Xinjiang, a unique natural unit, is sensitive to the global warming. Studies on the spatial-temporal variation and impacts of drought and wetness in Xinjiang have a significant effect on the adaptability of future climate change. Based on observations of monthly mean temperature, monthly precipitation, and calculated standardized precipitation evapotranspiration index (SPEI), this paper analyzes the drying trend and impacts of climate change on the water resources and vegetation dynamics over Xinjiang, China. The results can be shown as follows: (1) The climate experienced a significant shift from warm-wet to warm-dry over Xinjiang in 1997 based on the SPEI data, after which the frequency, trend, dry months and percentage of stations of drought increased sharply. (2) The increased meteorological drought severity had a direct effect on the normalized difference vegetation index (NDVI) and river discharge. The NDVI exhibited a significant decrease during the period 1998-2015 compared with 1982-1997, which was found to be caused by increased soil moisture loss. (3) The hydrological drought was very complicated and not entirely comparable to the SPEI droughts. Hydrological records indicate that runoff in most rivers in the Tianshan Mountains has increased, while it remained stable or even decreased slightly in the Kunlun Mountains over the past 20 years. The runoff in Xinjiang is strongly influenced by glacial melt, and it is getting worse due to global warming. The climatic shift and intensified climate extremes over Xinjiang have resulted in SPEI-drought severity. These changes also have possibly intensified the instability of water cycle system and ecosystem. The results provide valuable decision-making reference for the regional drought disaster prevention, reduction and emergency management over Xinjiang, China.

Keywords： wet-to-dry shift ; water resources ; ecological degradation ; impact assessment ; Xinjiang