Understanding Complexities in Sustainable Irrigation Water Withdrawals: Global Impacts on Food Production and Land Use
Population, income, and bioenergy growth will increase unrenewable water use for agriculture. Pursuing sustainable irrigation—targeting future water security—cannot be done in isolation because of its interactions with other sustainable development goals. Researchers from Purdue University and University of New Hampshire, under a Cooperative Agreement led by Stanford University, explored tradeoffs within this water, food, and energy nexus. Scientists found that restricting unsustainable water use for irrigation in the absence of significant efficiency gains could negatively impact global food security and terrestrial carbon emissions.
This analysis of sustainable irrigation highlights the potentially unanticipated consequences of larger-scale adaptation measures. The multi-scale modeling approach developed in this study helps identify the fine-scale, heterogeneous local responses to macro-level shocks, as well as the aggregated feedback to the system. This method permits us to deepen the understanding of the complex interconnection between water, land, food, energy and climate, and can facilitate more effective decision-making.
A grid-resolving partial equilibrium economic model is developed and coupled with a fine-scale hydrological model to assess the extent of unsustainable irrigation at the sub-basin level. Using this integrated modeling framework, researchers simulated the outcomes of eliminating unsustainable irrigation under a variety of scenarios that interact agricultural productivity growth with adaptations to move physical and virtual water. The study shows that without significant simultaneous improvements in the productivity of irrigation water, it could cause a rise in food prices and additional cropland expansion. This in turn would lead to a further 800 thousand undernourished people, and an additional 0.87 gigatons of carbon emissions.