Spatial And Temporal Distribution Characteristics Of Drought In Shandong Province In The Past 60 Years

In the current background of global warming and climate change,drought with frequent occurrence and great harm has a more and more negative impact on human life,causing widespread concern and research.Among all kinds of natural disasters,drought causes the biggest loss,which seriously restricts the development of social economy and will be more serious in the future.The complexity,influencing factors,driving force and physical mechanism of drought are all the problems for researchers.Therefore,in view of drought,we need to continue to study and explore.All the data in this paper are based on the statistical data of 23 stations in the province,involving all the precipitation data in the past 57 years.The conclusions are as follows:(1)The spatial-temporal analysis of precipitation in Shandong Province is carried out.The precipitation is mainly concentrated in the southeast coastal area and gradually decreases to the northwest.Combined with the current precipitation to implement EOF analysis,the final results show that the distribution of precipitation in Shandong Province is relatively consistent,which shows that the precipitation in the whole region presents either a large or a small distribution form.Hurst index analysis can find that in the whole province,the trend of upward development in four seasons.According to the analysis of the cloud model results,the precipitation in summer is very large,while in winter it is relatively stable,basically there will be no significant change.(2)Based on the analysis of drought time series in Shandong Province,the SPI drought index was selected from the six drought index's drought frequency and Historical Drought records.It is calculated that the frequency of drought in Shandong Province is about 30.66%,and the intensity of drought in Shandong Province is about 0.57-1.63,mainly light and medium drought.Finally,the analysis of the ratio of drought to sub drought shows that the situation of overall drought in Shandong Province first occurred in the 1980 s,and it lasted until the beginning of this century,while regional drought always existed.The Kriging interpolation method in ArcGIS is used to understand the distribution map of drought frequency in Shandong Province.The most serious areas of drought in Shandong Province are the east of Jining,Dongying,Binzhou and the southwest of Shandong Peninsula,while the probability of drought in the central area is relatively small.In spring,drought mainly occurs in the northwest inland area,in summer,it mainly occurs in the north and south,and in Thailand In autumn,the drought in the East is more serious than that in the West.In winter,the frequency of drought is between 26% and 29.21%,and gradually decreases from north to south.Based on the spatial analysis of drought distribution,the drought in Shandong Province can be roughly divided into four regions.The frequency of drought in region I is the highest and prone to drought events.The frequency and intensity of drought in spring and winter are high,because the warm and humid air flow in the southeast direction is blocked by mountains.The drought situation in area II is better than that in area I.The drought mainly occurs in the eastern part of the area,with the exception of Mount Tai.The third area has the best drought condition,low frequency and low intensity.The drought situation in Area IV is slightly worse than that in Area III,and the drought events are mainly concentrated in the southeast.(4)Precipitation forecast,the key factor of drought is precipitation.In this study,the grey model,BP neural network model and grey neural network model are used to study and analyze,so as to grasp the future drought situation in Shandong Province.Through the comparative analysis of the data in the three models,it can be determined that the prediction result of the grey neural model is the most accurate,and can meet the test standards and requirements.