Spatiotemporal Variability of Rainfall in Central Guizhou: Multi-Time Scale Analysis and Implications for Climate Change Adaptation

Precipitation plays a critical role in the global water cycle, with its spatial distribution and variations significantly impacting both the environment and socio-economic systems, making it central to climate change research. This study investigates the spatiotemporal evolution of rainfall intensity and frequency in central Guizhou, China, using monthly data from 56 rain gauge stations (1965–2016). The analysis employs the Precipitation Anomaly Index (PAI) and P-III distribution to examine rainfall patterns across time scales of 3 to 12 months. Key findings include: (1) Rainfall intensity shows an "N-shaped" trend, with an increase from the 1960s to 1980s, followed by a decline and gradual recovery through the 2010s. The proportion of wet years peaked in the 1970s (47.55%), rising to 69.39% by the 2010s. (2) Rainfall frequency was highest during normal years (62.8%), with medium-frequency events becoming more dominant over time. (3) Significant differences in rainfall intensity were most pronounced at 9-month and 12-month scales, with rainfall frequency exhibiting significant variability across all time scales. This research highlights the multi-scale nature of rainfall patterns in central Guizhou, offering valuable insights for hydrological management and climate adaptation in karst regions.