Adequação da capacidade de aplicação de água para sistemas de irrigação no Brasil

Abstract

Irrigation plays a vital role in the global context, both in terms of food production and the sustainability of water resources. In Brazil, this scenario is equally relevant due to the country's vast territorial extension and its remarkable climatic diversity, making the practice of irrigated agriculture essential to achieve desirable levels of productivity. In view of this, the adequate design and dimensioning of irrigation systems assume significant importance, since well-designed projects provide superior results. The present study was designed with the purpose of developing evapotranspiration correction factors to cover the entire Brazilian territory, based on maximum totals of 3, 5, 7 and 10 days. To calculate evapotranspiration, data from 380 meteorological stations distributed throughout the country were obtained from the National Institute of Meteorology. Due to the scope of the Brazilian territory and the great interference of climate change in recent years, the period from January 2011 to December 2021 was adopted for conducting the study. Subsequently, the Penman-Monteith equation (FAO-56) was applied to calculate evapotranspiration. Moving averages were then calculated for the desired critical intervals. Using the Simple Kriging technique, interpolated maps were generated that provided evapotranspiration correction factors for the entire Brazilian territory. It was observed that the use of daily data from the monthly average underestimates the evapotranspiration values for critical intervals. When comparing the monthly average and the 7-day critical interval, correction factors ranging from 1.04 to 1.35 were found. This represents a 4% to 35% reduction in the amount of water to be supplied by an irrigation system, which may result in losses in agricultural productivity. The use of adequate evapotranspiration values can directly influence the proper management of water resources, since it improves the accuracy of the preparation and execution of irrigation projects.