Drivers of water footprints in crop production across different temporal and spatial scales

The water footprint (WF) of crop production indicates the water consumption for crop growth in a specific area over a certain time, enabling comprehensive water use efficiency assessments to be achieved for different types of water. Improved spatial and temporal resolutions in quantification enable the water footprint (WF) in crop production to be a comprehensive indicator of water consumption in agricultural water management. However, in time, although daily and monthly blue (irrigation water) and green (rainfall) water resources are unevenly distributed in monsoon climate areas, the crop WF are generally recorded by years. In space, there is a lack of quantitative research on the effects of different spatial levels on the variation in crop WFs. Meanwhile, effect of developments in water-saving irrigation techniques on large-scale crop WF accounting is unclear yet.

We conducted a series of case studies for China in order to address above three issues. In the first selected case for maize and wheat production in the Baojixia Irrigation District (BID) of Shaanxi province in the west China, the WF of crop production was analysed based on a regional distributed hydrological model and the associated meteorological driving factors on daily, monthly, and yearly scales were identified (Gao et al., 2021). The latter two case studies focused on wheat across the whole mainland China based on gridded crop WF simulations over the period 2000-2014. The WFs of wheat production at five different spatial levels, including crop field, county, river sub-basin, provincial, and large river basin were mapped followed by an analysis of meteorological and human management factors (Mao et al., 2021). The differences in terms of magnitudes, composition, and benchmarks of wheat WF under furrow, sprinkler and micro irrigation methods as well as rain-fed conditions were further distinguished and identified (Wang et al., 2019). Results revealed non-negligible effects of temporal and spatial scales on crop WFs. The possibility and importance to account for developments of water-saving techniques in regional crop WF estimations are shown as well.

 

References

Gao, J., Xie, P., Zhuo, L., Shang, K., Ji, X., Wu, P. (2021) Water footprints of irrigated crop production and meteorological driving factors at multiple temporal scales. Agricultural Water Management, 255: 107014.

Mao, Y., Liu, Y., Zhuo, L., Wang, W., Li, M., Feng, B. (2021) Quantitative evaluation of spatial scale effects on regional water footprint in crop production. Resources, Conservation & Recycling, 173: 105709.

Wang, W., Zhuo, L., Li, M., Liu, Y., Wu, P. (2019) The effect of development in water-saving irrigation techniques on spatial-temporal variations in crop water footprint and benchmarking. Journal of Hydrology, 577: 123916.