Ciência e Agrotecnologia (Feb 2009)
Parâmetros de desempenho de dezesseis equipamentos de irrigação por pivô central Parameters of performance of sixteen center-pivot irrigation equipments
Abstract
O tempo de uso de sistemas de irrigação por pivô central pode resultar em alteração de suas características hidráulicas, necessitando de avaliações periódicas para manter a uniformidade de distribuição de água em níveis aceitáveis. Objetivou-se, neste trabalho, avaliar as condições de funcionamento e desempenho de dezesseis pivôs centrais, localizados em onze municípios de Goiás e no Distrito Federal. Estimou-se o coeficiente de uniformidade de Heermann & Hein - CUH e uniformidade de distribuição - CUD, variação da lâmina coletada em relação à projetada e os fatores que interferem no desempenho dos equipamentos. Dos pivôs avaliados, quatro (25%) apresentaram CUH inadequado (The time of use of the center-pivot irrigation system may result in alteration of the hydraulic characteristics, frequent evaluations being needed to maintain the efficiency of water distribution at acceptable levels. The aim of this work was to evaluate the conditions of the use and the performance of sixteen center pivots, located in eleven municipal districts of Goiás State and Federal District, Brazil. The Heermann & Hein - CUH coefficient of uniformity and coefficient of distribution - CUD, variation between the collected and projected depth and verification of the main factors that influenced the performance were evaluated. Among the evaluated pivots, four (25%) presented inadequate CUH (< 80%) and three (18.75%) presented inadequate CUD (< 70%). The average depth applied was higher than the projected in three and lower in thirteen pivots, with the difference higher than 10% in only one pivot. Most of the evaluated pivots need maintenance to solve the following problems: emitters with flow rate different from the flow considered appropriate for some intervals of the equipments; emitters totally or partially clogged or damaged; absence of suspension strings; damaged pressure regulators; leaks in several points and speed displacement different from the observed on the relay percentile.
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