<p>Descriptive statistics for the panel countries.</p>

This study examines how rainfall and groundwater recharge can help mitigate drought conditions, using the Standardized Precipitation Evapotranspiration Index (SPEI) as the drought indicator. It focuses on the top ten countries experiencing groundwater overexploitation and incorporates a global average perspective to provide deeper insights into these critical relationships. These insights are essential for informed policy-making and integrated decision-making, involving a range of stakeholders from local users to international policymakers on drought mitigation efforts from 1961 to 2022. The analysis employs the novel technique to estimate Dynamic Panel Threshold Regression (DPThR) model. The findings reveal that a 1-millimeter increase in rainfall improves the SPEI by 0.003 units, thereby reducing drought likelihood. The threshold for mitigating drought effects is identified at 614.41 millimeters of annual rainfall, with Pakistan, Iran, and Saudi Arabia being the most at-risk countries when rainfall falls below this level. Conversely, a one-standard-deviation increase in groundwater recharge enhances the SPEI by 5.06 units, indicating a substantial reduction in drought incidence. The threshold for mitigating drought effects is identified at –0.0039 standard deviations, with China, Iran, Mexico, Pakistan, Saudi Arabia, Turkey, and the United States being the most drought-prone when recharge falls below this level. Furthermore, it was found that temperature exerts a consistently negative and highly significant effect, indicating that warming intensifies drought through evapotranspiration and soil moisture depletion. While CO2 emissions show no significant direct impact. Moreover, the study identifies unidirectional causality running from rainfall, groundwater recharge, temperature, and CO2 emissions, reinforcing the dominance of hydro-climatic forces in driving drought variability. Policy recommendations include advancing artificial rainfall, enhancing groundwater recharge, and maintaining country-specific water use thresholds to reduce drought risk and strengthen water and climate resilience in overexploited regions.本研究以标准化降水蒸散指数（Standardized Precipitation Evapotranspiration Index，SPEI）作为干旱表征指标，探究降雨与地下水补给对干旱状况的缓解作用。研究聚焦于地下水超采程度排名前十的国家，并结合全球平均视角，以深化对上述关键关联的认知。此类认知对于制定科学决策、开展综合施策至关重要，研究覆盖1961年至2022年期间的干旱缓解相关工作，涉及从本地用水者到国际政策制定者的各类利益相关方。本分析采用新颖的动态面板门槛回归（Dynamic Panel Threshold Regression，DPThR）模型开展估算。研究结果显示，降雨量每增加1毫米，可使SPEI提升0.003个单位，从而降低干旱发生概率。研究确定了缓解干旱效应的年度降雨量阈值为614.41毫米，当降雨量低于该阈值时，巴基斯坦、伊朗与沙特阿拉伯为受干旱风险影响最严重的国家。反之，地下水补给量每增加一个标准差，可使SPEI提升5.06个单位，表明干旱发生概率大幅降低。研究确定的缓解干旱效应的地下水补给阈值为-0.0039个标准差，当补给量低于该阈值时，中国、伊朗、墨西哥、巴基斯坦、沙特阿拉伯、土耳其与美国为干旱高发国家。此外，研究发现温度始终呈现显著的负向影响，表明气候变暖通过蒸散作用与土壤水分耗竭加剧干旱。而二氧化碳排放量未表现出显著的直接影响。进一步而言，本研究证实降雨、地下水补给、温度与二氧化碳排放量均存在单向因果关系，进一步印证了水文气候因素在驱动干旱变异性中的主导地位。政策建议包括推进人工降雨、强化地下水补给，以及制定符合各国国情的用水阈值，以降低超采地区的干旱风险，提升区域水安全与气候韧性。