Decoding the hydroclimatic variability in the Minjiang River, Southeast China: The influence of ENSO, PDO, AO, and anthropogenic regulations

Study region: Minjiang River (MJR), Southeast (SE) China Study focus: The hydrological response mechanisms of rivers to coupled climatic and anthropogenic influences remain insufficiently understood. To address this gap, we analyzed the hydrological and climatic variations of the MJR using a suite of approaches, including the Bayesian Estimator of Abrupt Change, Seasonality and Trend (BEAST), Double Mass Curve (DMC), Continuous Wavelet Transform (CWT), Wavelet Coherence (WTC), and Multiscale Wavelet-Bayesian Coupled Regression (MWBCR). New hydrologic Insights: The results revealed that sediment load exhibited an interannual (7-a, ENSO-like) periodicity, with a significant reduction due to damming prior to 1993, whereas its decadal (PDO-like) signal was obscured by intensive human interventions. Precipitation and water discharge fluctuated within a relatively narrow range but showed distinct interannual and decadal periodicities, reflecting the combined influences of the Arctic Oscillation (AO), ENSO, and PDO. Since the 1990s, precipitation variability has been strongly associated with frequent AOI shifts. Moreover, higher precipitation variability was closely linked to in-phase La Niña–cold PDO events, which enhanced typhoon landfalls in SE China. In contrast, out-of-phase ENSO–PDO conditions corresponded to relatively drier and less variable hydroclimatic conditions, characterized by reduced precipitation and fewer typhoon occurrences.