Surface runoff in six years of rehabilitation of two areas after bauxite mining in Southeastern Brazil

The analysis of surface runoff pre-mining and during six years of rehabilitation with Eucalyptus plantation, post-mining, in bauxite mining areas was the central objective of this work. Surface runoff was monitored from January to May before mining and in the same months from the first to the sixth year of rehabilitation, being collected in seven plots in two bauxite mining areas in southeastern Brazil. The factors that interfere with runoff were characterized in all periods, statistically compared by the Wilcoxon test and submitted to principal component analysis (PCA). The total surface runoff in the five months before mining was 1.74 to 14.06 times greater than the runoff in the same months in the six years of rehabilitation. The average percentage runoff was <1% of the precipitation in all rehabilitation periods, in contrast before mining 1.3% of the precipitation of 556 mm became surface runoff. The highest slopes of the regression were for the first year of rehabilitation and for the pre-mining period, showing a greater influence of precipitation on the generation of surface runoff. Soil, litter and vegetation characteristics were the most explanatory factors in the six-year PCA. Specific factors must be viewed with caution on micro scale in each year of rehabilitation of surface bauxite mines, due to soil heterogeneity and consequent vegetation, seeking to minimize the negative effects on surface runoff. Gap in knowledge about surface runoff percentages in six years of rehabilitation in Brazil and tropical areas was filled. Mine managers can more clearly define the priority factors in strategies to mitigate the effects of mining on the environment from the first to the sixth year of rehabilitation in surface mined areas.