三江源区多尺度水文干旱特征及植被的响应

采用标准化降水指数SPI和遥感植被指数(NDVI、EVI)量化1961—2018年三江源区的生长季植被和水文干旱的演化特性，基于Mann-Kendall趋势检验法分析了三江源区1961—2018年干旱与植被的时空演变趋势，并基于斯皮尔曼等级相关系数进行了不同干旱变量与植被指数的相关性分析。结果表明： 三江源区季度干旱事件发生于1963年、1966年、1984年、1992年、2000年和2017年；春季有显著湿润化现象（平均趋势特征值Z=228），秋季澜沧江源和长江源中部有不显著干旱威胁；5月黄河源以北地区有显著植被增加趋势，9月长江源中部与澜沧江源有不显著植被退化趋势，2000—2018年植被变化趋势是北部强于南部、西部强于东部；21世纪以来，干旱事件与植被有一定的响应关系，SPI3与植被指数显著正相关。

Multi-scale hydrological drought characteristics and vegetation responses in the Three-River-Source Region

The standardized precipitation index SPI and remote sensing vegetation index (NDVI, EVI) were used to quantify the evolution characteristics of growing season vegetation and hydrological drought in the Three River Source Region (TRSR) from 1961 to 2018. The spatio-temporal evolution trends of drought and vegetation in the Three River Source Region from 1961 to 2018 were analyzed based on the Mann-Kendall trend test. In addition, the spatio-temporal evolution trend of vegetation, and the correlation between different drought variables and vegetation index was analyzed based on the Spearman''s level correlation coefficient. The results show that the seasonal drought events in the study area occurred in 1963, 1966, 1984, 1992, 2000 and 2017, there was significant humidification in spring (mean trend characteristic value Z=2.28), and both the source of Lancang River and the middle of the source of Yangtze River in autumn faced a non-significant drought threat. In May, there was a significant increase of vegetation in northern of the Yellow River source, while there was an insignificant trend of vegetation degradation in the middle of Yangtze River source and Lancang River source in September. The variation trend of vegetation is that the north is stronger than the south and the west is stronger than the east from 2000 to 2018. Since the 21st century, drought events have a certain response relationship with vegetation, and SPI3 has a significant positive correlation with the vegetation index.