## 3 Results and Discussion
### Virtual Water Trade in Gansu Province from 2007 to 2012  
#### 3.2.1 Spatial Patterns of Virtual Water Flow in and around Gansu Province  
Patterns of virtual water supply and demand between Gansu province and other regions are important to consider. The results of the current study show that, in comparison with 2007, the use of locally produced virtual water in Gansu decreased by 2.262 billion m\({}^{3}\) in 2010 (Table 2). According to the Gansu Provincial Water Resources Bulletin in 2007 and 2010, in 2010 the water-saving irrigated area reached 3 million mu (1/15 ha) more than that in 2007. In 2012, the total amount of virtual water contained in products was 41.259 billion m\({}^{3}\), and 32.593 billion m\({}^{3}\) of virtual water was provided for local use, accounting for 79.00% of the total. On the basis of 2007 and 2010 statistics, the use of locally produced virtual water increased by 50.72 and 7.334 billion m\({}^{3}\), respectively in 2012 (Table 2); this is related to the increase in virtual water consumption across all three industry categories. The proportion of virtual water employed locally verses total virtual water decreased annually from 94.8%, 89.52% to 81.43%, while exports have been mounting, from 5.2%, 10.48%, to 18.57% (Table 3). This trend suggests that the increase in total virtual water may be due to a rise in the import of products with high virtual water content, rather than to the decline of virtual water exports. The industries with the highest direct water use are the dominant exporters, such as those in the primary industry category (Table 4). Therefore, Gansu should focus on improving water use efficiency and minimizing the development of industries with high direct water use to alleviate the pressure on water resources.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{2}{c}{**2007**} & \multicolumn{2}{c}{**2010**} & \multicolumn{2}{c}{**2012**} \\ \cline{2-6}  & **Output** & **Input** & **Output** & **Input** & **Output** & **Input** \\ \hline Primary Industry & 14.62 & 1.11 & 28.62 & 1.11 & 72.15 & 1.61 \\ Secondary Industry & 0.32 & 12.94 & 0.70 & 19.68 & 1.67 & 57.40 \\ Tertiary Industry & 0.16 & 2.09 & 0.26 & 3.73 & 0.49 & 27.65 \\ Total & 15.10 & 16.14 & 29.58 & 24.52 & 74.31 & 86.66 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Export of virtual water from Gansu and import of virtual water into Gansu across primary, secondary, and tertiary industries.  
Figure 3: Comparison of the total water production and virtual water consumption in Gansu province from 2007 to 2012.  
Between 2007 and 2012, virtual water in Gansu mainly flowed towards developed coastal cities (Figure 4) such as Beijing, Shanghai, Guangdong and Tianjin. This is partially due to the encouragement of advances and reforms in emerging and traditional industries, and the implementation of virtual water strategies in these centers [70; 71]. Over 80 million m\({}^{3}\) of virtual water flowed to the provinces of Jiangsu, Zhejiang and Hebei in 2007, 2010, and 2012, respectively. Gansu, as a water-scarce province, consistently exported large volumes of virtual water to water-rich areas from 2007 to 2012. Such a trade pattern no doubt increases the pressure on water resources and affects economic development in Gansu [72; 73]. The spatial pattern of virtual water trade in Gansu province was developed by ranking the output volume of virtual water flowing from Gansu to different export regions. The export area included China's eastern coast along with the central, western, and northeast regions. Virtual water output volume was divided into three ranges: less than 80 million m\({}^{3}\), 40 million to 80 million m\({}^{3}\), and higher than 40 million m\({}^{3}\).  
Figure 4: \(Cont\).