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<p>The Extreme-point Symmetric Mode Decomposition (ESMD) method was employed to analyze runoff evolution in the Xijiang River Basin, enabling the identification of multi-scale periodicities, nonlinear trends, and multiple abrupt changes. Seven representative hydrological stations covering the upper, middle, and lower reaches, including major tributaries, were selected for the analysis. The ESMD results were validated through comparison with conventional statistical methods, and the detected abrupt change points were subsequently used to delineate distinct analysis periods. The contributions of Climate Change (CC) and Human Activities (HAs) to runoff variations were quantified using the Double Mass Curve (DMC) and the Slope Changing Ratio of Cumulative Quantity (SCRCQ) approaches. The results indicated that runoff evolution in the upper and middle reaches was predominantly influenced by HAs. The most conservative estimate attributed approximately 56% of the total variation to HAs, and a base period sensitivity test (± 5 years) suggested a plausible lower bound range of 52–60%. At the remaining upper–middle stations, HAs contributions were substantially higher (≥ 88%). This dominance was mainly associated with intensive cascade reservoir construction. In contrast, CC played a dominant role in the lower reaches and tributaries, mainly associated with precipitation variability and tributary inflows. Compared with conventional methods, the ESMD method exhibited greater sensitivity in detecting nonlinear trends and abrupt changes, demonstrating strong adaptability to complex hydrological processes. These findings provide a scientific basis for adaptive and region-specific water management across the basin. In particular, optimizing cascade reservoir operations in the upper and middle reaches was found to be crucial for enhancing the coordination of flood control, ecological flow maintenance, and drought mitigation. Conversely, in the lower reaches, emphasis should be placed on improving ecological flow regulation and water allocation to mitigate precipitation uncertainty and inflow variability.</p>

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Runoff evolution and driving mechanisms in the Xijiang River basin under the changing environment: an ESMD-based analysis

  • 期刊论文

  • 发表日期：

    2026年4月1日

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  • Jiqing Li,
  • Xinyi Deng,
  • Peng Zhang

摘要

The Extreme-point Symmetric Mode Decomposition (ESMD) method was employed to analyze runoff evolution in the Xijiang River Basin, enabling the identification of multi-scale periodicities, nonlinear trends, and multiple abrupt changes. Seven representative hydrological stations covering the upper, middle, and lower reaches, including major tributaries, were selected for the analysis. The ESMD results were validated through comparison with conventional statistical methods, and the detected abrupt change points were subsequently used to delineate distinct analysis periods. The contributions of Climate Change (CC) and Human Activities (HAs) to runoff variations were quantified using the Double Mass Curve (DMC) and the Slope Changing Ratio of Cumulative Quantity (SCRCQ) approaches. The results indicated that runoff evolution in the upper and middle reaches was predominantly influenced by HAs. The most conservative estimate attributed approximately 56% of the total variation to HAs, and a base period sensitivity test (± 5 years) suggested a plausible lower bound range of 52–60%. At the remaining upper–middle stations, HAs contributions were substantially higher (≥ 88%). This dominance was mainly associated with intensive cascade reservoir construction. In contrast, CC played a dominant role in the lower reaches and tributaries, mainly associated with precipitation variability and tributary inflows. Compared with conventional methods, the ESMD method exhibited greater sensitivity in detecting nonlinear trends and abrupt changes, demonstrating strong adaptability to complex hydrological processes. These findings provide a scientific basis for adaptive and region-specific water management across the basin. In particular, optimizing cascade reservoir operations in the upper and middle reaches was found to be crucial for enhancing the coordination of flood control, ecological flow maintenance, and drought mitigation. Conversely, in the lower reaches, emphasis should be placed on improving ecological flow regulation and water allocation to mitigate precipitation uncertainty and inflow variability.