Impacto das mudanças climáticas na demanda de água para irrigação da cana-de-açúcar na Bacia Hidrográfica do Rio Gramame-PB

Abstract

Nowadays, climate change is a more frequently discussed topic, because the impacts that they produce on water resources can be felt more intensively in recent years, and these impacts are directly reflect on humans and their activities. Therefore, projecting climate change will allow us to understand how climate variables will behave over the years. These projections are important because the mitigating measures taken by the government are based on them, and will also alert the population. The objective of this work is to analyze the impacts produced by the climatic changes on the demands of water for irrigation of sugarcane in the hydrographic basin of Gramame river. First, the changes in the temperature were evaluated, since it is fundamental in the calculation of evapotranspiration, then, the water demands were calculated. The Thornthwaite method was chosen to carry out the estimates of reference evapotranspiration, and based on these values, the evapotranspiration of all sugarcane cultivation that is distributed in the hydrographic basin was calculated and it was possible to determine the amount of water needed by the crop to survive, and how the demand for irrigation water has been affected by climate change. To observe the impact of changes in temperature, two scenarios proposed by the IPCC (Intergovernmental Panel on Climate Change) were used. These were: the RCP 4.5 (stabilization scenario), the RCP 8.5 (most pessimistic scenario), and three Regional Circulation Models (RCMs). These three are: the ICHEC-EC-EARTH-RCA4, MPI-ESM-LR-RCA4 and MPI-ESM-LR-REMO20. The study was also divided into three time periods, 2006-2037, 2038-2069, 2070-2100. From the results found, the model MPI-ESM-LR-REMO2009 best represented the current climate. The models projected average increases of 0.04 ° C in the first period of time, 0.48 ° C in the second period of time and 0.97 ° C in the third period of time. Finally, the demand for water for irrigation shows little growth when we look at the near future with the increase in temperature caused by climate change. When we deal with a more distant future, the increase in temperature can be felt with greater intensity. Na example of this, is the city of João Pessoa the models projected average demand increases of 423 m³ per year in the first period of time, 5,658 m³ per year in the second and 15,674m³ per year in the third.