Spatial-temporal variation characteristics and influencing factors of drought in the Loess Plateau based on daily scale SPEI
[Objective]The aims of this study are to investigate the spatial and temporal characteristics of meteorological drought and its influencing factors in the Loess Plateau region,and to provide scientific support for drought monitoring,dry-crop agricultural food production,water resource management and ecological restoration construction in this region.[Methods]Based on the day-by-day meteorological data of 119 stations in the Loess Plateau region from 1957 to 2019,the daily-scale potential evapotranspiration(PET)and standardized precipitation evapotranspiration index(SPEI)were calculated using the FAO Penman-Monteith formula.Theil-Sen Median slope estimation and Mann-Kendall trend analysis were used to explore the distribution characteristics and trends of the number of drought days,the number and intensity of drought events.Meanwhile,Pearson correlation coefficient was used to analyze the relationship between meteorological factors and drought indicators.The impact of human activities on meteorological drought was explored in combination with the land use type transfer matrix.[Results](1)The daily-scale SPEI was more accurate than the monthly-scale SPEI in identifying the number of drought days,the number of drought events and intensity.(2)The number of drought events increased in the northwestern part of the Loess Plateau from 1957 to 2019,and the intensity of drought in most regions showed an increasing trend,with the number of days of different types of droughts decreasing.(3)There was a clear trend of drying in the southeastern and northwestern regions of the Loess Plateau,while the northern and southern regions show a trend of wetting.(4)There was a moderate correlation between meteorological factors and drought indicators,and the land use/surface cover affected meteorological droughts to a certain extent in the Loess Plateau region.[Conclusions]Meteorological drought in the Loess Plateau region is influenced by both climatic factors and human activities,and its spatial and temporal changes are characterized by complexity.The results of the study can provide an important scientific basis for drought monitoring and management in this region.
Loess Plateaudaily scale SPEImeteorological droughtTheil-Sen median slope estimation
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