澜沧江—湄公河流域水库建设对植被干旱的影响及驱动机制

Effect of reservoir construction on vegetation drought and its driving mechanisms in Lancang-Mekong River Basin

摘要

【目的】了解水库建设后气象-水文干旱对植被干旱的驱动过程，有助于提升流域对于植被干旱的监测和预警。【方法】以澜沧江—湄公河(LM)流域为研究区，基于三种干旱指数[标准化降水指数(SPI)、标准化径流指数(SRI)和植被状态指数(VCI)],分析了1982—2016年流域内气象-水文-植被干旱的演变特征，采用Pearson相关分析法和滞后性分析探讨了水库建设前后不同干旱指数之间的关系变化和响应时间(DRT)的变化，最后探讨气象-水文干旱对植被干旱的影响及驱动机制。【结果】结果表明，在1982—2016年期间，流域内气象和水文干旱呈现出近似的变化趋势，而植被干旱表现出显著的季节性变化及缓慢的年际增长趋势(0.02~0.37/a)。水库建设后，流域下游植被干旱与气象干旱的相关性显著减小，流域上游植被干旱与水文干旱的相关性显著增强且呈负相关。此外，植被干旱对气象干旱和水文干旱的响应时间变化显著。旱季期间，植被干旱对气象干旱的响应时间平均延长1.6个月，对水文干旱的响应时间在万象—巴色段缩短0.2个月，其余区域平均延长3.2个月；雨季期间，植被干旱对水文干旱的响应时间平均延长2.6个月；同时，植被干旱对气象干旱的响应时间在不同区域表现出不同的变化：在中国—清盛、清盛—万象、巴色—河口段的响应时间平均缩短2.3个月，而在万象—巴色段延长了3.8个月。【结论】研究结果表明流域内的水库建设缓解了澜沧江—湄公河流域的植被干旱现象。本文将有助于增强对水库建设的生态效益评估，以及提高对气象-水文-植被干旱响应过程的理解。

Abstract

[Objective] Understanding the driving processes of meteorological-hydrological droughts on vegetation drought after reservoir construction helps enhance monitoring and early warning systems for vegetation drought in river basins. [Methods] Focusing on the Lancang-Mekong(LM) River Basin, the evolution characteristics of meteorological, hydrological, and vegetation droughts from 1982 to 2016 were analyzed based on three drought indices: Standardized Precipitation Index(SPI), Standardized Runoff Index(SRI), and Vegetation Condition Index(VCI). Pearson correlation analysis and lag analysis were used to explore the variations in relationships between different drought indices and the variations in drought response time(DRT) before and after reservoir construction. Finally, the effects of meteorological-hydrological droughts on vegetation drought and their driving mechanisms were investigated. [Results] The result showed that during the period from 1982 to 2016, meteorological-hydrological droughts in the basin exhibited similar trends, while vegetation drought showed significant seasonal variations and a gradual inter-annual increasing trend(0.02~0.37/a). After reservoir construction, the correlation between vegetation drought and meteorological drought decreased significantly in the downstream areas, while the correlation between vegetation drought and hydrological drought increased significantly in the upstream areas, showing a negative relationship. Additionally, significant changes were observed in the response time of vegetation drought to meteorological and hydrological droughts. During the dry season, the response time of vegetation drought to meteorological drought extended by an average of 1.6 months, while the response time to hydrological drought shortened by 0.2 months in the Vientiane-Pakse region, and extended by an average of 3.2 months in other regions. During the wet season, the response time of vegetation drought to hydrological drought extended by an average of 2.6 months. Furthermore, the response time of vegetation drought to meteorological drought varied across different regions: it decreased by 2.3 months on average in the China-Chiang Saen, Chiang Saen-Vientiane, and Pakse-Mouth regions, but increased by 3.8 months in the Vientiane-Pakse region. [Conclusion] The result indicate that reservoir construction in the basin alleviates vegetation drought in the Lancang-Mekong River Basin. The findings can enhance the ecological benefit evaluation of reservoir construction and improve the understanding of the response processes of meteorological, hydrological, and vegetation droughts.

关键词

澜沧江—湄公河流域 / 水库建设 / 气象-水文干旱 / 植被干旱 / 响应关系 / 影响因素

Key words

Langcang-Mekong River Basin / reservoir construction / meteorological-hydrological droughts / vegetation drought / response relationship / influencing factors

基金资助

国家重点研发计划项目(2021YFC3000201)