Study on the propagation thresholds from meteorological drought to agricultural drought in arid and semi-arid region
[Objective]The aims of this study are to explore the order of drought propagation and propagation thresholds of different types of droughts,and to provide scientific reference for monitoring,prediction and early warning.[Methods]The arid and semi-arid region of Northeast Asia was taken as the study area.Standardized precipitation evapotranspiration index was used to characterize meteorological drought.Standardized soil moisture index and normalized difference vegetation index were used to characterize agricultural droughts from the perspectives of soil moisture and vegetation.The Run theory was used to identify drought events and their characteristics and to match drought events.The thresholds for drought propagation were determined based on the Copula function.[Results](1)Drought in the study area showed an increasing trend from 1982 to 2014.The increasing trend of meteorological drought and soil moisture drought was greater than that of vegetation drought.(2)The propagation rate and average propagation time of meteorological drought to soil moisture drought was greater than that of vegetation drought,and the sequence of propagation was as follows:meteorological drought propagated to vegetation drought to soil water drought.The thresholds of drought propagation increased with the increase of drought level.(3)The propagation threshold from meteorological drought to soil moisture drought in this area was smaller than that of vegetation drought.[Conclusion]Agricultural drought triggered by meteorological drought in the arid and semi-arid region of Northeast Asia threatens food security and ecological safety.There are differences in drought propagation patterns and propagation thresholds between soils and vegetation,so that ecological protection and restoration measures should be formulated according to local conditions.
万方数据
维普
