Evaluation of water footprint in sugar industries and bioethanol distilleries in two different water basins toward water sustainability

Sugarcane farming and bioethanol production are water-intensive activities that result in high water competition. The competition, in turn, can exacerbate water scarcity. Therefore, this study aims to evaluate the water footprint (WF) of the sugar and bioethanol production at the Finchaa and Metehara sugarcane farms, which are located in different river basins in Ethiopia. The climatic data (minimal and maximum temperature, relative humidity, wind speed, and sunshine duration), meteorological data (rainfall), CROPWAT 8.0 model, nitrogen fertilizer application rates, sugarcane yield, and sugar and bioethanol production over 12 years (2008–2019) were used. Penman–Monteith method-based sugarcane water requirements of Finchaa and Metehara were found to be 2021.1 and 3605.4 mm/growing period, respectively. The sugarcane WF of Finchaa was 188.01 m(3)/t, which was composed of green (67.45 m(3)/t), blue (113.42 m(3)/t), and grey (7.14 m(3)/t) components, whereas the WF of Metehara was 239.11 m(3)/t consisting of green (29.42 m(3)/t), blue (204.13 m(3)/t), and grey (5.56 m(3)/t). The low sugarcane WF recorded was attributed to the high yield of sugarcane that was harvested in the study areas. Hence, the irrigation (blue WF) requirement is the major concern of water management in the basins. Similarly, the WF of bioethanol at the Finchaa distillery (2067.62 L/L) was much higher than that of the Metehara distillery (1441.54 L/L). However, both WFs were within the global range. Significant differences were observed between the two water basins. The sugarcane estate farm and bioethanol production processes require water management intervention to reduce the impact of WF in the basins.