Impact of water productivity and irrigated area expansion on irrigation water consumption and food production in China in last four decades

Water shortage caused by irrigation has been widely concerned around the world. Despite the application of various water-saving technologies to improve irrigation efficiency and water productivity, irrigation water consumption is still high or even rising in some regions due to land expansion. Similarly, China has substantially increased the application of water saving technology in recent decades but water shortage are still remained. The aim of this research is to clarify how water productivity and irrigated area expansion have affected irrigation water consumption and food production using satellite-based evapotranspiration and gross primary productivity data over the past decades. The results clarify the significant contribution of irrigated area expansion to the increase of irrigation water consumption and highlight the importance of water productivity in slowing down the increase of irrigation water. Spatially, the contributions of the two factors are different in each sub-region. In Northeast China, 65.10 % of the increase in irrigation water was caused by irrigated area expansion, while 27.97 %, 17.31 % and 12.95 % respectively in the upper and middle reaches of the Yellow River, Xinjiang and Southwest China, resulting in a significant irrigation water increase in these four sub-regions. Contrarily, in Huang-Huai-Hai Plain, although land expanded by 23.5 %, irrigation water consumption increased only by 4.1 % due to 44.7 % of increase in irrigation water productivity. For the whole China, from 1982 to 2017, driven by the 44.5 % increase in national irrigation water productivity, irrigation water consumption only increased by 34.8 %, while gross primary productivity increased by 94.8 %. This study illustrates the crucial role of water-saving technology and irrigated area expansion played in ensuring China’s water and food security. It suggests that water saving and increasing water supply are equally important for China’s future agricultural water management.