Carole Dalin, Huanguang Qiu, Naota Hanasaki, Denise L. Mauzerall, and Ignacio Rodriguez-Iturbe

ENVIRONMENTAL SCIENCES

Significance

Agriculture represents the largest water-consuming sector in China, while industry and cities are growing competitors. To sustain a rapidly increasing population with richer diets, high levels of food production have come at significant environmental costs, such as groundwater overdraft and soil degradation. As socioeconomic growth and the associated pressure on water resources continue to increase, it is crucial to evaluate the effects of water-saving measures on agriculture, food trade, and water resources. This article estimates China’s future food trade patterns and associated water transfers and quantifies the effects of targeted irrigated land reductions on water consumption and food self-sufficiency, accounting for production displacement and local water productivity. Our findings provide important insights to policy-makers on trade-offs between environmental and agricultural objectives.

Abstract

China’s economic growth is expected to continue into the next decades, accompanied by sustained urbanization and industrialization. The associated increase in demand for land, water resources, and rich foods will deepen the challenge of sustainably feeding the population and balancing agricultural and environmental policies. We combine a hydrologic model with an economic model to project China’s future food trade patterns and embedded water resources by 2030 and to analyze the effects of targeted irrigation reductions on this system, notably on national agricultural water consumption and food self-sufficiency. We simulate interprovincial and international food trade with a general equilibrium welfare model and a linear programming optimization, and we obtain province-level estimates of commodities’ virtual water content with a hydrologic model. We find that reducing irrigated land in regions highly dependent on scarce river flow and nonrenewable groundwater resources, such as Inner Mongolia and the greater Beijing area, can improve the efficiency of agriculture and trade regarding water resources. It can also avoid significant consumption of irrigation water across China (up to 14.8 km³/y, reduction by 14%), while incurring relatively small decreases in national food self-sufficiency (e.g., by 3% for wheat). Other researchers found that a national, rather than local, water policy would have similar effects on food production but would only reduce irrigation water consumption by 5%.

See: http://www.pnas.org/content/112/15/4588.abstract.html?etoc

PNAS April 14, 2015 vol. 112 no. 15 4588-4593

Fig. 1.

VWT between Chinese provinces and the ROW (A, 445 km³) and trade-induced losses of blue water—from rivers, reservoirs, and aquifers—(B, 16.9 km³) in 2030 under the BL scenario. Numbers indicate the volume of water in cubic kilometers, and the link color corresponds to the exporting province. The map at the lower right provides a key to the color scheme. Note that China’s international imports account for 30% of all VWT. Inner Mongolia exports induce the largest blue water losses across provinces (6.4 km³). These graphics are created using a network visualization software (44).