Extraction And Study Of Drought Events In China Based On Standardized Precipitation Index

Meteorological drought events are one of the important events affecting human life.Serious meteorological drought events can develop into drought disasters.In China,meteorological drought events occur frequently and have a huge impact,which is extremely detrimental to the development of people's lives and industrial and agricultural production.Therefore,it is imminent to study the characteristics and development trend of drought events.This paper is mainly based on the monthly standardized precipitation index from January 1961 to November 2016 in China.In this study,after establishing a drought event model for the research perspective,the paper quantitatively studies the spatial,temporal and intensity properties of drought events through digital and imagery methods.This paper explores the frequency characteristics of the model under seasonal characteristics and the area proportion of drought events under continuous long-term effects.Therefore,combining the intensity attributes of the occurrence frequency of drought events with spatial attributes such as their impact scope,the drought events were analyzed from the three perspectives of frequency intensity,sweep range,and time duration.The following conclusions were obtained:(1)The overall drought event in the country is more obvious.The frequency of drought events on the southeastern side of the Hu Huanyong Line is higher than that on the northwest side of the Hu Huanyong Line as a whole.Frequent changes in the frequency of the area gathered on both sides of the Hu Huanyong line.Therefore,the development trend of drought events is positively related to the formation mechanism of Hu Huanyong Line,which proves to some extent that the development of drought events in China is closely related to the physical geography,social development and population activity.(2)In the geographical space,special drought events are generally the core area of drought events.According to the statistics of the frequency of drought events according to the seasons,it was found that In all regions,the most frequent drought event was the summer drought event.;The northeast,northwest,and southwest regions are dominated by spring,summer,and autumn droughts;North China is dominated by summer and autumn droughts;and east and central and southern regions are dominated by spring and summer droughts.(3)According to the statistics of the proportion of the area affected by drought events,the area with the highest proportion was middle-level drought,while the area affected by different levels of drought events in East China tended to fluctuate.The remaining areas were relatively stable.The largest area affected by the drought in the northwest is the light drought incident.(4)During the comprehensive assessment of the region where the drought occurred,an evaluation system based on the two dimensions of frequency and area ratio was established,revealing that the northeastern region is the most severe drought event affected region,and the northwestern region is the most minor drought event.Affect the area.This conclusion is consistent with the trend of frequency distribution of national drought events,which further validates the reference value of the data and the accuracy of the model.