Avaliação do modelo de Green-Ampt-Mein-Larson em condições de campo

• Autor(a) principal: Zonta, João Henrique
• Data de Publicação: 2007
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/3692
• topic: Infiltração; Precipitação; Green-AMPT-Mein-Larson; Infiltration; Precipitation; Green-Ampt-Mein-Larson; CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA::ENGENHARIA DE AGUA E SOLO

Among the several equations that were proposed for simulation of infiltration, the Green-Ampt-Mein-Larson (GAML) model is one of the most used in hydrological studies as it is based on the physical processes that occur in the soil during infiltration. However, some of its parameters do not match the real situation of the process of water infiltration in the soil. Thus, the objectives of this work was to determine the infiltration rate (Ti) and cumulative infiltration (I) in the soil under field conditions, with and without mulch; simulate the process of water infiltration in the soil with the GAML model, using different methodologies for obtaining its parameters; and evaluate the model by comparing simulated with experimental results. The trials were carried out in a Podzol Tb Dystrophic Haplic Cambisol, using a rain simulator. Experimental plots of 0.7 m width and 1 m length directed the surface runoff to a collection box in which the runoff volume was measured by a Thalimedes logger. Infiltration was computed from the difference between the water volume applied on the plot and the volume of the collected runoff. Nine tests were carried out using the following precipitation intensities: 243, 245, 184, 170, 170 and 105 mm h-1 (soil with mulch) and 115, 103 and 100 mm h-1 (soil without mulch). Simulations were performed with the GAML model to test different combinations of proposals to determine the entry parameters: θS (saturation moisture or total porosity) and θW (saturation field moisture) as moisture values in the transmission zone; K0 (saturated soil hydraulic conductivity) and Tie (stable infiltration rate) as values of hydraulic conductivity in the transmission zone (Kw) and the matric suction relative to the initial moisture content (ψ(θi)), equations of Risse et al. (1995) to calculate ψf as a function of soil texture, and Cecílio (2005) to calculate the matric suction in the wetting front (ψf). The confidence index (c') proposed by Camargo & Sentelhas (1997) was used to evaluate the model. The Tie for the trials in soil with mulch was 40 mm h-1 on the average, whereas in soil without mulch was 20 mm h-1, indicating the probable effect of the surface crusting on Tie reduction. As for the simulation of infiltration, the GAML model with its parameters did not have good performance by the c' index, which in 55% of the cases were considered as worse to bad (c'=0.5), overestimating Ti and I. The combinations using ψf calculated by the Risse s et al. (1995) equation also had performance by the c' index from worse to bad (c'=0.5) in all the trials, underestimating Ti and I during the whole time in both surface conditions. The combination (K0, θs and Cecílio s (2005) equation) showed the best results, with performance by the c' index in 66% of the cases considered as good or better (c'=0.66). The use of Tie values to represent hydraulic conductivity of the soil profile was proven a good alternative because the highest reliability in its determination.