Spatio-temporal evolution of drought and flood disaster chains in Baoji area from 1368 to 1911

摘要

Based on the collation and statistical analysis of flood and drought information in Baoji area from 1368 to 1911,and in the context of climate change,we investigated the spatio-temporal evolution characteristics of drought and flood disaster chains in this area during the Ming and Qing dynasties using the methods of moving average,cumulative anomaly and wavelet analysis.The results are as follows:(1) We found a total of 297 drought and flood events from 1368 to 1911 in Baoji.Among these events,droughts and floods occurred separately 191 and 106 times,which accounted for 64.31％ and 35.69％ of the total events,respectively.(2) We observed distinct characteristics of flood and drought events in Baoji in different phases.The climate was relatively dry from 1368 to 1644.A fluctuant climate phase with both floods and droughts occurred from 1645 to 1804.The climate was relatively wet from 1805 to 1911.Moreover,we observed a pattern of alternating dry and wet periods from 1368 to 1911.In addition,3 oscillation periods of drought and flood events occurred around 70 a,110 a and 170 a,which corresponded to sunspot cycles.(3) We also observed an obvious spatial difference in drought and flood events in Baoji.The northern and eastern parts of Weihe River basin were regions with both frequent droughts and floods.(4) The sequential appearance of drought and flood disaster chains in Baoji from 1368 to 1911 was in response to global climate change.Since the 1760s,global climatic deterioration has frequently led to extreme drought and flood events.