Rainfall erosivity and rainfall return period in the experimental watershed of Aracruz, in the coastal plain of Espirito Santo, Brazil

Abstract

SUMMARYKnowledge on the factors influencing water erosion is fundamental for the choice of the best land use practices. Rainfall, expressed by rainfall erosivity, is one of the most important factors of water erosion. The objective of this study was to determine rainfall erosivity and the return period of rainfall in the Coastal Plains region, near Aracruz, a town in the state of Espírito Santo, Brazil, based on available data. Rainfall erosivity was calculated based on historic rainfall data, collected from January 1998 to July 2004 at 5 min intervals, by automatic weather stations of the Aracruz Cellulose S.A company. A linear regression with individual rainfall and erosivity data was fit to obtain an equation that allowed data extrapolation to calculate individual erosivity for a 30-year period. Based on this data the annual average rainfall erosivity in Aracruz was 8,536 MJ mm ha -1 h -1 yr -1 . Of the total annual rainfall erosivity 85 % was observed in the most critical period October to March. Annual erosive rains accounted for 38 % of the events causing erosion, although the runoff volume represented 88 % of the total. The annual average rainfall erosivity return period was estimated to be 3.4 years.Index terms: kinetic energy, R-factor, USLE, recurrence interval, probability of occurrence.(

Erosividade das chuvas associada a períodos de retorno e probabilidade de ocorrência no estado do Rio de Janeiro

“…Martins et al (2010) encontraram para a região de tabuleiros costeiros do Espírito Santo Pr de 29,78 % e T de 3,4 anos. Carvalho et al (1989); (2) Roque et al (2001); (3) Colodro et al (2002); (4) Moreti et al (2003a); (5) Moreti et al (2003b); (6) Evangelista et al (2006); e (7) Almeida et al (2011). localidades da mesorregião metropolitana, com exceção para o período de retorno de 100 anos.…”

Spatial distribution of water erosion risk in a watershed with eucalyptus and Atlantic Forest

“…The details of all factors in Equation (1), which were represented in a 10-meter-resolution map, are described below. The data were analyzed with the software b) Soil erodibility factor (K) The K factor for each soil class in the studied watershed was determined by an earlier study which was carried out by Martins et al (2011). The K values used were 0.007, 0.017, and 0.0004 Mg h MJ -1 mm -1 for PA1, FX, and PA2, respectively.…”

“…The soil erodibility map was generated using results from field plots conducted and measured by Martins et al (2011). It is worthwhile to point out that the greater the erodibility value, the lesser the resistance of the soil to water erosion.…”

Heavy rainfall equations for Santa Catarina, Brazil

“…The power of rain to cause soil erosion is called rainfall erosivity (Cassol et al, 2008). Many studies quantifying rainfall erosivity have been published elsewhere, e.g., Moreira et al (2008), Bazzano et al (2007Bazzano et al ( , 2010 and Martins et al (2010). According to Bazzano et al (2010), knowledge on rain characteristics increases safety in the planning of soil conservation structures e.g., terraces, catchment areas, and of agricultural practices of soil conservation by maintaining the vegetation cover or by constructions (dams, drainage canals), and hydraulic flow structures for rainwater, justifying the determination of precipitation characteristics.…”