with its surroundings.The methodology adopted for this visual evaluation was composed of Google Earth images analysis, in loco observations and application of evaluation criteria, such as relative position, visibility, isolation, conservation and functionality. Aspects of design and construction were also evaluated. It was possible to identify similarities and discrepancies of the insertion and maintenance of the studied basins. Thus, from the visual analysis, it was observed a tendency to deploy these units isolated of its surroundings, without any integration with urban space and strictly focused on the hydrological function. As for the conservation aspect, most of the evaluated units presented excessive vegetation and deposition of solid wastes. In some cases, the presence of permanent water blade and entrainment of sediments inside the basin was observed. In general, the conservation status of the detention basins under the municipal public authority’s responsibility has proved to be precarious and inappropriate regarding the functionality of the units and their proximity with residences; contrary to the private managed basins that showed more adequate conditions to be part of the urban environment. The problems observed may compromise de expansion of the use of these units in the future.