Scientific Reports (Nov 2024)
Analysis of the spatial and temporal evolution of drought in Henan based on a nonlinear composite drought index
Abstract
Abstract It is of practical significance to provide a reference for drought mitigation and water resource enhancement planning in the Henan Province region and to analyze the spatial and temporal evolution characteristics of meteorological agricultural drought in the region. In this study, a multivariate (precipitation, potential evapotranspiration, soil moisture and normalized vegetation index) composite drought index CCDI was constructed based on the D Vine copula model, and the correlations between the CCDI and the standardized precipitation evapotranspiration index (SPEI) and between the CCDI and the standardized soil moisture index (SSI) were analyzed. The ability of the CCDI to evaluate meteorological agricultural drought was assessed, and typical drought events were selected for validation. The spatial and temporal evolution of drought in the Henan region from 1982 to 2022 was characterized using linear trends, M–K mutability tests, and drought centers of gravity, and future trends were analyzed using the Hurst index. The results show that (1) the CCDI correlates well with the SPEI and SSI (P < 0.01) and is able to characterize both meteorological and agricultural drought conditions in a better integrated way. (2) The fluctuation frequencies of the CCDI were obviously different at different time scales, indicating the different sensitivities of drought time scales to precipitation, potential evapotranspiration, soil moisture and the NDVI. All four seasons showed increasing trends at different rates. (3) During the study period of 1982–2022, the frequency of drought in Henan Province was mainly in the range of 21.95%-41.46%, and the intensity of drought occurrence was mainly dominated by light to moderate drought. (4) Based on the migration characteristics of the center of gravity of drought determined by ArcGIS, the center of gravity of drought during the study period is mostly concentrated in several cities in the central part of Henan, and the migration trajectory is mostly in the north‒south north–south direction, which is in line with the characteristics of the distribution of the data expressed by the standard deviation ellipse. (5) To analyze future drought trends in Henan, the mean values of the Hurst index in spring, summer, autumn and winter were 0.578, 0.766, 0.62 and 0.596, respectively, all of which showed persistent trends, while spring and winter Most areas may still have a dry trend in the future, the future dry trend in summer is mainly concentrated in the area around Henan, and the wet trend is distributed in the central-eastern part of the country and individual areas in the north and south. In the fall, most of the areas are wet trend, and individual areas have arid trend.The comprehensive drought index constructed in this paper can provide a new reference for drought prevention and drought relief in Henan Province.
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