『Abstract
An accurate estimate of global water uses with high spatial resolution
is a key to assessing global water scarcity and to understanding
human's interference with the ecosystems. In spite of the progress
made previously, there is a lack of spatially explicit assessment
of both green and blue water uses in agriculture. In this paper,
we estimated consumptive water use (CWU) in cropland on a global
scale with a spatial resolution of 30 arc-minutes. A GIS-based
version of the EPIC model, GEPIC, is used for the estimation.
The results show that in crop growing periods, global CWU was
5938 km3 a-1 in cropland around the year
2000, of which green water contributed to 84％. On an annual basis,
global CWU was 7323 km3 a-1 in cropland,
of which green water contributed to 87％. We compared the simulated
consumptive blue water use (CBWU) with the statistical CBWU at
the national level among individual countries, and at the federal
state or province level in the USA and China. The comparison indicates
a good agreement between the simulated and statistical CBWU, suggesting
a satisfactory performance of the GEPIC model and reliability
of the estimation in irrigated cropland. The importance of green
water in both crop production and food trade calls for a better
management of green water, in addition to blue water.
Keywords: Water scarcity; Consumptive water use; Virtual water;
EPIC; GEPIC; Green water』
Introduction
Methods and data
The GEPIC model
Consumptive water use (CWU)
Calculation of consumptive green and blue water uses
High-resolution data of harvested area
Other data sets
Results and discussion
Consumptive water use (CWU)
Spatial pattern
Country-specific CWU in crop growing periods
Consumptive blue water use (CBWU)
Spatial pattern
Comparison between simulated and statistical CBWU at the national
level
Comparison between simulated and statistical CBWU in the USA
Comparison between simulated and statistical CBWU in China
Consumptive water use vs. virtual water trade at the national
level on a per capita basis
Improvement of crop water productivity (CWP) by better water
and nutrient management
Conclusion
Acknowledgements
Appendix A. Supplementary data
References