Drought Index Model Construction And Drought Monitoring In Inner Mongolia Based On Multi-source Remote Sensing Data

Drought has always been recognized as one of the most serious natural disasters in the world.It is a recurring natural phenomenon with a wide range of influence and a large coverage area.It affects the production and life of human beings in terms of food security,social economy,and ecological environment.The development of human civilization has been plagued throughout history.In particular,global warming will lead to more frequent and severe drought events in the future,so drought monitoring is particularly important.Inner Mongolia is far away from the ocean and is blocked by the Greater Khingan Mountains.It is controlled by continental air masses throughout the year.Many places are drought-hit areas in China.The drought research in Inner Mongolia has important ecological and economic significance for protecting people's production and life.There are various types of drought monitoring indexes with different focuses but the index elements are relatively single.This paper comprehensively considered the influence of vegetation coverage,precipitation,surface temperature,elevation,soil effective water holding capacity and surface cover types on drought,and constructed a drought monitoring index.Compared with a drought index based on a single factor,it can effectively evaluate drought from multiple aspects,monitor the spatiotemporal characteristics of drought in Inner Mongolia more scientifically,effectively and objectively,and provide an effective reference for drought monitoring methods.This method was used to invert the comprehensive drought index in Inner Mongolia from March to November 2001-2019,and the methods including anomaly/cumulative anomaly,Sen-MK test,drought frequency,and future change trend Hurst index were used to analyze the spatial and temporal characteristics of drought in Inner Mongolia.The main conclusions are as follows:(1)Based on multi-source remote sensing data,comprehensively considering multiple factors,and using random forest algorithm,a comprehensive drought monitoring index suitable for Inner Mongolia was constructed.The relative humidity index,soil moisture data and field measured soil moisture data were used to verify and analyze the correlation of the index.The results were good and met the accuracy requirements.(2)Regarding the temporal and spatial distribution characteristics of drought on an annual scale(excluding winter),2011 was a turning point for drought relief from 2001 to 2019.Droughts in Inner Mongolia were mostly dominated by heavy and moderate droughts.Drought conditions in most areas were basically stable.The drought situation in the area accounting for 31.55% of the study area has been alleviated,and the area of drought deterioration is less,accounting for 0.105%;except for parts of the Daxinganling Mountains where there is no drought,the rest of the league cities have different degrees of drought.(3)With regard to the seasonal and spatial distribution characteristics of droughts on a seasonal scale,2013,2011,and 2009 were the main turning points of drought changes in spring,summer and autumn,respectively.There was an increasing trend in spring drought,and a slowing trend in summer and autumn drought.Spring and autumn droughts were more serious,and the summer drought was the lightest.No matter in spring,summer,and autumn,the drought in areas that account for more than 76% of the study area remained basically unchanged.The order of drought deterioration area was spring>autumn>summer,and the order of drought improvement area was summer>autumn>spring.The frequency of drought in spring,summer and autumn was higher.