Water demand management through price and market mechanisms is crucial for agricultural water management. However, how to set an appropriate agricultural water price remains unclear due to the uncertainty regarding the response of water demand to price changes and the complexity of the hydro-economic system. Thus, this study developed a water-economic model to examine both issues in the Heihe River Basin. The empirical results revealed that the basin’s agricultural water is currently price-inelastic, with a value of −0.26, but that at 0.27 yuan/m³, elasticity is gained. At this tipping point, water demand and economic output decline by up to 10.2% and 1.6%, respectively, while water productivity increases by 7.2%. It is noteworthy that the reallocation of water and land resources from agricultural sectors to non-agricultural sectors facilitated by a water price change is the main contributor towards water productivity improvement. This signifies the importance of managing water and land resources in an integrated framework to improve water productivity in the future. Our study contributes to the literature by suggesting that future policies for water-demand management should consider pricing that encourages water saving and the reallocation of water resources to high-value uses in order to increase water productivity.

The COVID-19 pandemic and the outbreak of the locust plague in Pakistan have severely impacted grain production and trade in South Asia, thereby posing serious threats to global grain security. This study formulated a comprehensive analysis of crop yield and trade restrictions consequent to the combined impact of COVID-19 and the locust plague with the GTAP model and quantitatively simulated the characteristics and mechanisms of changes in the production and trade patterns of major grain crops (paddy rice and wheat) in South Asia. Results indicate that COVID-19 and the locust plague affected global grain production and imports and exports to varying degrees. Grain production was reduced by 15% and global trade shrank sharply, with total imports and exports shrinking by 5.79% and 1.41%, respectively. This also led to international food prices changing significantly, which further influenced the food affordability and accessibility, especially for developing countries that are heavily dependent on imports. Nepal, Sri Lanka, and Bangladesh were the regions that experienced the highest rises in grain import prices, which caused the processed rice imports of Sri Lanka, Nepal, Bhutan and Maldives, and Bangladesh to drop by 81%, 77%, 80%, and 89%, respectively. Furthermore, the global grain trade patterns were also severely affected. South Asian countries’ grain trade links with China, Europe, Africa, and Latin America were weakened. Grain exports mainly converged in Africa, with Australia, the United States, and Latin America being the main exporters. The findings of this paper are helpful to identify countries facing high grain security risks and can shed light on policy measures to address the dual challenge for guaranteeing global grain security in the post-epidemic era.