Environmental sustainability of water resources in the city of Rio de Janeiro, Brazil

Objective. To propose an urban water sustainability index based on indicators that may serve as a foundation for developing planned actions concerning water resources. Methods. Eleven indicators (covering aspects of water and sewage) were selected based on the parameters of Brazil's actions Water and Sanitation Information System (Sistema Nacional de Informacao sobre Saneamento) for the years 2000 and 2001. A score and a weight were assigned to each indicator. Based on that, the urban water sustainability index (UWSI) was calculated, using the formula UWSI = product (I-i(pi)), where I-i is the score attributed to each indicator i, ranging from 0 to 100, and pi is the weight for each indicator Sigma(i=1)(n) P-i = 1, where n is the number of indicators considered). The lowest water quality is indicated by an index value of 0, and the best by an index value of 100. Results. The urban water sustainability index for the city of Rio de Janeiro was 58.99 in 2000, and it rose to 59.57 in 2001, indicating water of good quality in both those years. Conclusions. The improvement in the quality of the water resources between 2000 and 2001 in the city of Rio de Janeiro is possibly the result of the implementation, in the 1990s, of an environmental management program in the Rio de Janeiro region. Environmental planning that includes rational use of water resources and methods to prevent their destruction is crucial to sustaining society.