Potencial erosivo e características das chuvas de São Gabriel, RS, de 1963 a 1993

Abstract

RESUMOConhecer a erosividade da chuva é fundamental para ações de controle da erosão em cada região, devido à sua alta variabilidade temporal e espacial. O objetivo deste trabalho foi determinar a erosividade, os padrões hidrológicos, o coeficiente de chuvas e o período de retorno das chuvas de São Gabriel, RS, com base nos dados de registro dos pluviogramas diários para o período de 1963 a 1993. Para cada chuva considerada erosiva foram anotados o tempo e a altura de cada segmento com mesma intensidade, sendo calculados a erosividade pelo parâmetro EI 30 , seus totais mensais e anuais e os padrões hidrológicos das chuvas, o coeficiente de chuvas, o período de retorno e a probabilidade de ocorrência. O período de outubro a maio concentra 75% da erosividade anual, com pico maior em fevereiro (712 MJ mm ha -1 h -1 ). Os padrões avançado, intermediário e atrasado têm 52, 21 e 27% do número de chuvas erosivas perfazendo 55, 21 e 24% do volume médio anual e 58, 21 e 21% da erosividade média anual, respectivamente. A erosividade média anual da chuva para São Gabriel é de 6432,4 MJ mm ha -1 h -1 (Fator "R" da USLE) com um período de retorno de 2,7 anos e probabilidade de ocorrência de 37,5%.Palavras-chave: padrões hidrológicos de chuva, índice EI 30 , erosividade, fator R Erosive potential and rainfall characteristics of São Gabriel, RS, Brazil, from 1963 to 1993 ABSTRACT The knowledge of rainfall erosivity is fundamental for actions of erosion control in each region, due to its high variability in time and space. The objective of this study was to determine the rainfall erosivity, the hydrological patterns, the rainfall coefficient and the return period of erosive rainfalls of São Gabriel (RS, Brazil), based on the period of 1963 to 1993. For each erosive rainfall, the hour and the height of each rainfall with the same intensity were digitalized, and the EI 30 index, the monthly and annual totals, the hydrological pattern, the rainfall coefficient, the return period and its probability occurrence were calculated. The period of October to May concentrates 75% of the annual erosivity, with larger peak in February (712 MJ mm ha -1 h -1 ). The advanced, intermediary and delayed patterns have 52, 21, and 27% of the number of erosive rainfalls, corresponding to 55, 21 and 24% of the annual volume of erosive rainfalls and 58, 21 and 21% of the mean annual erosivity, respectively. For São Gabriel, the mean annual rainfall erosivity index is 6432.4 MJ mm ha -1 h -1 (Fator "R" of USLE), with a return period of 2.7 years and probability occurrence of 37.5%.

Water erosion associated with rainfall patterns in the extreme South of Bahia in eucalyptus post-planting

“…For Eltz et al (2013), advanced rainfall pattern tends to cause lower soil losses since surface sealing, particle disintegration, and particles transport are reduced at the beginning of the rainfall event, when compared with the other patterns. (Figure 9) show that soil losses were more directly associated with the advanced rainfall pattern.…”

Spatial Interpolation of Rainfall Erosivity Using Artificial Neural Networks for Southern Brazil Conditions

“…The difference in netErosividade RS databases and in the erosivity databases from the literature can explain the variation of the values of erosivity by both methods. For instance, Eltz et al (2013) pointed to the difference between the periods of databases to justify the difference between the erosivity value estimated by them and Cemetrs (2011), since they used the period from 1963 to 1993 and Cemetrs (2011) used the period from 1976 to 2005. Thus, the difference in the estimates performed by netErosividade RS (15.6 %) may be associated with the fact of databases to calculate the rainfall erosivity were not the same.…”

Erosive rainfall in the Rio do Peixe Valley: Part III - Risk of extreme events

“…The value of R corresponds to the average of the annual erosivity EI30 index, and is evaluated by using a long pluviographic data series (Cassol et al, 2008;Silva et al, 2009). Several studies show that there is a large annual variation in rainfall erosivity (Eltz et al, 2013;Valvassori & Back, 2014;Back et al, 2016).…”