Fator erosividade da chuva–enxurrada correlacionado com a erosão e erodibilidade em um Argissolo Vermelho de Aquidauana (MS)
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Data
2016-07-28
Autores
Nagel, Pedro Luiz [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Um índice de erosividade da chuva que se destaque e auxilie na estimativa da erosão do solo é altamente desejável. O parâmetro EI30 é o mais utilizado no mundo, no entanto, inúmeros trabalhos nacionais têm comprovado a eficácia de modelos que envolvem a enxurrada. O trabalho foi desenvolvido entre dezembro/2012 a agosto/2014, em um Argissolo Vermelho, da unidade experimental de Aquidauana (MS), pertencente à Universidade Estadual de Mato Grosso do Sul (UEMS). Foram selecionadas 92 chuvas individuais erosivas para o cálculo dos modelos de erosividade, e coletados os dados de perdas de solo e de enxurrada provenientes da parcela padrão. Parâmetros de erosividade da chuva, da enxurrada e da chuva-enxurrada foram analisados por meio de regressão linear simples, múltipla e não-linear, com a finalidade de: (a) definir o fator erosividade para chuvas individuais na tentativa de avaliar a eficiência entre si de parâmetros da chuva, da enxurrada e da chuva-enxurrada, visando aprimorar o uso da EUPS, EUPSM e da EUPSR local, e (b) determinar o fator erodibilidade para o solo pesquisado. Portanto, concluiu-se que: 1) No âmbito da EUPS, o índice EI30 de Wischmeier e Smith foi convenientemente adequado para predizer as perdas de solo das chuvas individuais erosivas locais. Assim, a erosão de Aquidauana pode ser calculada pela expressão: A*=3,7323+3,1171.10-2.EI30, e o fator erosividade da chuva em questão deve ser calculado pelo emprego do índice de erosividade da chuva EI30; 2) Já no âmbito da EUPSM e da EUPSR, o índice de erosividade local, por ter resultado uma substanciosa e superior correlação com as perdas de solo por erosão quando comparado ao tradicional EI30, deve ser calculado pelo emprego do índice de erosividade da chuva-enxurrada A*=a+b.EI30+c.Vu, e 3) O valor do fator K da EUPS, para o Argissolo Vermelho de Aquidauana (MS), foi de 0,0312 t ha h ha-1 MJ-1 mm-1. Portanto, nas condições de parcela padrão, estima-se uma perda de solo de 236,62 t ha-1 ano-1, cujo valor está bem acima do valor máximo de perda de solo permissível (tolerância de perda de solo), que é de 6,00 t ha-1 ano-1. Sendo assim, recomenda-se o emprego dos demais fatores da EUPS (LS, C e P), para que a erosão do solo pesquisado fique aquém de sua tolerância, de forma a se trabalhar sob a égide da auto-sustentabilidade agrícola local.
An index of erosivity rainfall that can stand out and assist in the estimation of soil erosion is highly desirable. The EI30 parameter is the most widely used in the world; however, many national papers have proved the effectiveness of models that involve the runoff. This study was carried out between December 2012 to August/2014, in the Experimental Unit of Aquidauana (MS), State University of Mato Grosso do Sul (UEMS), in a Dystrofic Tropustult. A set of 92 individual erosive rainfalls were selected for the calculation of the erosivity models and collected the data of soil losses and runoff from the unit plot. Erosivity parameters from rainfall, runoff and rainfall-runoff were analyzed through simple linear regression, multiple and non-linear, with the purpose of: (a) define the erosivity factor for individual rainfalls in an attempt to evaluate the efficiency between the parameters from rainfall, runoff and rainfall-runoff, aiming to improve the use of the USLE, MUSLE and RUSLE local, and (b) determine the factor erodibility for the soil of unit plot. Therefore, it was concluded that: 1) In the context of USLE, the Wischmeier and Smith EI30 was conveniently suited for predicting soil losses of individual erosive rainfalls local. Thus, Aquidauana erosion can be calculated using the expression: A*=3.7323+3.1171.10-2 .EI30, and erosivity rainfall factor shall be calculated using erosivity index rainfall EI30; 2) By the other hand, in the context of MUSLE and RUSLE, the local erosivity index, that resulted in a substantial and higher correlation with soil losses by erosion when compared to traditional EI30, must be calculated by using the rainfall-runoff erosivity index A*=a+b.EI30+c.Vu, and 3) The value of the K factor of the USLE, for Aquidauana (MS) Dystrofic Tropustult, was 0.0312 t ha h ha-1 MJ-1 mm -1 . Therefore, the unit plot conditions, it is estimated a soil loss of 236.62 t ha-1 year -1 , value that is above the maximum allowable soil loss (soil loss tolerance) which is 6.00 t ha-1 year -1 . Therefore, it is recommended the other EUPS factors, such as LS, C and P, in order to study the soil erosion underneaths its tolerance to be worked under the local agricultural sustainability aegis.
An index of erosivity rainfall that can stand out and assist in the estimation of soil erosion is highly desirable. The EI30 parameter is the most widely used in the world; however, many national papers have proved the effectiveness of models that involve the runoff. This study was carried out between December 2012 to August/2014, in the Experimental Unit of Aquidauana (MS), State University of Mato Grosso do Sul (UEMS), in a Dystrofic Tropustult. A set of 92 individual erosive rainfalls were selected for the calculation of the erosivity models and collected the data of soil losses and runoff from the unit plot. Erosivity parameters from rainfall, runoff and rainfall-runoff were analyzed through simple linear regression, multiple and non-linear, with the purpose of: (a) define the erosivity factor for individual rainfalls in an attempt to evaluate the efficiency between the parameters from rainfall, runoff and rainfall-runoff, aiming to improve the use of the USLE, MUSLE and RUSLE local, and (b) determine the factor erodibility for the soil of unit plot. Therefore, it was concluded that: 1) In the context of USLE, the Wischmeier and Smith EI30 was conveniently suited for predicting soil losses of individual erosive rainfalls local. Thus, Aquidauana erosion can be calculated using the expression: A*=3.7323+3.1171.10-2 .EI30, and erosivity rainfall factor shall be calculated using erosivity index rainfall EI30; 2) By the other hand, in the context of MUSLE and RUSLE, the local erosivity index, that resulted in a substantial and higher correlation with soil losses by erosion when compared to traditional EI30, must be calculated by using the rainfall-runoff erosivity index A*=a+b.EI30+c.Vu, and 3) The value of the K factor of the USLE, for Aquidauana (MS) Dystrofic Tropustult, was 0.0312 t ha h ha-1 MJ-1 mm -1 . Therefore, the unit plot conditions, it is estimated a soil loss of 236.62 t ha-1 year -1 , value that is above the maximum allowable soil loss (soil loss tolerance) which is 6.00 t ha-1 year -1 . Therefore, it is recommended the other EUPS factors, such as LS, C and P, in order to study the soil erosion underneaths its tolerance to be worked under the local agricultural sustainability aegis.
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Palavras-chave
Perda de solo, Conservação do solo, Índice EI30, EUPS, EUPSM, EUPSR, Soil loss, Soil conservation, EI30 index