Uso e eficiência da água no perímetro irrigado de Poção da Ribeira em Itabaiana/SE

Abstract

The Water is one of the natural resources indispensable for the maintenance of the various forms of life on the planet. For ANA (2014) irrigation uses about 70% of the water withdrawn from the global system of rivers, lakes and underground springs. With this, irrigated agriculture nowadays is necessary to ensure the production of food. However, it’s necessary to evaluate and adapt each of the factors that compose the production system, including the efficiency of the use and management of irrigation water. In order to evaluate the irrigation system of the Poção da Ribeira irrigated perimeter of (PIPR) in 2016, located in the city of Itabaiana / SE, the present study has as general objective to determine the efficiency of water use application, besides the efficiency of its use of water, in twelve lots. Using the proposal described by Keller and Karmeli (1974) to evaluate the perimeter irrigation system, were determined the uniformity coefficients: of Christiansen (CUC), Emission (CUE), Absolute Uniformity (CUEa) and Static (Us). In order to determine the efficiency of application of the irrigation system, were determined the efficiencies: application (Ea), potential application (Epa), application to properly irrigated area (EDad) and irrigation to properly irrigated area (Eipad). To determine the water use, the meteorological data were obtained with the COHIDRO, and the reference evapotranspiration (ETo) was calculated by the standard Penman-Monteith method and crop evapotranspiration (ETc). Finally, in order to discover the real need of the crops, there was a comparison of the water depth applied by the farmers in the crops with ETc. The results of CUC, CUE, CUEa and Us were, respectively, 91.45%, 86.41%, 84.05% and 86.48%, values with parameters varying from good to excellent on the scale of Mantovani (2006). The Ea had an acceptable value for Bernardo (2006) of 82.09% and the EPA, EDad and Eipad were, respectively, 67,37%, 91,04% and 55,09%, values considered, with the exception EDad, considered unacceptable in literature for Keller e Bliesner (2000). The highest value of ETo was 5.4 mm day-1 and the lowest value was 3.1 mm day-1. The ETc had its highest value in 5.86 mm day-1 and the lowest in 1.44 mm day-1 . Compared with the applied water depth, it's evident the water deficit, between -1,61% and - 72,51%, in the most irrigations of the lots.