Determinação da eficiência de aplicação de água em sulcos nos perímetros irrigados do Estado da Paraíba.

Abstract

The main objective of this work was to evaluate the efficiency of water application in irrigation by furrows in Irrigated Perimeters of the State of Paraíba, administered by the National Department of Drought Control (DNOCS). In order to carry out the tests, three plots were selected in each perimeter, located in soils of soils most representative of each one of them. The choice of the grooves within the plots was made entirely at random.The evaluation of the efficiency of application was terminated by the ratio between the volumes of water stored in the plots In addition to evaluating the application efficiency of water in irrigation, for each plot, the yield curves and the infiltration equations were determined. The average efficiency of application of irrigation water was 40, 25, 51,10 and 54,96 percent for the Irrigated Permeters Engineer Arcoverde, São Gonçalo and Sume, respectively. The average efficiency for the three perimeters was 48.77 percent. The application efficiencies were affected by the uneven distribution of the water slides stored in the soil. This irregularity was revealed by determining the coefficients of variation of the same. The values ​​found were very high and varied between 22 and 200 percent. The fact of the unevenness in the water slides stored in the soil was due to the microtopography of the terrain being quite irregular, possibly as a consequence of the abatement of the landed parts, resulting from an inadequate systematization. This was shown by the coefficients of variation of the mean slopes of the plots. These coefficients will range from 47 to 172 percent. In the vast majority of the plots studied, the irrigations were restarted when the water content of the soil was still close to or even above the field capacity. This has done much to decrease the efficiency of water application. The inflow rates applied were quite different, within the same perimeter. In some cases, these were higher than the non-erosive maximum flows, theoretically calculated. In order to rationalize the irrigation management and increase the water application efficiency in the Irrigation Perimeters evaluated, it is recommended: Before irrigation, perform a proper systematization of the soil, in order to obtain grooves with uniform slopes with the objective of avoiding problems of unevenness in the distribution of the lamina of water stored in the soil. Properly schedule the irrigations of such as to avoid excessive application and consequent water loss.