Effects of sugarcane expansion on surface runoff and evapotranspiration in the Rio Grande basin

Abstract: The demand for sugarcane has increased in recent years as more countries desire to reduce its dependence of fossil fuels. Therefore, the number of sugarcane plantations has rapidly increased in Brazil which raises concerns for what effect these conversion of original land to sugarcane plantations have on local hydrology and climate. In this thesis, the effects of sugarcane expansion on surface runoff and evapotranspiration in the Rio Grande basin, Brazil were evaluated. Rio Grande basin is an area of great importance for the country in terms of hydropower generation and sugarcane cultivation. For the numerical experiments carried out in this thesis, several sugarcane scenarios were generated based on topographic features and mapping of areas suitable for growing sugarcane made by the Brazilian Institute for Agricultural Research (EBRAPA). A distributed hydrological model was used to estimate surface runoff and evapotranspiration rates in the river basin. Surface runoff and evapotranspiration rates were compared to a control scenario that corresponded to land use observed before sugarcane expansion. Results from simulations implied a reduction of 10.8% in surface runoff and an increase in evapotranspiration rate by 9.0% for the most severe scenario, which occurred at the Funil hydropower plant.