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Title: Rainfall erosivity and rainfall return period in the experimental watershed of Aracruz, in the Coastal Plain of Espirito Santo, Brazil

Author
item MARTINS, S - Universidade Federal De Lavras
item AVANZI, J - Universidade Federal De Lavras
item SILVA, M - Universidade Federal De Lavras
item NILTON, C - Universidade Federal De Lavras
item Norton, Lloyd
item FONSECA, S - Universidade Federal De Lavras

Submitted to: Revista Brasileira De Ciencia Do Solo
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2010
Publication Date: 8/1/2010
Citation: Martins, S.G., Avanzi, J.C., Silva, M.L., Nilton, C., Norton, L.D., Fonseca, S. 2010. Rainfall erosivity and rainfall return period in the experimental watershed of Aracruz, in the Coastal Plain of Espirito Santo, Brazil. Revista Brasileira De Ciencia Do Solo. 34:999-1004.

Interpretive Summary: The power of rainfall to cause soil erosion is an important property to know for conservationists. It varies greatly from place to place and from year to year. In order to plan effectively, a conservationist must know how often they can expect a storm to return that can cause severe erosion. This prediction is done through studies of historically measured data. For an area along the Atlantic coast of South America north of Rio de Janeiro Brazil we studied historical data to calculate the total erosive force of rainfall and the return period for severe storms. At Aracruz, Espirito Santo State, Brazil, we found that 85% of the most severe storms occurred during October to March although their total rainfall was considerably less than half the annual total rainfall. The total average rainfall erosion potential was found to occur just over every third year. The significance of these findings is that land-users should avoid disturbing the land from October to March and schedule major activities to avoid storms with a high potential to prevent soil erosion.

Technical Abstract: The knowledge of the factors influencing water erosion is relevant to land management practices. Rainfall, expressed by rainfall erosivity, is very important among the factors affecting water erosion. Thus, the objective of this study was to determine rainfall erosivity and return period for the Coastal Plains region, near the town of Aracruz, Espírito Santo state, Brazil based on available data. We used measured historic rainfall data in order to calculate rainfall erosivity. This data was collected at every 5 minute intervals at weather stations from January 1998 to July 2004 at Aracruz Celulose S.A. Individual rainfall and erosivity values were correlated in order to obtain an equation that allowed an extrapolation of data to provide individual erosivity for a 30-year period. Using this data the annual average rainfall erosivity in Aracruz was 8,536 MJ mm ha-1 h-1. The October to March period was found to be the most critical with 85% of total annual erosivity occurring then. Annual erosive rainfall represented 38%, however, its volume represented 88%. The annual average rainfall erosivity return period was estimated to be 3.4 years.