China's food security is threatened by the unsustainable use of water resources in North and Northwest China

China has a growing population of 1.35 billion at the moment and has been largely self-sufficient in its food production. In consideration of the major agricultural resources (land, available fresh water, and ambient temperature), China is actually very vulnerable in maintaining its food security. Due to the unfavorable distributions of its water resources and temperature conditions, almost all the land that can be cropped has been utilized. Over cropping and over irrigation has led to some serious problems in two major areas of this country. In Northwest China where most of the land belongs to the inland river system, over expanding of irrigated area has resulted in some serious ecological problems, such as shrinking of oasis and desertification of grasslands. In North China Plain where about half of the country's wheat and maize are produced, over cropping has been supplemented with underground water for several decades, which has led to fast drop of underground water table, for example, 0.88 m per year in the recent 30 years at Luancheng County. China's food security is threatened by its diminishing and unsustainable use of water resources. Integrative agronomic, biological, engineering, and administrative practices that can sustainably use the water resources will be the key ways out to secure the country's future food production.