Validação do modelo WEPP na predição de erosão hídrica para condição edafoclimática da região de Viçosa-MG / WEPP model validation in the prediction of water erosion for edaphic climatic conditions in the region of Viçosa-MG

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The sensitivity analysis of the WEPP model demonstrated that for the Brazilian edaphic climatic conditions the most critical parameters from the soil are: the erodibility interril (Ki), the erodibility in rill (Kr), the critical shear strength (τc) and the effective hydraulic conductivity (Ke). Through is of fundamental importance the evaluation of the equations used for the determination of these parameters, with the objective of improve the estimation of the soil and water in the WEPP model. Because of that, the objective of this work were to evaluate the soil and water losses in experimental plots submitted to natural rain conditions; to compare values of Ki, Ke, Kr and τc, obtained experimentally with the values generated by the equations used in the WEPP model and to validate it by the comparison of the soil and water losses obtained in experimental plots with the ones estimated using the parameters values from the soil (Ki, Kr, τc and Ke), obtained experimentally as the input data in the model. To reach the objectives proposed six plots were installed with different soil management planning in the Latosolic Distrofic Tb Haplic Cambisol, for the determination of the soil and water losses under natural rain conditions for the period of five seasonal crops. Also it was done the determination of the Ki, Kr, τc and Ke values for two types of soil (Latosolic Distrofic Tb Haplic Cambisol and Red Yellow Argisol), which were compared to the values estimated by the equations of the WEPP model. The soil and water losses obtained in the experimental plots were compared to those estimated obtained using the WEPP model for the same conditions of soil, management and declivity of the plots being used the input values of Ki, Kr, τc and Ke obtained experimentally as well values generated internally by the model. The values of Ki, Kr, τc and Ke obtained experimentally for the Argisol were of 3,06176x106 kg s m-4, 0,0268 kg N-1 s-1, 0,495 N m-2 and 7,3 mm h-1, respectively and for the Cambisol of 1,26433 x106 kg s m-4, 0,0108 kg N-1 s-1, 3,481 N m-2 and 13,3 mm h-1 respectively. The estimate for the soil loss showed average error of 1,69 kg m-2, when using the experimental parameters and of 6,87 kg m-2 using the values generated by the equations from WEPP. The estimate of the water loss showed average errors of 174,90 and 410,67 mm, considering experimental data and the ones generated by the model respectively. The results obtained allowed to conclude that the Argisol when compared with the Cambisol, have more susceptibility to erosion; the equations of the WEPP model superestimate the values of erodibility in interril and in the rill and subestimate the values of the critical shear strength and the effective hydraulic conductivity for the Cambisol; for the Argisol, superestimate erodibility in the interril and critical shear strength and subestimate erodibility in the rill and effective hydraulic conductivity. The utilization of the parameters from soil, obtained experimentally as input data of the WEPP model improved in 306% the estimates of the soil losses and in 135% the water losses; and for the water losses, even considering the adjustment of the effective hydraulic conductivity, the deviation from the estimates related to the experimental data from the five seasonal crops evaluated, are much higher then the values observed experimentally.

ASSUNTO(S)

erosão em sulcos e entressulcos planejamento integrado dos recursos hidricos erosion estabilidade do solo soil stability perdas de solo soil losses

ACESSO AO ARTIGO

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