Precipitation recycling of water used for irrigation in Central Brazil

About half of Brazil’s water demand is for irrigation, which has expanded greatly in Central Brazil in the last several decades. This study aims to estimate the feedback of irrigation on the regional climate system. More specifically, we estimate the amount of water withdrawals for irrigation in four irrigation zones in Central Brazil reprecipitate locally and in downwind regions. First, we used satellite data products to characterize the irrigation activity in four irrigation zones in Central Brazil during 2001–2018 and to estimate the water withdrawals from the rivers. Second, we used a reprecipitation dataset to estimate the fate of evapotranspiration from these irrigation areas. Then, we separated how much moisture recycling comes from rainfall and how much comes from irrigation. Finally, we calculated how much of the moisture was recycled locally and in downwind regions. Our results show an expansion of irrigation activity, with an increase in the number of center pivots, irrigation area, irrigation depth, and water used for irrigation. We also observed an increase in precipitation recycling over these years due to the presence of additional moisture in the atmosphere, with part of it falling in the same basin where irrigation occurred (about 4 %-8 %) and the other part flowing to other regions of the continent, mainly to the Paraná-Prata basin. On average, half of the water removed from Central Brazilian rivers for irrigation reprecipitates in South America. Our study demonstrates that, in addition to increasing crop production, irrigation can contribute to precipitation locally and in other parts of South America.