Abstract:

Based on multi-time scale SPEI representing meteorological drought, and the historical multi-layers soil volumetric water content data from agro-meteorological stations as representative factors for agricultural drought, we explored the coupling relationship between meteorological drought and agricultural drought in subtropical monsoon climate region in eastern China, continental monsoon climate region in central China and moderate temperature arid climate region in western China, and conducted the analysis in combine with time delay as well. The results showed that: the overall correlation in the central region was the best, the worst was in the west, among them, the high correlation region had differences in different climatic regions, the longer time-scale of SPEI was more relevant with soil moisture in drier regions, the optimal time scale in western, central and eastern regions was September, June, April, respectively; precipitation infiltrated from soil surface to 50 cm depth within a month and then stored near that depth, to replenish surface soil moisture in the event of drought. Meteorological drought and agricultural drought are both water shortage phenomena, but the response time is not the same. Exploring the coupling relationship between the two is significant for enhancing the awareness of drought mechanism, as well as improving the ability of drought monitoring and mitigating and preventing drought.

Key words: the standardized precipitation and evapotranspiration index, soil volumetric water content, Pearson correlation coefficient, time series analysis, observed data