Climate change and rapid socioeconomic development have exacerbated the damage caused by hydrological droughts. To ensure effective drought defense and infrastructure development, it is essential to investigate variations in hydrological droughts. The primary objective of this study is to reconstruct the natural streamflow by using Soil and Water Assessment Tool (SWAT) hydrological modeling. The hydrological drought at different time scales (1, 3, 6, and 12 months) were measured using the streamflow drought index (SDI). The statistical parameters, including Nash–Sutcliffe Efficiency and the Coefficient of Determination, which yielded values of 0.84 and 0.82 during the calibration period and 0.78 and 0.76 during the validation period, respectively, showed a satisfactory SWAT model performance. Additionally, the Pettit test was used to identify a change point in streamflow within the 1991–2015 timeframe, leading to the division of the study period into two distinct phases: an undisturbed period (1991–1998) and a disturbed period (1999–2015). The SDI index‐based analysis revealed 9.39% moderate drought and 3.13% severe drought during the undisturbed period, while 11.76% moderate drought and 7.35% severe drought may happen due to the human influences that occurred in the disturbed period. These findings enhance the understanding of the hydrological drought variations in the Soan River basin for optimizing the water resources management system and effectively preventing and mitigating drought‐related damages.

中文翻译：

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巴基斯坦索安河流域自然水流重建和水文干旱量化

气候变化和社会经济快速发展加剧了水文干旱造成的损害。为了确保有效的干旱防御和基础设施发展，有必要调查水文干旱的变化。本研究的主要目的是利用土壤和水评估工具（SWAT）水文模型重建自然水流。使用径流干旱指数（SDI）测量不同时间尺度（1、3、6和12个月）的水文干旱。统计参数，包括纳什-萨特克利夫效率和决定系数，在校准期间分别产生 0.84 和 0.82，在验证期间分别产生 0.78 和 0.76，显示出令人满意的 SWAT 模型性能。此外，佩蒂特检验用于确定1991-2015年时间范围内水流的变化点，从而将研究时期分为两个不同的阶段：未受干扰时期（1991-1998年）和受干扰时期（1999-2015年） ）。基于SDI指数的分析显示，未受干扰期间，9.39%的中度干旱和3.13%的重度干旱，而11.76%的中度干旱和7.35%的重度干旱可能是由于受干扰期间发生的人类影响而发生的。这些发现增强了对索安河流域水文干旱变化的认识，有助于优化水资源管理系统，有效预防和减轻干旱造成的损害。