Assessing the components of, and factors influencing, paddy rice water footprint in China

Water footprint (WF) can help understanding of how to grow more food with less water. The aim of this paper is to distinguish the factors influencing the paddy rice water footprint, by using path analysis of the WF, its composition and distribution over 30 provinces, municipalities and autonomous regions (hereafter, provinces) in China during 1996-2015. The results show that the annual national WF was approximately 190.74 G m(3), including 55.41 % green, 22.65 % blue and 21.94 % grey water respectively. WF basically remained stable over time. WF of the northeast increased from 16.70 G m(3) to 39.19 G m(3) during the observed period. WF for per unit paddy rice product (WFP) was 995.5 m(3)/t in the latest 20 years. Provinces with high WFP and blue water proportion were located in western China and the north China plain; all the low WFP values and blue water proportions were found south of the Yangtze River. The average temperature (ATE), irrigation water utilization coefficient (IWC) and fertilizer rate per sown area (FER) were the parameters closely and positively to WFP, both temporally and spatially.