Identificação de desuniformidade de aplicação em pivô central com a utilização de sensoriamento remoto

Abstract

Among the existing irrigation systems nowadays, the center pivot system has gained prominence due to its irrigated area capacity and potential of uniform distribution. Conversely, disuniformity of water distribution effect crop yield, and may have areas with deficit or excess of humidity. In this context, the objective of this study was to detect application disuniformity in center pivot with the aid of the remote sensing in the region of Cachoeira do Sul - RS. The monitoring was carried out using multispectral images on the Sentinel-2 satellite platform, acquired in the Semi-Automatic Classification Plugin (SCP) of the Qgis application. The images used to determine the normalized difference vegetation index (NDVI) were obtained for the growing seasons from October to April, for 2018 to 2022. Due to a restriction imposed to cloud covering in the scene, or NDVI saturation, only five images were obtained for all the analyzed years. From these images, it was possible to detect application disuniformity along the center pivot’s lateral line, forming circumferences of excess or deficit of application, resulting in different values of NDVI on the irrigated area. To confirm possible problems related to the machine, a field investigation was carried out to map nozzles and valves on the entire center pivot. It was verified nozzles with a bigger diameter than the recommended value, according to the nozzle mapping. Thus, the bands with excess of application in the period were a result of excessive flow rates from these nozzles. Therefore, the remote sensing was effective to indicate disuniformity in the center pivot, even presenting limitations such as NDVI saturation in final phenological phases of the crop.