摘要:棉花是中亚重要的出口农产品之一，在水资源日趋严峻形势下，评价棉花生产需水和虚拟水贸易对区域水资源管理具有重要意义。本研究基于中亚175个站点长期气象数据，利用ArcGIS空间插值和作物系数法，结合棉花空间分布情况，首先估算了中亚五国的棉花需水量和单产需水量；基于单产需水量和国际粮农组织（FAO）的棉花产量和贸易数据，分析了1992年以来棉花的生产需水量、虚拟水贸易变化趋势及影响因素；最后评价了虚拟水贸易对中亚水资源的影响。研究结果表明：1）中亚棉花需水量为761.0~1033.9 mm，单产需水量为2834.4~5732.1 m3·t-1，其中产棉大国乌兹别克斯坦为4263.8 m3·t-1。2）1992-2017年，中亚地区棉花收获面积减少和产量偏低，导致总产量下降，生产需水量从初期的不足300亿m3下降到目前的不足200亿m3；棉花消费量增加导致出口量降低，净出口虚拟水量从初期的200亿m3左右下降到目前50亿m3；年均棉花生产需水量、净出口虚拟水量和净出口占生产需水量的比值分别为237.2亿m3、147.4亿m3和62.1%。3）1992-2017年，乌兹别克斯坦和土库曼斯坦通过棉花出口分别输出其可更新水资源总量的18.4%和12.7%，加剧了咸海流域水资源短缺。因此减少农田输水损失，提高棉花水分利用效率，是提升中亚棉花总产、减少棉花生产耗水、提升棉花出口贸易、减少虚拟水外输的有效措施。
关键词:棉花/
需水量/
单产需水量/
虚拟水贸易/
中亚五国
Abstract:Cotton is an important agricultural export item in Central Asia. Given the increasing shortage of water resources, it is necessary to evaluate the water requirements for cotton production and the virtual water trade of cotton for sustainable water resource management. In this study, the water requirements and specific water demands of cotton in the five countries of Central Asia were estimated from the long-term meteorological data from 175 stations using the ArcGIS spatial interpolation and crop coefficient method along with the distribution of cotton cultivation. Parameters for the specific water demands and the production and trade data from the Food and Agriculture Organization (FAO) as well as the amounts, change trends, and water requirements for production and virtual water trade of cotton in 1992-2017 were analyzed. Finally, the impact of virtual water trade on the water resources in Central Asia was evaluated. The results showed that: 1) the cotton water requirement was 761.0-1033.9 mm, the specific water demand was 2834.4-5732.1 m3·t-1, and the value of Uzbekistan cotton was 4263.8 m3·t-1, which was dominant in the calculations of water requirement for cotton production and the amount of exported virtual water of cotton. The parameters for the specific water demand were reliable for the spatial-weighted calculation processes. 2) From 1992 to 2017, the water requirement for cotton production and the net exported virtual water amount of cotton trended downward due to decreases in the total production and export amounts of cotton. The decrease in total cotton production resulted from a decline in harvested area, and low yields in some Central Asian areas directly led to decreased water demand for production (from > 30 billion m3 to > 20 billion m3). An increase in cotton consumption was the main reason for declining virtual water exports in Central Asia; the net exported virtual water volume dropped from 20 billion m3 to 5 billion m3. From 1992 to 2017, the annual water requirement for production, net exported virtual water, and the ratio of net exported amount to production amount of cotton were 23.72 billion m3, 14.74 billion m3, and 62.1%, respectively. At present, approximately one-third of the water requirement for cotton production is exported via virtual water trade despite falling cotton exports. 3) In Central Asia, 6.5% of the renewable water resources (not including water loss in farmlands and conveyance loss in irrigation events) was exported in the form of cotton exports in 1992-2017. In Uzbekistan and Turkmenistan, 18.4% and 12.7% of the renewable water resources were exported, respectively, which negatively impacted the regional water resources and induced water shortages.
Key words:Cotton/
Water requirement/
Specific water demand/
Virtual water trade/
Five countries in Central Asia
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