Abstract:

The paper aims to analyze the spatial and temporal distribution characteristics of drought-flood in southwest Shandong. Based on the monthly precipitation data of 9 counties in the region from 1971 to 2015, we analyzed the variation characteristics of drought-flood by using the standardized precipitation index with different time scales. The results showed that: the flood was more frequent in the 1970s, drought increased in the 1980s, while it turned into flood in the 1990s, and drought continued to weaken, flood increased in the 2000s; the characteristics of seasonal changes all showed drought and flood occurred alternately while the flood occurred more frequently in summer, the linear trend of SPI in spring, summer, autumn were relatively stable, it had no obvious change trend, the flood in winter showed a slightly increasing trend while drought decreased with no obvious change trend; the trend of drought-flood in 3 areas were basically identical, showing an overall watering trend which did not reach the significant level; the rate of drought-flood was relatively stable from 1970s to the early 1990s while was the maximum in the early 21 ^st century, and there was obvious dry-wet change from the late 1990s to the early 21 ^st century. In southwest Shandong, the change of drought-flood has obvious stages and the occurrence is extremely frequent, and the whole process is flood-drought-flood.

Key words: drought-flood, evolution, standardized precipitation index, alternate, southwest Shandong, spatial and temporal distribution