三峡入库径流变化归因多方法识别

Multi-method Identification of Attribution of Runoff Changes in Three Gorges

受气候变化、人类活动等因素影响,近年来长江上游径流特性发生明显变化,给长江上游流域水资源的合理开发利用、三峡及上游水库群等国家战略淡水资源库作用的发挥带来诸多挑战,径流变化归因定量识别的研究对流域水资源的开发利用具有重要的意义。基于1951-2013年三峡入库径流序列资料,采用Mann-Kendall法、Spearman法、Pettitt法等统计方法,诊断了三峡入库径流的演变规律;基于同期气象、土地利用等资料,分别利用气候弹性模型、水热耦合平衡模型、SWAT模型定量识别三峡入库流量变化原因。结果表明:(1)三峡入库径流在1993年前后发生明显的突变,1993年以前为径流受气候变化和人类活动影响较小的相对天然期,1993年以后径流为受气候变化和人类活动影响较大的变化期;(2)研究期三峡入库径流发生了显著减少,减少速率为8.8 mm/10 a,长江上游大规模的人类活动是三峡入库径流减少的主要原因,降水量减少和气温上升是径流减少的重要原因;(3)气候弹性模型法与SWAT模型法归因识别结果一致,水热耦合平衡模型法低估了人类活动这一引起三峡入库径流减少的主要因素;(4)考虑土地利用时空变异的SWAT模型方法较传统“两段论”的方法能够更好地刻画径流演变的原因。研究成果对指导三峡水库水资源综合利用和长江上游水资源的合理开发具有重要意义。

Due to climate change and human activities,the runoff characteristics of the upper Yangtze River have changed significantly in recent years,bringing many challenges to the development and utilization of water resources in the upper Yangtze River Basin and the functions of national strategic freshwater resource reservoirs such as the Three Gorges and the upstream reservoir group.Attribution analysis of runoff changes is of great importance to the development and utilization of water resources in the basin.Based on the observed runoff data from 1951 to 2013,statistical methods such as Mann-Kendall test,Spearman test and Pettitt test are used to diagnose the variation patterns of the Three Gorges inflow runoff.Based on the meteorological and land use data of the same period,the causes of the variation of the Three Gorges inflow runoff are further quantitatively analyzed by using the climate elasticity method,the water-energy balance equation and the SWAT.The results show that:①the inflow runoff of the Three Gorges was significantly changed around 1993,before 1993 the runoff was relatively natural and less affected by climate change and human activities,and after 1993 the runoff changed and was more affected.②During the study period,the inflow runoff from the Three Gorges decreased significantly,at a rate of 8.8 mm/10 a.Large-scale human activities in the upper Yangtze River were the main cause of the decrease in inflow runoff into the Three Gorges,while the decrease in precipitation and the increase in temperature were important causes.③The attribution results of the climate elasticity approach are consistent with the SWAT-based method,while the water-energy balance approach underestimates the impact of human activities on runoff.④SWAT takes into account the spatial and temporal changes in land use,can better describe the causes of runoff changes than the traditional“two-stage”method.These results are important to guiding the comprehensive utilization of water resources in the Three Gorges Reservoir and the rational development of water resources in the upper Yangtze River.