Water scarcity effects of the expansion of sugarcane in the Parana basin in Brazil

Abstract

Biofuel is an important renewable fuel in the energy transition, especially in the transport sector. Bioethanol demand is rising, which means that the land use for biofuel crops such as sugarcane is increasing. Brazilian sugarcane-based bioethanol is a major source of biofuel. It is expected that Brazilian bioethanol production will increase, and thus sugarcane expansion is likely to occur, especially in the Parana basin in south east Brazil. Biofuel increase is associated with risks, such as food competition and increased water consumption. This thesis investigates what the impact of expansion scenarios would be on water scarcity by the year 2030. Land use projections for 2030 are adapted for use in the hydrological model PCR-GLOBWB, which is run over a period of 30 years in various scenarios. These are analyzed based on discharge and sampling points, which are reported chronologically, seasonally, and in flow duration curves. Water scarcity is analyzed based on river flow reduction. According to the findings, tenfold expansion of non-irrigated Brazilian sugarcane will not result in water scarcity in the Parana basin. When irrigation is fully applied however, a doubling of sugarcane production just touches the low water scarcity border (>20% flow reduction), a tripling causes low water scarcity (20-30%), a fivefold increase results in moderate water scarcity (3040%) and a tenfold increase leads to severe water scarcity (>40%). This indicates that for water scarcity projections, the irrigated area is more important than the expanded area. From a perspective of avoiding water scarcity, it is better for policies to focus on limiting irrigation than on limiting sugarcane expansion. For the near future, the likely expansion within Parana for the year 2030 is expected to double or (optimistically) triple. With irrigation remaining low (25% across Brazil, including the dry north east), these expansions will likely cause low to no water scarcity. This allows for a doubling or even tripling of current bioethanol production. Although it remains important to assess water scarcity, it will likely not be the main limitation to bioethanol expansion.