Abstract:
Drought and flood index is an important means of drought and flood monitoring and forecasting. Based on the daily precipitation data of 274 rainfall stations in the upper reaches of the Yangtze River from 1961 to 2019, this paper calculates the SPI (standardized precipitation index)of each station, and analyzes the multi- scale temporal and spatial variation characteristics of drought and flood in the upper reaches of the Yangtze River in recent 60 years. The results show that the drought events in the upper reaches of the Yangtze River mostly occur in autumns and winters, and the flood events mostly occur in springs and winters. The frequency of drought and flood events of different ranges changes obviously in the upper reaches of the Yangtze River, the number of drought and flood events in the whole region is close to each other, but the regional flood is more than the drought, partial and local drought is more than flood. The spatial heterogeneity of drought and flood distribution in each season in the upper reaches of the Yangtze River is significant. The high-value areas of drought and flood frequency are distributed sporadically, and the large-scale drought and flood frequent areas are rare. In recent years, the western part of the upper reaches of the Yangtze River tends to flood, while the southern and eastern part tends to drought. The change of winter and spring is more obvious, while the change of summer and autumn is relatively weak.