Three Drought Indices In Guizhou Province's Agriculture Applicability Analysis In The Study Of Drought Spatio-temporal Differentiation

Drought is a common phenomenon,and different degrees of drought will have a huge impact on the natural,ecological environment and the development of human society in various regions.Agricultural drought has a more significant impact on national food security and social and economic security,with the characteristics of high frequency,wide range and long duration.In Guizhou area,karst is well developed,soil erosion is serious,and soil water retention capacity is lower than that in northern areas.Therefore,how to effectively monitor the temporal and spatial differentiation of soil water content,vegetation growth and soil relative humidity index changes is of great significance to the development of the agricultural economy in the region and the formulation of drought prevention and disaster control measures.This paper takes Guizhou Province as the research area,uses the MODIS vegetation index data and land surface temperature data of Guizhou Province from2000 to 2019 to establish the soil water content monitoring index,the temperature vegetation drought index(TVDI),and the meteorological data to establish the relative soil moisture and drought monitoring index.Humidity Index(MI),using MODIS remote sensing data to establish the vegetation status index of agricultural drought monitoring index vegetation status index(VCI).Combined with agricultural statistics,the applicability of the three monitoring indicators in the study area was demonstrated and analyzed using grain production data from 2000 to 2018,and the results of the study were analyzed using seasonal scale rainfall data,surface temperature,and slope.Discussion,the results showed that:(1)From the perspective of time characteristics,the inter-annual variation of agricultural drought is more obvious.The drought in spring and winter is stronger than that in summer and autumn.From an annual scale,the interannual variation of agricultural drought based on different indexes is not large.From a spatial point of view,the drought in the west is stronger than that in the central and eastern regions,and the fluctuation of the drought trend in each year is relatively stable.(2)Different drought indices are suitable for agricultural drought monitoring in different periods,MI is suitable for agricultural drought monitoring in the winter half of the year,TVDI is suitable for agricultural drought monitoring in the summer half of the year,and VCI is suitable for agricultural drought monitoring in various periods and time scales.(3)The influencing factors of agricultural drought are not single.A single drought factor will not completely control the amount of grain output.The amount of grain output is not entirely affected by the degree of agricultural drought,but is also restricted by many other factors.(4)Rainfall affects the occurrence of agricultural drought to a certain extent,but rainfall will not completely control the occurrence of drought,and differences in surface temperature and temperature will also cause spatial and temporal differences in agricultural drought.