Key points are not available for this paper at this time.
Study region: Jiangsu Province, eastern China, characterized by a humid monsoon climate, dense river networks, intensive water use, and strong interactions among precipitation, runoff, and groundwater. Study focus: This study develops a climate-informed Nonstationary Trivariate Standardized Drought Index (NTSDI) to characterize compound drought dynamics under changing hydroclimatic conditions. Precipitation, surface runoff, and groundwater are integrated within a unified probabilistic framework. Large-scale climate indices are incorporated as explanatory variables to account for climate-driven nonstationarity. Nonstationary marginal distributions are modeled using Generalized Additive Models for Location, Scale, and Shape, while a time-varying D-vine copula is applied to capture evolving multivariate dependence structures. New hydrological insights for the region: Results reveal a significant hydroclimatic regime shift around 2003 across precipitation, surface runoff, and subsurface runoff. Compared with the pre-change period, precipitation decreased by 8.78%, surface runoff by 20.98%, and subsurface runoff by 36.89%, indicating amplified drought propagation from atmospheric input to subsurface hydrological response. The NTSDI effectively captures compound drought evolution and delayed subsurface hydrological responses, providing a more robust basis for regional drought monitoring than conventional indices. By explicitly accounting for climate-driven nonstationarity and multivariate dependence, it offers valuable support for drought risk assessment and adaptive water resources management in highly dynamic hydroclimatic regions such as Jiangsu Province.
Yu et al. (Wed,) studied this question.