在气候变化与高强度人类活动交互作用下,吉泰盆地水文干旱演变机制呈现显著阶段性差异。基于1959—2023年数据,通过Pettitt检验划分基准期、过渡期和变化期,结合改进的两参数月水量平衡模型,剖析不同阶段干旱特征及多种驱动要素的差异化影响。结果表明:蜀水、乌江、同江典型流域在1980年、2008年前后产流机制发生转折,径流系数α 在过渡期显著增加后,变化期回落。过渡期干旱烈度和历时较基准期明显下降,变化期则反弹,3个典型流域平均干旱烈度较过渡期分别增加46.2%、26.9%和25.9%。夏秋高温少雨是吉泰盆地水文干旱的重要驱动因素,其与干旱烈度的敏感性较强,期间降水每减少10%,干旱烈度值增加0.14~0.23,存在边际递减效应。然而,与基准期相比,变化期人类活动影响占主导作用,其导致径流深和干旱烈度变化幅度超过气候变化因素。研究构建的多阶段驱动因子量化方法,揭示了不同要素对水文干旱烈度的非线性调控作用,可为吉泰盆地干旱预警及长期趋势预测提供参考。

[Objective] This study aims to investigate the differentiated effects of various driving factors on the stage-specific characteristics of hydrological drought in the Jitai Basin under the influence of climate change and intensive human activities. [Methods] We collected meteorological and hydrological data from 1959 to 2023 from three typical watersheds (the Shushui, Wujiang, and Tongjiang Rivers) in the Jitai Basin, and adopted the Pettitt test to divide the study period into a baseline period, a transition period, and a change period. By using the improved two-parameter monthly water balance model, we analyzed the drought characteristics and the quantitative effects of driving factors in each stage, and clarified the dominant role of different driving factors as well as their nonlinear regulation mechanisms. [Results] 1) The runoff generation mechanisms of the three typical watersheds shifted around 1980 and 2008. Specifically, in baseline period (1959-1980), the underlying surface conditions of the watersheds were relatively stable, hydrological processes were dominated by natural climate drivers, and runoff variations were directly controlled by the precipitation-evaporation balance, with no obvious disturbance from human activities. In transition period (1981-2008 ), the intensifying regional human activities began to alter the original runoff generation mechanisms of the watersheds. In the change period (2009-2023), underlying surface modification and water conservancy project regulation became dominant factors. The runoff coefficient α increased significantly in transition period and then declined in the change period, which also indicated that the regulatory intensity of human activities on runoff exceeded natural fluctuations. In terms of drought characteristic variations, drought severity and duration decreased notably in the transition period compared with the baseline period, but rebounded in the change period; the average drought severity of the three typical watersheds increased by 46.2%, 26.9% and 25.9% respectively relative to the transition period. 2) By introducing a regulating coefficient of parameter C during wet and dry periods, the improved two-parameter monthly water balance model effectively improved the overall simulation accuracy of runoff series, especially for low-flow and drought months. The Nash-Sutcliffe efficiency coefficient (NSE) was higher than 0.7 and the correlation coefficient R exceeded 0.85 in both the baseline and transition periods, with the water balance error controlled within ±1%. In the change period, the measured runoff series was heavily disturbed by human activities, which increased the difficulty of simulating monthly-scale runoff series. Parameter calibration results showed that the value of C for each typical watershed in transition period was lower than that in baseline period, but rebounded in the change period, reflecting regular variations in the precipitation-evaporation relationship of the watersheds across different stages. High temperature and low rainfall in summer and autumn were critical driving factors of hydrological drought in the Jitai Basin, with strong sensitivity to drought severity. A 10% reduction in precipitation during this period led to an increase of 0.14-0.23 in drought severity, accompanied by a marginally diminishing effect. Nevertheless, compared with the baseline period, human activities played a dominant role in the change period, causing greater variations in runoff depth and drought severity than climate change factors. [Conclusion] The multi-stage quantitative method for driving factors constructed in this study reveals the nonlinear regulatory effects of climate change and human activities on hydrological drought severity in the Jitai Basin at different stages, clarifies the influence intensity, sensitivity and stage characteristics of each driving factor, and identifies the nonlinear regulation of these factors on drought severity.