ORIGINAL ARTICLE Use of geographic information system (GIS) in the characterization of the Cunha Canal, Rio de Janeiro, Brazil: effects of the urbanization on water quality Renata Coura Borges • Fa ´bio Ventura dos Santos • Vanessa Godoy Caldas • Celso Marcelo Franklin Lapa Received: 6 May 2013 / Accepted: 26 June 2014 / Published online: 17 July 2014 Ó Springer-Verlag Berlin Heidelberg 2014 Abstract The Cunha Canal Watershed, located in the city of Rio de Janeiro, suffered an intense environmental degra- dation over the last decades caused mainly by the rapid urban growth. However, this pronounced growth deteriorated the existing socio-environmental problems. This article intended to assess the pollution of the waters of Cunha Canal, caused by the disposal of domestic sewage and industrial effluents. The data analyzed were monitored in two different periods. Chemical parameters such as dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, total phosphorus and amonniacal nitrogen were measured. The results show that the water of Cunha Canal is altered and degraded, probably due to the intense urbanization of the watershed environs. Increase in the water quality was not observed. Therefore, an alternative to reduce the pollution in the area could be the construction of a sewage treatment plant. Keywords Water pollution  Dissolved oxygen  Biochemical oxygen demand  GIS Introduction The scarcity of water has become a major issue due to the fast population growth, summed to the degradation of water resources caused by anthropic actions over the world (Rebouc ¸as et al. 2006). According to estimative of the Brazilian Ministry of Environment, in 2032 circa of 5.5 billion people will be living in areas with moderated or serious absence of water. Nowadays, more than a billion people live in conditions of insufficient availability of water to human consumption (MMA 2007). In Brazil, despite the country has the highest water avail- ability of the planet, i.e. 13.8 % of fresh water of the world, the reality is no different. The preservation of water resour- ces, in quantity and quality, however, is a complex problem whose resolution depends on the articulation and joint of efforts of the public sector, especially those in possession of instruments to control the use and occupation of soil (municipalities and planning agencies) and supervision and monitoring the water quality and water pollution (environ- mental state entities), aimed mainly at controlling the occu- pations and minimize impacts on water resources (Andreoli and Carneiro 2005). The urban sprawl occurring in Brazilian cities and in other parts of the world has its own bearing on the envi- ronment, where severe pollution of air, soil or water is highly expected. According to Castelo (2007), more than 50 % of world population lives in urban areas. In Brazil, this number is around 70 % (IBGE 2008). The over-growth of urban areas occurred in an uncontrolled way, without concern about natural environment, which caused reduc- tion in well-being and quality of life in these places. The reasons behind the pollution of watercourses are due to different facts: the first is related to the growing population and the urban sprawl, the second being the industrial development (Furquim 1978). The Cunha Canal watershed is a region surrounded by 133 slums and 24 illegal settlements. From its 7,015.99 hectares but only 6 % are of natural areas. The massive absence of vege- tation creates a huge urban heat island upon the watershed area. In terms of atmospheric pollution this watershed is in the most Present Address: R. C. Borges (&)  F. V. dos Santos  V. G. Caldas  C. M. F. Lapa Instituto de Engenharia Nuclear, Cidade Universita ´ria, Ilha do Funda ˜o, Rua He ´lio de Almeida 75, Rio de Janeiro, RJ 21941-906, Brazil e-mail: renatacouraborges@hotmail.com 123 Environ Earth Sci (2015) 73:1345–1356 DOI 10.1007/s12665-014-3493-1