武威绿洲农业开发对民勤绿洲来水量的影响——基于水足迹的视角

基于历史观测数据统计分析了1956年-2003年石羊河上游天然来水量与下游民勤绿洲来水量变化趋势,采用生产法计算了1950年-2006年武威绿洲农业水足迹,定量揭示了石羊河中游武威绿洲农业开发对区域水资源的真实占用及其对下游民勤绿洲来水量的影响。研究结果表明:①由于石羊河中游武威绿洲人类活动加剧,下游民勤绿洲来水量呈减少趋势;②中游武威绿洲农业水足迹呈快速上升趋势,粮食作物水足迹占最大比重;③中游武威绿洲农业水足迹与下游民勤绿洲来水量呈显著负相关关系,中游农业水足迹每提高1×108m3,下游来水量将减少0.2543×108m3;中游粮食作物水足迹每提高1×108m3,下游来水量将减少0.5021×108m3,中游武威绿洲农业开发是下游民勤绿洲来水量减少的最重要人文活动,粮食作物种植规模的扩大对下游来水量的影响很大;④通过控制农业生产规模,调整农业内部结构,降低单位农产品的虚拟水量,进而控制中游武威绿洲农业水足迹增长趋势是缓解下游民勤绿洲生态恶化的重要手段。

Impacts of Agricultural Development in the Wuwei Oasis on Water Resources in the Minqin Oasis in the Lower Reaches :Based on Water Footprint

The authors introduced a concept of water footprint and performed an integrative calculation of the real water occupation for agricultural development in the Wuwei oasis in the middle reaches of the Shiyang River basin. We comprehensively analyzed the impacts of the agricultural development on the water resources in the Minqin oasis of the lower reaches of the Shiyang River basin, and formulated future strategies for sustainable development of agriculture in the oasis areas. Results show that the water amount to the lower reaches of the Shiyang River had positive linear correlation of a determination coefficient (R²) of 0.82 with the natural water amount from the upper reaches during the period 1956-1973, when only natural factors causing the decrease in water amount to the Minqin oasis were accounted for. However, the marked linear correlation had been completely changed since 1973 due to water resources utilization by intensified human activities in the middle reaches in the Wuwei oasis. The agricultural water footprint of the Wuwei oasis increased rapidly from 158 × 106m³ in the year 1950 to 1 598 × 106m³ in the year 2006. In particular, the water footprint of food crops accounted for the highest proportion of agricultural water footprints. The increased agricultural water footprint in the Wuwei oasis showed significant negative linear correlation of a R² of 0.7983 with the decreased water amount to the Minqin oasis. Preliminary analysis indicate that an increase in agricultural water footprint of 100×10⁶m³ in the Wuwei oasis would cause a decrease in water amount of 25.43×10⁶m³ in the Minqin oasis across the past 40 years. On the other hand, the increased water footprint of food crops in the Wuwei oasis showed significant negative linear correlation of a R² of 0.81 with the decreased water amount to the Minqin oasis. It was also indicated that an increase in agricultural water footprint of 100×10⁶ m³ in the Wuwei oasis would be likely to cause a decrease in water amount of 50.21×10⁶m³ in the Minqin oasis over the study period. Therefore, actions to control the scale of agricultural production, adjust the structure of agriculture, reduce the virtual water of agricultural products, and change the growth trend of agricultural water footprint in the Wuwei oasis should be taken to mitigate environmental degradation across the Minqin oasis.