China's rapid socioeconomic growth continues to tax national water resources - especially in the agricultural sector - due to increasing demands for food. And, because of the country's climate and geography, irrigation is now widespread, burdening rivers and groundwater supplies.

One solution to these growing problems, however, might be to reorganize the country's crop production and trade, especially in agricultural provinces such as Inner Mongolia, Heilongjiang and Hebei, according to new report issued by Princeton University's Woodrow Wilson School of Public and International Affairs and School of Engineering and Applied Science and scientists in China and Japan.

The researchers report in the journal Proceedings of the National Academy of Sciences that reducing agricultural production in these provinces and importing food commodities from other provinces or nations instead could help China conserve more water. These provinces all use large volumes of water to produce crops that are later exported to wetter regions. If balanced with more water-efficient irrigation systems locally, restructuring these regions could reduce national water use while avoiding an excessive geographically centralized agricultural production.

"Our analysis provides a framework for understanding how such policies would benefit China's water use in the future," said study co-author Denise Mauzerall, professor of environmental engineering and international affairs. In particular, corn production and trade at the domestic level might be an area to target as changes could significantly reduce national water use for irrigation."

"Overall, China may want to consider a targeted investment in agricultural research and development," said lead author Carole Dalin, a Princeton University Ph.D. student studying environmental engineering.

Of China's industries, agriculture is the most water-intensive in terms of production and covers most of the country's northern provinces. Crops like corn, rice and wheat thrive best in these drier regions, but rainfall is limited, and stores of underground water are diminishing. To fulfill high production demands, water is drawn from underground reservoirs (aquifers) in the northern provinces and used for irrigation more rapidly than it is replenished.