Sabo Works: A Pioneering Experience in Brazil

This paper deals with the erosion and sediment control engineering works (“sabo works” to use a Japanese term), built along the Pedras River and its tributary to protect the installations of an oil refinery against the destructive action of debris flows. The refinery is located in Cubatão, State of São Paulo, Brazil, at the foot of the steep hill slope of the “Serra do Mar” mountain range. Officially called Refinaria Presidente Bernardes Cubatão (RPBC), it is an important unit of PETROBRAS, the largest oil company in Brazil, mainly for its characteristics of being the most complex one, producing a great variety of products. Its annual production is about 200,000 barrels per day. As the area is densely occupied by chemical and processing industries, the discharge of pollutants to the atmosphere has affected the vegetation of the hill slopes, causing its degradation, either by direct incidence or by acid rains. Although an aggravating factor, this may not be solely responsible for the landslides and debris flows, since the geological inspections of the river deposits have shown that these phenomena has been recurrent in the last thousand years. In addition an old road, “Caminho do Mar”, which crosses the basin along the mountain range, was at that time out of use and without proper maintenance, particularly as far as its drainage system was concerned. The excess water drained by the road poured into the basin, increasing the erosion problems, and the amount of loose material that was easily incorporated to a debris flow. Preservation of the natural landscape, against erosion and sediment transport, and protection of the natural vegetation were also of basic concern in the design of such “sabo works”. Although “sabo works” have a long history in countries like Austria and Japan, it is a pioneer activity in Brazil, that benefits from the world-wide experience regarding economy and effectiveness. It is worth mentioning the technical visit carried out by some of the authors to Japan, in 1996, to learn from the Japanese expertise in this field of knowledge.