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Evapotranspiration over crop growth period, also referred to as the consumptive water footprint of crop production (WFCP), is an essential component of the hydrological cycle. However, the existing high-resolution consumptive WFCP datasets do not distinguish between soil evaporation and crop transpiration and disregard the impacts of different irrigation practices. This restricts the practical implementation of existing WFCP datasets for precise crop water productivity assessments, agricultural water-saving evaluations, the development of sustainable irrigation techniques, cropping structure optimization, and crop-related interregional virtual water trade analysis. This study establishes a 5-arcmin gridded dataset of monthly green and blue WFCP, evaporation, transpiration, and associated unit WFCP benchmarks for 21 crops grown in China during 2000–2018. The data simulation was based on calibrated AquaCrop modelling under furrow-, sprinkler-, and micro-irrigated as well as rainfed conditions. Data quality was validated by comparing the current results with multiple public datasets and remote sensing products. The improved gridded WFCP dataset is available at 10.5281/zenodo.7756013 (Wang et al., 2023) and effectively compensated for the gaps in the existing datasets through (i) revealing the intensity, structure, and spatiotemporal evolution of both productive and non-productive blue and green water consumption on a monthly scale, and (ii) including crop-by-crop unit WFCP benchmarks according to climatic zones. [ABSTRACT FROM AUTHOR]

Adaptation to future climate change with limited water resources is a major global challenge to sustainable and sufficient crop production. However, the large-scale responses of the crop water footprint and its associated benchmarks under various irrigation regimes to future climate change scenarios remain unclear. The present study quantified the responses of the maize and wheat water footprint (WF) per unit yield (m 3 t -1) as well as the corresponding WF benchmarks under two Representative Concentration Pathway (RCP) scenarios, RCP2.6 and RCP8.5, in the 2030s, 2050s, and 2080s at a 5 arcmin grid level in China. The AquaCrop model with the outputs of six global climate models from Phase 5 of the Coupled Model Intercomparison Project (CMIP5) as its input data was used to simulate the WFs of maize and wheat. The differences among rain-fed wheat and maize and furrow-, micro-, and sprinkler-irrigated wheat and maize were identified. Compared with the baseline year (2013), the maize WF will increase under both RCP2.6 and RCP8.5 (by 17 % and 13 %, respectively) until the 2080s. The wheat WF will increase under RCP2.6 (by 12 % until the 2080s) and decrease (by 12 %) under RCP8.5 until the 2080s, with a higher increase in the wheat yield and a decrease in the wheat WF due to the higher CO 2 concentration in 2080s under RCP8.5. The WF will increase the most for rain-fed crops. Relative to rain-fed crops, micro-irrigation and sprinkler irrigation result in the smallest increases in the WF for maize and wheat, respectively. These water-saving management techniques will mitigate the negative impact of climate change more effectively. The WF benchmarks for maize and wheat in the humid zone (an approximate overall average of 680 m 3 t -1 for maize and 873 m 3 t -1 for wheat at the 20th percentile) are 13 %–32 % higher than those in the arid zone (which experiences an overall average of 601 m 3 t -1 for maize and 753 m 3 t -1 for wheat). The differences in the WF benchmarks among various irrigation regimes are more significant in the arid zone, where they can be as high as 57 % for the 20th percentile: WF benchmarks of 1020 m 3 t -1 for sprinkler-irrigated wheat and 648 m 3 t -1 for micro-irrigated wheat. Nevertheless, the WF benchmarks will not respond to climate changes as dramatically as the WF in the same area, especially in areas with limited agricultural development. The present study demonstrated that the observed different responses to climate change in terms of crop water consumption, water use efficiency, and WF benchmarks under different irrigation regimes cannot be ignored. It also lays the foundation for future investigations into the influences of irrigation methods, RCPs, and crop types on the WF and its benchmarks in response to climate change in all agricultural regions worldwide. [ABSTRACT FROM AUTHOR]

Adaptation to future climate change with limited water resources is a major global challenge to sustainable and sufficient crop production. However, the large-scale responses of crop water footprint and its associated benchmarks under various irrigation techniques to future climate change scenarios remain unclear. The present study quantified the responses of maize and wheat water footprint per unit yield (WFP, m³ t-1) and corresponding WFP benchmarks under two representative concentration pathways (RCPs) in the 2030s, 2050s, and 2080s at a 5-arc minute grid level in the case for China. The differences among rain-fed and furrow-, micro-, and sprinkler-irrigated wheat and maize were identified. Compared with the baseline year (2013), maize WFP will increase under both RCP2.6 and RCP8.5, by 17 % and 13 %, respectively, until the 2080s. Wheat WFP will increase under RCP2.6 (by 12 % until the 2080s), while decrease by 12 % under RCP8.5 until the 2080s. WFP will increase the most for rain-fed crops. Relative to rain-fed crops, micro irrigation and sprinkler irrigation result in the smallest increases in WFP for maize and wheat, respectively. These water-saving managements will more effectively mitigate the negative impact of climate change. Furthermore, the spatial distributions of WFP benchmarks will not change as dramatically as those of WFP. The present study demonstrated that the visible different responses to climate change in terms of crop water consumption, water use efficiency, and WFP benchmarks under different irrigation techniques must be addressed and monitored. It also lays the foundation for future investigations into the influences of irrigation methods, RCPs, and crop types on WFP and its benchmarks in response to climate change in all agricultural regions worldwide. [ABSTRACT FROM AUTHOR]

A core goal of sustainable agricultural water resources management is to implement a lower water footprint (WF), i.e. higher water productivity, and to maximize economic benefits in crop production. However, previous studies mostly focused on crop water productivity from a single physical perspective. Little attention is paid to synergies and trade-offs between water consumption and economic value creation of crop production. Distinguishing between blue and green water composition, grain and cash crops, and irrigation and rainfed production modes in China, this study calculates the production-based WF (PWF) and derives the economic value-based WF (EWF) of 14 major crops in 31 provinces for each year over 2001–2016. The synergy evaluation index (SI) of PWF and EWF is proposed to reveal the synergies and trade-offs of crop water productivity and its economic value from the WF perspective. Results show that both the PWF and EWF of most considered crops in China decreased with the increase in crop yield and prices. The high (low) values of both the PWF and EWF of grain crops tended to cluster obviously in space and there existed a huge difference between blue and green water in economic value creation. Moreover, the SI revealed a serious incongruity between PWFs and EWFs both in grain and cash crops. Negative SI values occurred mostly in north-west China for grain crops, and overall more often and with lower values for cash crops. Unreasonable regional planting structure and crop prices resulted in this incongruity, suggesting the need to promote regional coordinated development to adjust the planting structure according to local conditions and to regulate crop prices rationally. [ABSTRACT FROM AUTHOR]

With the quantitative accuracy of spatial and temporal scales being improved, water footprint(WF) of regional crop production is a suitable indicator to obtain comprehensiveunderstanding of water efficiency in agriculture. In water-deficient areas, water-savingagriculture is developing rapidly. However, to date, there is no study that explicitly addressesthe effect of water saving irrigation developments on large-scale WF accounting. Here, we fillthis gap for the first time through a case study of wheat in China over 2000-2014, duringwhich the cultivated area for micro-irrigation expanded 14 times. The green and blue WFs ofboth rain-fed and irrigated wheat are estimated using the AquaCrop model at a 5×5arc-minute resolution for each year. For irrigated wheat, we distinguish three irrigationtechniques: furrow, sprinkler and micro-irrigation. The WF benchmarks for each irrigationtype are further estimated separately for arid and humid zones. Results show thatthe annual contribution of the WF of wheat production under different irrigationtechniques in the overall decreasing national total (by 4.4%) changed significantly, inline with changes in harvested area over the study period. Irrigation accountedfor 70% of annual WF in China’s wheat land. Furrow irrigation dominated thenational total WF. The occupation by WF under micro-irrigation was the smallestbut jumped by 14 times in quantity whereas that under sprinkler halved. China’saverage WF per ton of wheat under sprinkler irrigation was 21% higher than thatunder micro-irrigation in 2014. The WF benchmarks of wheat in arid zones showsignificant sensitivities to irrigation techniques. The 20th percentile WF benchmarks ofwheat under micro-irrigation was 13% and 31% smaller than that under furrow andsprinkler irrigation, respectively, in arid zones. Meanwhile, the high provincialheterogeneities in terms of WF under varied distribution of irrigation techniqueswere also shown. The study provides possibility and shows importance to accountfor developments of water saving techniques in large scale crop WF estimations. [ABSTRACT FROM AUTHOR]