【摘要】 干旱级联传播严重制约区域水资源可持续利用，但目前仍缺乏长链式干旱传播阈值动态演变规律的定量刻画，且阈值变化的多过程耦合驱动机制尚未明晰。本文以蒙古高原为研究区域，集成标准化降水指数（SPI）、标准化径流指数（SRI）和标准化土壤水指数（SSI）、游程理论、Copula函数模型与机器学习方法，系统解析了1982—2021年干旱级联传播阈值时空动态及其驱动因子。结果表明：1982—2021年研究区超过30%区域的SPI、SRI与SSI均变干，其变干速率分别为-0.25/10a、-0.19/10a和-0.34/10a。SPI及SRI呈现“高频次—短历时—低强度”特征，SSI呈现“低频次—长历时—高强度”特征。干旱传播遵循“气象干旱→水文干旱→土壤水干旱”级联路径，平均传播时间分别为2个月和9个月。干旱级联传播概率呈现“等级正相关、强度负相关、路径衰减性”的三重特征。蒙古高原山区及林地的传播阈值较低，耐旱性较强，中部荒漠—典型草原过渡带传播阈值较高，容易引发级联效应，呈现“边缘低敏感—内部高敏感”的特征。分别有60%和49%区域的SPI→SRI和SRI→SSI传播阈值呈上升趋势。此外，降水主导SPI→SRI传播（贡献率44%），土壤含水量（贡献率60%）成为SRI→SSI传播的关键瓶颈，NDVI、潜在蒸散发与温度协同调控边缘过渡带级联风险。研究结果可为干旱半干旱区级联干旱精准预警提供依据，同时为降低干旱传播对生态系统的负面影响，实现区域生态及农牧业可持续发展提供理论参考。更多还原

【Abstract】 Drought cascade propagation critically constrains sustainable water resource utilization, yet quantitative characterization of dynamic drought propagation thresholds and their multi-process drivers remains limited. This study integrates meteorological(SPI), hydrological(SRI), and soil moisture drought indices(SSI), run theory, Copula models, and machine learning to analyze spatiotemporal patterns and drivers of drought propagation thresholds in the Mongolian Plateau(1982-2021). The results show that over 30% of the study region exhibited drying trends for SPI(-0.25/10a), SRI(-0.19/10a), and SSI(-0.34/10a), with SPI/SRI showing "high frequency, short duration, low intensity" features versus SSI’s "low frequency, long duration, high intensity" pattern. Droughts propagate sequentially as "meteorological drought→ hydrological drought→soil moisture drought", averaging 2 and 9.01 months between stages. The probability of drought cascade propagation showed the triple characteristics of "positive correlation of rank, negative correlation of intensity and attenuation of path". Propagation thresholds are lower in mountainous forests(drought-resistant) but higher in central desert-grassland transition zones(prone to cascading effects), forming a pattern of core vulnerability and edge insensitivity. Notably, 59.58% and 49.20% of areas show rising SPI→SRI and SRI→SSI propagation thresholds, respectively. In addition, precipitation dominated the SPI→SRI propagation(contribution rate 43.56%), soil moisture content(contribution rate 60.14%) became the key bottleneck of SRI→SSI propagation, and NDVI, potential evapotranspiration and temperature synergistically regulated the cascade risk of the marginal transition zone. The results of the study can provide a basis for precise early warning of cascading drought in arid and semi-arid zones, as well as theoretical references to reduce the negative impacts of drought propagation on ecosystems and realize the sustainable development of regional ecology and agriculture and animal husbandry.更多还原