Sobradinho Reservoir: Governance and Stakeholders

Abstract

The São Francisco drainage basin covers 7.6 % of the Brazilian territory and has tremendous economic, social, and cultural importance for the country. About 60 % of its watershed is in the semi-arid region, which is characterized by having critical periods of drought. To regulate the river flow and to generate power, a cascade of hydropower plants was constructed on the São Francisco River. Among them is the Sobradinho Reservoir, which has an interannual water storage capacity to meet multiple water uses and adds about 4 billion kW of energy per year to the Brazilian northeast. In recent years, the average unregulated flow in the Sobradinho Reservoir has been lower than the historical average. The lowest average annual unregulated flow in the Sobradinho Reservoir occurred in 2014, and the first months of 2015 did not point to better conditions. The current and unfavorable hydrologic situation of the São Francisco Basin represents real governance challenges for Brazil. The minimum outflow from the Sobradinho Reservoir has been reduced several times to ensure that the needs for the multiple uses are met. Today, the Sobradinho Reservoir operates with a minimum outflow of 900 m3/s. Because of these reductions, there was a cumulative gain of 44.7 % in the active storage of the reservoir. If the mitigation measures that allowed reducing the minimum outflow had not been implemented, this reservoir would have fully depleted of its active storage by November 2014.