Efeitos de elementos meteorológicos na evapotranspiração estimada pelo Irrigâmetro nas condições climáticas da Zona da Mata mineira

• Ano de defesa: 2009
• Autor(a) principal: Caixeta, Samuel Petraccone
• Orientador(a): Oliveira, Rubens Alves de
• Banca de defesa: Tagliaferre, Cristiano , Reis, Edvaldo Fialho dos , Martinez, Mauro Aparecido
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Engenharia Agrícola
• Departamento: Construções rurais e ambiência; Energia na agricultura; Mecanização agrícola; Processamento de produ
• País: BR
• Palavras-chave em Português: Irrigação agrícola; Evapotranspiração; Radiação atmosférica
• Palavras-chave em Inglês: Irrigation; Evapotranspiration; Radiation
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA::ENGENHARIA DE AGUA E SOLO
• Link de acesso: http://locus.ufv.br/handle/123456789/3534

Quantifying the water consumption by major crops and the correct scheduling for its application are valuable issues to the irrigation management. It was developed at the Federal University of Viçosa an evapo-pluviometric equipment named Irrigâmetro, which allows measuring the evapotranspiration and the precipitation, providing the right time to irrigate, the running time for the irrigation system or its speed as well. The objectives of this research were: (a) to determine the coefficient of Irrigâmetro (KI) to the 2, 3, 4, 5 and 6 cm water depths in the evaporator, for 1, 3, 5 and 7 days intervals; (b) evaluate the performance of the Irrigâmetro estimating the reference evapotranspiration in the Zona da Mata's climate for the months analyzed, and (c) evaluate the interactions of the meteorological elements maximum temperature, minimum temperature, relative humidity, wind speed and radiation on the reference evapotranspiration estimated by the Irrigâmetro, operating with different depths of water in the evaporator and the Class A evaporation pan. The study was conducted at the Irrigâmetro Research and Development Unit, located in the Hydraulics, Irrigation and Drainage Experimental Area Agriculture Engineering Department, Viçosa-MG. The experiment was carried out in a completely randomized design with five treatments and three replications. The treatments consisted of Irrigâmetros equipped with evaporator operating with the following water depths: N2 = 2, N3 = 3, N4 = 4, N5= 5 and N6 = 6 cm, taken from the own equipment reference level, totaling 15 Irrigâmetros. The KI coefficient was obtained by the ratio between estimated crop evapotranspiration obtained by the Irrigâmetro and reference evapotranspiration obtained by the Penman-Monteith FAO 56 method. The analysis of the performance of the Irrigâmetro to estimate the reference evapotranspiration was made comparing the results with those obtained from the device to the equation Penman- Monteith FAO 56. The ranking of the evapotranspiration estimative was based on the values of the standard estimative error (SEE), coefficient of determination (r2) and the equation parameters (a and b) of the linear regressions. The best alternative was the one that had higher r2, lower SEE and b near to the unit. The accuracy was amended by the WILLMOT agreement index, represented by the letter "d", where the values range from zero for no agreement to 1 for perfect agreement. To evaluate the direct and indirect effects of each climatic component on the evapotranspiration estimated by the Irrigâmetro and by Class A evaporation pan, the path analysis was used, where evapotranspiration was the dependent variable and the climatic elements were the independent variables. The coefficient of Irrigâmetro increased with the increase of water level within the evaporator, for all time intervals. The Irrigâmetro showed a good performance to estimate the reference evapotranspiration in the climatic conditions of the Zona da Mata mineira when operated with the water depths in evaporator of 2 and 3 cm, with the best estimate at 2,36 cm. For the path analysis, at all studied water depths and in the Class A pan, the weather element that showed higher correlation with the evapotranspiration estimative was the radiation, followed by maximum temperature and relative humidity. The lowest correlations with the main variable were wind speed and minimum temperature, and both were not significant with 1% of probability by the t test. The indirect effect of the variable maximum temperature through radiation stood out as the most involved in trying to explain the evapotranspiration estimated by the Class A pan. The minimum temperature was the lowest correlation with the evapotranspiration obtained from the Class A evaporation pan, while the wind speed showed no significant correlation.