| In recent years,under the influence of global warming,the frequency of drought events in China has increased,and the scope and duration of drought events have shown an expanding trend,which has seriously affected agricultural production and caused great losses to the national economy.Shandong Province is located at the junction of the economic zone along the Yellow River and the economic zone around the Bohai Sea.It has sufficient sunshine time throughout the year.However,due to the influence of temperate monsoon climate,precipitation is unevenly distributed and is prone to extreme meteorological drought disasters.According to the statistics of "China Flood and Drought Disaster Bulletin"issued by the Ministry of Water Resources,in recent years,drought and flood disasters have occurred frequently in Shandong Province,and the affected crops have a larger area.Studying the spatial and temporal characteristics of drought events in Shandong Province is of great significance for government agencies to formulate disaster prevention and mitigation strategies.Based on the monthly precipitation and monthly mean temperature data of 18 meteorological observation stations in Shandong Province from 1961 to 2016,the standardized precipitation and evapotranspiration index(SPEI)series of different scales are calculated.The spatial and temporal characteristics of drought in Shandong Province are analyzed from different scales by combining Mann-kendall trend test and empirical orthogonal function(EOF).Meanwhile,based on the natural and socio-economic factors in shandong,the risk of agrometeorological drought in the affected areas was analyzed from the perspectives of vulnerability and recovery,and a reasonable agrometeorological drought risk assessment system was established.The risk of agricultural drought in Shandong was evaluated,and the corresponding measures for drought prevention and disaster reduction were put forward.The study found that:(1)The change of annual SPEI values is basically consistent with the occurrence time of drought disasters in Shandong in past years,and shows an obvious trend of drought.The results of mutation test show that the annual drought phenomenon in Shandong suddenly intensified in 1976.Spatially,the probability of drought in Shandong Province is higher,and in the years of drought,most of them are local drought,followed by global drought,indicating that there is a certain spatial difference in the occurrence of drought in Shandong Province.Drought is prone to occur in the central region,and extreme drought is prone to occur in the northern part of Shandong Province.Monthly-scale SPEI shows that the phenomenon of inter-monthly drought also shows a trend of drought.Since 1993,the phenomenon of extreme drought and flood has increased in Shandong Province.Extreme precipitation and periodic drought are frequent.Catastrophe test shows that the phenomenon of inter-monthly drought suddenly intensified in 1998.Spatially,the frequency of drought months in most areas of Shandong Province is at a high level,which is more prone to occur in the central region,and the frequency of drought above the middle-drought level is at a high level,which mainly concentrated in the south-central and north-central areas of Shandong Province.(2)In recent years,SPEI in Shandong Province has shown a downward trend in all seasons,with the most obvious decline in spring,followed by summer and autumn,and no obvious drought in winter.The M-K mutation test curves of the four seasons showed that there was a sudden change to drought in spring and autumn in 1977,but no change in summer and winter.Spring drought is easy to occur in Shandong,followed by autumn drought and summer drought.Spatially,spring drought is easy to occur in the southeastern region,and drought above moderate spring drought is easy to occur in the central and southern parts of Shandong Province;summer drought is at a high level in other areas except Shandong Peninsula and the northwest and southwest regions,and the frequency distribution above moderate summer drought is similar to the former;the frequency of autumn drought is similar to that of summer drought,mainly concentrated in the central and southwestern parts of Shandong Province.The frequency of drought above mid-autumn drought in the eastern part is significantly higher than that in the western part in the southern and Northern regions,while the frequency of winter drought is mainly concentrated in the central part of Shandong Province.(3)By decomposing SPEI12 into two different modes,it is concluded that there are two distinct characteristics of drought change in Shandong.One is that the occurrence of drought in Shandong has a certain degree of integrity,and the other is that in the context of overall drought,to some extent,the coastal and inland areas of Shandong Province have the characteristics of anti-phase change.(4)Taking 132 counties and districts in Shandong Province as research units,this paper chooses reasonable natural and social economic factors as evaluation indicators,constructs the drought risk assessment system of agricultural disasters in Shandong Province,and obtains the drought risk distribution map of Shandong Province.The results show that among the 17 risk assessment indicators,per capita arable land area,multiple cropping index,per unit fertilizer use,per capita GDP,irrigation index,per capita water resources,and the proportion of agriculture to GDP are the main influencing factors.The risk of agrometeorological drought disaster in most counties and districts in Shandong province is at a high level.In terms of geographical distribution,high-risk areas are mainly concentrated in peninsula,central Shandong and southern Shandong,mainly including Weifang,Qingdao,Zaozhuang,Jining,Rizhao,etc.Severe-risk areas are also widely distributed in Peninsula areas and central Shandong Province,such as Yantai,Jinan,etc.Moderate risk areas mainly include northwest Shandong,such as Dezhou,Binzhou,Dongying,etc.Mild risk areas mainly distribute in southern Shandong,such as Linyi. |
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