LAUSR

The quantitative analysis of drought is crucial essential for drought risk assessment. The standardized precipitation evapotranspiration index (SPEI) has been widely used as an effective approach to quantitatively analyze the trends, duration, frequency, and severity of drought. However, how to calculate the evapotranspiration is big challenge for the reliable and accuracy of SPEI results. The most previous studies calculated SPEI based on an empirical evapotranspiration equation, such as the Thornthwaite method, rather than the physical Penman⁃Monteith equation. Moreover, majority of the studies analyzed the spatio⁃temporal pattern of the index without linkage of the relationship between the climactic drought index and actual cropland drought areas. This study utilized SPEI based on the Penman⁃ Monteith equation to explore the variations of drought frequency and duration during 1963—2014 in 3H Plain, and established the relationship between SPEI and the actual field drought areas by Pearson correlation in Henan, Hebei, and