Hydrologic impacts of biofuel expansion in the Ivinhema basin, Brazil
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Brazil produces approximately a quarter of the world's yearly ethanol demand, making it a global leader in biofuel production. The repercussions for local water resources in areas of intensive biofuel expansion, however, remain uncertain. The purpose of this study is to assess the effects of various land-use scenarios on water sustainability in Brazil, specifically the Ivinhema basin. This basin, located in Southern Mato Grosso do Sul, has experienced extensive sugarcane expansion since the mid-1990s – a trend that is expected to continue in the short to medium term. To achieve the goals of the study, I used the Stockholm Environment Institutes' Water Evaluation and Planning software (WEAP), specifically, the Soil Moisture Method, to model hydrologic processes in the Ivinhema basin from 1990-2013. The study has two parts. The first part focuses on model calibration in a data poor environment. To circumvent poor data quality, I examined the effects on model accuracy of a number data processing methods for land-use, precipitation, and ethanol production data. A total of 8 different calibration scenarios were run using these different data inputs, which I evaluated for accuracy using Nash-Sutcliffe Model Efficiency coefficients. Those producing the best results were used as a baseline for part two. The second part of the study uses the baseline model developed in part one to investigate the crop yield and stream flow effects under three different irrigation and ethanol production scenarios. Water consumption for the ethanol production process has little impact on stream flows, with daily demand peaking at 0.7 percent of baseline flows. Irrigation, however, massively reduces flows -- when irrigation is limited to only sugarcane, flow reductions of over 60 percent only occurs on 1.98 percent of days, while reductions of up to 100 percent during the dry season. Despite these large flow reductions, sugarcane yield increase from irrigation was only 7-14 percent over the study period.