Quantifying uncertainty in agricultural water sustainability indicators for soybean and wheat crops

Accurate water usage assessments are crucial for effective water management in agriculture given the significant impact it has on Earth’s water resources and its inherent variability across different models. We evaluate the uncertainty in water usage indicators for soybean and wheat crops at both global and local levels. The assessment focuses primarily on the water footprint and the water debt repayment time, considering both their green and blue water components. Based on the results obtained from four global climate models available in the ISIMIP repository, a spatial and quantitative assessment is performed to evaluate the uncertainty associated with these indicators. We found a very high variability of blue water use in regions where crops tend to require irrigation for efficient growth. While the high variability in blue water footprint balances out around 8% on a global scale, it remains significantly influential at the country level with values reaching more than 50%. Water resources need to be well managed in order to distribute local water capital equitably between different uses. The findings of this study offer insights into the uncertainty of water usage indicators, empowering policymakers to make informed decisions regarding water management in their territory.