Human activities are increasingly leading to overuse of surface water and
nonrenewable groundwater, challenging the capacity of water resources to
ensure food security and continuous growth of the economy. Adaptation
policies targeting specifically water security can easily overlook its
interaction with other sustainability metrics and unanticipated local
responses to the larger-scale policy interventions. Using a recently
developed global partial equilibrium, grid-resolving model, nick-named
SIMPLE-on-a-Grid and coupling it with the global Water Balance Model, we
simulate the impacts of reducing unsustainable irrigation water
withdrawals on land use change and food supply, under a variety of future
(2050) scenarios with and without adaptations. Comparisons are made among
three policy interventions: inter-basin water transfers, investments in
agricultural productivity-enhancing technologies, and the promotion of
virtual water trade. Although each of these scenarios affects regional
food supply in a similar fashion, their implications for land cover
change, carbon emissions and global food security are quite different. By
allowing for a systematic comparison of these alternative adaptations to
future scarcity, the global gridded modeling approach offers unique
insights into the multiscale nature of the water scarcity challenge.
