Water resources transfers through Chinese interprovincial and foreign food trade
Water resources transfers through Chinese interprovincial and foreign food trade
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DOI：
10.1073/pnas.1404749111
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发表时间：
2014-07-08
影响因子：
11.1
通讯作者：
Rodriguez-Iturbe, Ignacio
中科院分区：
文献类型：
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作者：
Dalin, Carole;Hanasaki, Naota;Rodriguez-Iturbe, Ignacio
中国的水资源正面临着社会经济发展、饮食结构转变和气候变化带来的越来越大的压力。农业仍然集中了全国大部分取水量。此外，水和耕地可用性的空间不匹配——北方农业用地丰富而水资源匮乏——加剧了水资源短缺，并导致虚拟水通过农业贸易从干旱地区转移到湿润地区。我们使用一般均衡福利模型和线性规划优化来模拟中国的省际食品贸易。我们将这些贸易流向与省级商品虚拟水含量估算相结合，构建中国国内外虚拟水贸易网络。我们观察到各省之间农业用水效率存在很大差异。此外，一些省份特别依赖灌溉而不是雨水。我们分析虚拟水流模式和相应的节水量。我们发现这个省际网络连接度高，流量分布相对均匀。水流量的很大一部分来自国际进口（20%），其中以大豆（93%）为主。我们发现，中国的国内粮食贸易在雨水方面是有效的，但在灌溉方面是低效的，这意味着干旱、灌溉密集的省份往往会向湿润、灌溉密集度较低的省份出口。重要的是，当纳入外国进口时，中国的大豆贸易从一种低效的系统转变为一种节约水资源的特别高效的系统（每年节省灌溉水 20 km(3)，总计 41 km(3)/年）。最后，我们确定了在提高灌溉生产力方面表现出巨大潜力的特定省份（例如内蒙古）和产品（例如玉米）。
China's water resources are under increasing pressure from socioeconomic development, diet shifts, and climate change. Agriculture still concentrates most of the national water withdrawal. Moreover, a spatial mismatch in water and arable land availability-with abundant agricultural land and little water resources in the north-increases water scarcity and results in virtual water transfers from drier to wetter regions through agricultural trade. We use a general equilibrium welfare model and linear programming optimization to model interprovincial food trade in China. We combine these trade flows with province-level estimates of commodities' virtual water content to build China's domestic and foreign virtual water trade network. We observe large variations in agricultural water-use efficiency among provinces. In addition, some provinces particularly rely on irrigation vs. rainwater. We analyze the virtual water flow patterns and the corresponding water savings. We find that this interprovincial network is highly connected and the flow distribution is relatively homogeneous. A significant share of water flows is from international imports (20%), which are dominated by soy (93%). We find that China's domestic food trade is efficient in terms of rainwater but inefficient regarding irrigation, meaning that dry, irrigation-intensive provinces tend to export to wetter, less irrigation-intensive ones. Importantly, when incorporating foreign imports, China's soy trade switches from an inefficient system to a particularly efficient one for saving water resources (20 km(3)/y irrigation water savings, 41 km(3)/y total). Finally, we identify specific provinces (e. g., Inner Mongolia) and products (e. g., corn) that show high potential for irrigation productivity improvements.