Response Mechanism Of Agricultural Drought To Meteorological Drought Based On Different Time Scales In Guizhou Province

Drought is one of the natural disasters affecting my country’s grain production,water shortage and ecological environment deterioration.Guizhou Province has a good ecological environment,but the karst landform is strongly developed,the problem of karst rocky desertification is prominent,and the ecological foundation is fragile,which seriously hinders the development of its agricultural economy.Since 2000,Guizhou Province has carried out ecological construction projects such as returning farmland to forests and grasslands,controlling rocky desertification,and closing hills for afforestation,actively responding to the impact of climate on the ecological environment.Therefore,accurate monitoring and evaluation of the occurrence of meteorological drought and agricultural drought in Guizhou Province and the relationship between the two are of great significance to the regulation and efficient use of water resources in Guizhou Province,and the prevention and mitigation of agricultural production.Based on this,based on remote sensing data and meteorological data,this paper uses the Standardized Precipitation Index(SPI),Standardized Precipitation Evapotranspiration Index(SPEI),and Vegetation State Index(VCI)to analyze the spatial and temporal characteristics of drought at different time scales.It also studies the correlation between meteorological drought and agricultural drought to illustrate the time lag characteristics of the transmission of meteorological drought to agricultural drought,in order to provide an effective scientific reference value for the prevention of drought in Guizhou Province.The main research results are as follows:(1)From 2000 to 2018,the SPI and SPEI values of different time scales in Guizhou Province showed an overall increasing trend,indicating that the drought situation in Guizhou Province was decreasing.The seasonal drought in Guizhou Province is dominated by spring drought,and the drought intensity is mainly light drought and moderate drought;droughts occur frequently throughout the province,mainly light and moderate droughts,and the frequency of moderate and extreme droughts is relatively low.(2)The SPI index and the SPEI index have good monitoring effects on the meteorological drought in Guizhou Province,but the monitoring accuracy of the drought occurrence time is different between the two;in general,the SPI index is more important than the SPEI index.(3)Based on the VCI index,the overall trend of seasonal and annual drought changes in Guizhou Province is that the slowing trend of drought in the eastern region is greater than that in the western region;the agricultural drought in Guizhou Province is dominated by light drought;the trend of seasonal drought intensity is increasing,The drought is most pronounced in spring,and the annual and seasonal spatial distribution characteristics of drought frequency are "high in the west and low in the east,high in the north and low in the south".(4)Combining the historical drought data in Guizhou Province,comparatively analyze the time and space accuracy of drought monitoring in Guizhou Province based on three drought indices.The analysis shows that the SPI and SPEI indexes can characterize the time of drought in Guizhou Province in detail,but the drought intensity monitoring results are lighter than the actual drought;the VCI index is more accurate in the agricultural drought monitoring results and the description of the spatial distribution characteristics of the drought is better than Site drought index.(5)By studying the correlation between meteorological drought index SPI,SPEI and agricultural drought index VCI at different time scales,the spatial and temporal characteristics of meteorological drought transmission to agricultural drought in Guizhou Province were analyzed.The results showed that the transmission of meteorological drought to agricultural drought in Guizhou Province had a time-lag.The response of agricultural drought to meteorological drought at interannual,seasonal and monthly scales had obvious time lag,and the lag time was 1month.The spatial sensitivity of agricultural drought to meteorological drought in western Guizhou is higher than that in eastern Guizhou.(6)To further verify the accuracy of the research results,a comparative analysis of the drought situation monitored by the VCI index after 1-3 months of meteorological drought and the actual drought situation showed that the lag period of agricultural drought to meteorological drought in Guizhou Province was 1 month.This conclusion is accurate.