Water-scarcity footprints and water productivities indicate unsustainable wheat production in China

Abstract

Water shortage is a critical constraint limiting China’s capacity for food security. To provide evidence supporting environmentally sustainable water use in food production, this study compared irrigation water productivities (IWPs) and water-scarcity footprints (WSFs) for China’s wheat production at high spatial resolution. Contrary to previous water productivity studies assessing crop yield over total water consumption, it was found that IWPs in China’s water-scarce northern regions were much lower than those in water-rich southern regions. The WSFs further demonstrated the larger environmental impacts resulting from irrigation in water-scarce northern regions. Hotspot regions, having IWPs in the lowest tercile (<5.2 kg m−3) and WSFs in the highest tercile (>0.058 m3 H2Oe kg−1), were mainly located in the Huang-Huai-Hai and northwestern regions and accounted for 34% of the cropping area but 61% of irrigation water use. Historically, the south was also an important contributor of China’s wheat production, but progressive shifts toward highly resource-efficient cropping in the Huang-Huai-Hai region has occurred. The paradox is that gains in total crop water efficiency have led to increased irrigation demand and water scarcity. Today, croplands suitable for wheat production lie fallow in some southern regions in the winter. A national reassessment of this situation is urgently needed.