Urban stormwater flood management in the Cordeiro watershed, Sao Paulo, Brazil: does the interaction between socio-political and technical aspects create an opportunity to attain community resilience?

In the urban Cordeiro watershed, São Paulo, Brazil, the impervious surface has reduced stormwater infiltration and the drainage system has become insufficient. Engineering firms have been contracted, under government supervision, to implement the construction of six water reservoirs in order to decrease the frequent flood events in the watershed. The main purpose of this article is to contribute to the study of the relationship between technical and socio-political aspects of urban stormwater drainage, as technical solutions alone have proven to be insufficient. Research conducted in the area shows that residents and businessmen construct individual infrastructure to protect their homes and businesses, independent of any interaction with engineering firms or local government officials. Relevant literature suggests that stronger interaction among these stakeholders offers an opportunity to evolve from self-reliance into a collective strategy of resilience, enhancing the effectiveness of flood risk management practices

Influência da densidade populacional nas relações entre matéria orgânica carbonácea, nitrogênio e fósforo em rios urbanos situados em áreas com baixa cobertura sanitária Influence of the urban density in the relationship among carbonic organic matter, nitrogen and phosphorous in small rivers with low sanitation coverage

O objetivo principal deste trabalho é a análise da variação da relação entre a matéria orgânica carbonácea (representada pelas Demandas Biológica e Bioquímica de Oxigênio), Nitrogênio Total Kjeldhal e Fósforo Total nas águas de pequenos rios urbanos cujas áreas de drenagem apresentem baixa cobertura sanitária. Para isso, foram selecionadas 4 bacias hidrográficas urbanas com ocupação residencial, densidade populacional entre 0 e 100 hab/ha e similaridade de condições naturais e de ocupação humana. Os resultados mostraram alterações importantes nas relações entre os conteúdos de matéria orgânica carbonácea, Nitrogênio e Fósforo indicando que, a partir de uma condição natural não urbanizada, mesmo pequenas densidades populacionais são capazes de alterar significativamente a qualidade das águas.<br>The purpose of this study is to evaluate the relationship among the carbonic organic matter (measured as Chemical and Biological Oxygen Demand), Total Kjeldhal Nitrogen and Total Phosphorous in small urban rivers with low sanitation coverage in its hydrographic basins. Four basins with similar natural condition and residential occupation but variable urban densities between 0 and 100 inhabitants per hectare were selected. The results show important changes in the carbonic organic matter, Nitrogen and Phosphorous relationships indicating that, compared with a natural condition, even low urban densities can significantly change de water quality