| In recent years, extreme weather events continue to endanger the national economic and social security under global warming backgrounds, and regional sustainable development is faced with severe challenges. Abnormal weather which floods, droughts, heat waves and other weather disasters occurred frequently.With the continuous deepening of global change research, the characteristics of the climate change and predisposing factors should be pay more attention to further analysis, a series of changes caused by climate change have had a serious impact on agriculture, environment, economic development of different areas, the characteristics changes of the study area have practical significance on regional construction and development, especially the study on meteorological disasters under global warming backgrounds will help the region provide reference to cope with global change and regional disaster prevention and mitigation construction.Based on precipitation and temperature data of39National Meteorological reference sites in Sichuan Province during1961-2010, using methods of linear analysis, Mann-Kendall test, Z index, this paper analyzed the spatial and temporal variations of precipitation and temperature in Sichuan Province during the past50years;Based on droughts and floods index system of Z index, the paper summarized characteristics of the regional changes, discussed tendency of the year of regional droughts and floods using commensurable method, extracted the probable value of the year of future droughts and floods effectively. Finally, according to the regional characteristics of droughts and floods and other socio-economic information in Sichuan Province, the paper evaluated the risk of droughts and floods, exposure, vulnerability, disaster prevention and mitigation, as well as integrated risk. The main conclusions were as follows:(1) In recent50years, the average temperature had a slow upward trend in Sichuan Province. The warming trend of the average minimum temperature was the most significant and the linear trend rate of the average temperature was0.18℃/10a. The temperature mutations occurred in1994. In1960s-1980s, the temperature was on the low side as a whole and entered in a prominent warming stage since the1990s. The precipitation had a diminishing fluctuation change and the linear trend rate was-8.7mm /10a. The spring precipitation had increased and autumn precipitation had a significant downward trend. And the summer precipitation and winter precipitation had a little change and the total amount of them had weak downward trend.(2)The overall annual precipitation in the province presented the distribution pattern of "more in the east and less in the west’", the precipitation of the basin was significantly higher than the Western Plateau of Sichuan region, which the distribution characteristic was decreasing from the southeast to the northwest. There were three characteristics of the change area, the Western Plateau of Sichuan region was the area which precipitation was increased, the linear trend of precipitation change was not significant in eastern Sichuan Basin, there was no obvious trend of change, while others except the eastern Sichuan Basin and the Southwestern Mountain of Sichuan region the precipitation presented a decreasing trend. The difference in spatial distribution of seasonal precipitation changes was also obvious; the precipitation was still to increase in the most western regions of Western Plateau of Sichuan region, to mainly reduce in eastern Sichuan Basin. But the area divisions of each season were slightly different.(3)Rain waterlogging of the area had a weak reducing trend and the drought trend had increased. In the recent50years, more serious drought occurred after1990s.The drought intensity was higher than that of rain waterlogging in spring, nearly10years the drought index was at a lower value, the trend of drought and flood were becoming flat. Drought and flood occurred most frequent and severe in summer, in the past20years the stability of summer precipitation was weak, volatility was increased, and may more frequent drought and flood in summer. More partial year of waterlogging occurred in autumn, autumn waterlogging may gradually reduce but autumn drought may become main meteorological disasters in autumn. There was more severe drought occurred in winter, great drought and special drought appear more easily.(4)This paper judged the trend of drought, waterlogging in the region of Sichuan and seasonal drought in Dujiangyan using commensurable method. The results showed that drought signal was relatively stronger in2013, strong of waterlogging signal in2014in the region of Sichuan. In Dujiangyan, the spring drought signal was stronger in2016, strong of summer drought signal in2017, autumn drought signal in2013and winter drought signal in2020.(5)The most risk area was mainly located in the eastern part of Sichuan Basin and the south of Western Plateau of Sichuan. The highest exposure area mainly include Chengdu, Deyang, Ziyang, Neijiang and Zigong where the population density and economic density was high; the low exposure area was located in Aba Tibetan Autonomous Prefecture, Ganzi Tibetan Autonomous Prefecture, Yi Autonomous Prefecture of Liangshan and Ya ’an, etc. The highest vulnerability areas were BaZhong and Guang’an, low vulnerability areas include Chengdu, Mianyang, Ziyang and Panzhihua. Cities with the high estability of prevention and mitigation were Chengdu and Panzhihua, with low ability of disaster prevention and mitigation were Aba Tibetan Autonomous Prefecture and Ganzi Tibetan Autonomous Prefecture in the Western Plateau of Sichuan region. On the basis of comprehensive analysis, the regions with the highest drought and flood risk degree were Bazhong and Dazhou in eastern Sichuan Basin, with higher risk degree were ten cities including Guangyuan, Nanchong, Guang’an, Mianyang, Deyang, Suining, Ziyang, Meishan, Neijiang and Yibin, with medium risk include the cities of Ya ’an, Leshan, Zigong, Luzhou, Yi Autonomous Prefecture of Liangshan and Panzhihua, with the lowest drought and flood risk were Chengdu, Ganzi Tibetan Autonomous Prefecture and Aba Tibetan Autonomous Prefecture. |
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