Dominant patterns of dryness/wetness variability in the Huang-Huai-Hai River Basin and its relationship with multiscale climate oscillations

Abstract

Abstract The understanding of dryness/wetness variability and its causes is vital for better water resources management, especially in precipitation deficit regions. This study assesses the behavior and potential risk of summer meteorological dryness/wetness, characterized by the Standardized Precipitation Evapotranspiration Index (SPEI), in the semiarid Huang-Huai-Hai (HHH) River Basin in northern China using Precipitation (P) and Potential Evapotranspiration (ET0) data of 186 stations during 1960–2017. The dominant patterns of dryness/wetness variability in the HHH river basin and the connections with atmospheric circulation and multiscale climate oscillations are also detected. The results show that (1) a general wetting trend can be detected in the HHH during summer using the rank-based nonparametric Mann-Kendall test, which is largely related to the increase in summer P and decrease in summer ET0, and the trends in summer SPEI based dryness/wetness are more sensitive to the changes in ET0 than in P; (2) the patterns of dryness/wetness variability over the HHH river basin can be dominantly represented by three leading Empirical Orthogonal Function (EOF) modes, which are strongly influenced by large-scale atmospheric circulations, such as the excessive (insufficient) precipitation, upward (downward) vertical motion and moisture convergence (divergence); and (3) the multiscale climate modes have significant effects on the dryness/wetness variability, which confirms the interactions between multiple low-frequency oscillations and the meteorological processes in the HHH river basin. The results of this study will be beneficial for water resources management, drought/flood forecast, and preparations for potential drought/flood hazards in the HHH River Basin and will also be a valuable reference for other arid and semiarid areas.