Abstract
Balancing groundwater supply and food production is challenging, especially in large regions where there is often insufficient information on the groundwater budget, such as in the North China Plain (NCP) and the Northeast China Plain (NECP), which are major food producing areas in China. This study aimed to understand this process in a simple but efficient way by using Gravity Recovery and Climate Experiment (GRACE) data, and it focused on historical and projected groundwater storage (GWS) changes in response to changes in grain-sown areas. The results showed that during 2003–2016, the GWS was depleted in the NCP at a rate of −17.2 ± 0.8 mm/yr despite a decrease in groundwater abstraction along with an increase in food production and a stable sown area, while in the NECP, the GWS increased by 2.3 ± 0.7 mm/yr and the groundwater abstraction, food production and the sown area also increased. The scenario simulation using GRACE-derived GWS anomalies during 2003–2016 as the baseline showed that the GWS changes in the NCP can be balanced (i.e., no decreasing trend in storage) by reducing the area of winter wheat and maize by 1.31 × 106 ha and 3.21 × 106 ha, respectively, or by reducing both by 0.93 × 106 ha. In the NECP, the groundwater can sustain an additional area of 0.62 × 106 ha of maize without a decrease in storage. The results also revealed that the current groundwater management policies cannot facilitate the recovery of the GWS in the NCP unless the sown ratio of drought-resistance wheat is increased from 90% to 95%. This study highlights the effectiveness of using GRACE to understanding the nexus between groundwater supply and food production at large scales.
Highlights
Water shortages and food security are important issues in the world
The results show that (1) the long-term trend in the GWSA estimated based on Gravity Recovery and Climate Experiment (GRACE) is similar to that of the in situ GWSA, (2) in the North China Plain (NCP), the correlation between the GRACE-derived and in situ GWSA is relatively good (r = 0.83), which indicates that the GRACE inversion results are reliable, and (3) in the Northeast China Plain (NECP), the annual phases of the GRACE-derived and in situ GWSA are inconsistent and the correlation is poor (r = 0.22), which may be because the surface water storage changes in the rivers, lakes and wetlands are not well considered when subtracting the surface water storage anomalies (SWSA) from GRACE TWSA
We provided a case study to understand the historical and projected groundwater storage (GWS) changes at the large scale by using GRACE data, with a focus on the cause-effect relationship between agricultural water demand and the trend of GWS in two major food producing areas of China, i.e., the NCP and NECP
Summary
Water shortages and food security are important issues in the world. As the largest source of freshwater, groundwater is critically important for irrigated agriculture, and for global food security [1]. As irrigated agriculture constitutes approximately 40% of global food production [2], increased groundwater abstraction for irrigation has contributed substantially to the expansion in the global food supply [3]. This process has led to groundwater depletion in many parts of the world, such as northwestern India, the North China Plain (NCP), and the central United States and California [4]. From 1998 to 2010, the sown area of winter wheat in the Hebei Plain decreased by 49.62 × 104 ha, and 15.96 × 108 m3 of irrigation water was saved [13]. Zhang et al found that significant improvements in WUE have increased the crop yield in the NCP by 50% in the past 20 years [16]
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