Abstract：
Droughts frequently occurring in India have significant societal, economic, and environmental effects. The lack of direct measurements of groundwater in location and time hinders quantitative methods to analyse the intricate nature of groundwater drought. This work used the datasets derived from the Gravity and Climate Experiment (GRACE and GRACE-FO) and Global Land Data Assimilation System (GLDAS) to extensively analyse Groundwater Storage changes in the Lower Gangetic Basin (LGB) using unique hydrological parameters between the years 2003 and 2022. The analysis highlights that the GRACE-derived terrestrial water storage anomaly in the LGB decreased significantly (-12.12 mm/yr), and the amount of Groundwater Storage Anomaly (GWSA) decreased similarly (-10.80 mm/yr), while in the GRACE-FO period, a positive trend has been noticed in TWSA (33.96 mm/yr) and GWSA (64.8 mm/yr) respectively. A drought indicator called the GRACE-derived groundwater drought index (GGDI) has been computed for the entire LGB region. A traditional drought study viz. Standardised Precipitation Index (SPI) was performed over LGB to justify the results of the GGDI. The results from GGDI study effectively matched the periods of significant drought occurrences with the 12-month SPI time series. From the GGDI, this study examined groundwater drought\'s spatial distribution, temporal evolution, and trend (Modified Mann Kendall trend) aspects. According to research findings, the LGB experienced three major drought periods between 2009-2010, 2019 (moderate), and 2015-2016 (severe). The study offers reliable quantitative data on the evolution of GRACE-derived groundwater drought, which may add a new perspective to additional drought research in the densely populated study area, which depends majorly on agriculture, livestock and less skilled water-intensive industries such as leather and textile industries in a sub-tropical climate. This paradigm incorporates changes in groundwater resources caused by human activities and climate change, paving the way for measuring progress towards sustainable use and water security.
摘要：
印度经常发生的干旱具有重要的社会性，经济,和环境影响。缺乏直接测量地下水的位置和时间阻碍了定量方法来分析地下水干旱的复杂性质。这项工作使用了重力和气候实验（GRACE和GRACE-FO）和全球土地数据同化系统（GLDAS）得出的数据集，使用独特的水文参数广泛分析了下恒河盆地（LGB）的地下水储量变化。2003年至2022年。分析结果表明，LGB中GRACE衍生的陆地储水异常显着下降（-12.12mm/yr），地下水存储异常（GWSA）的数量也类似地减少（-10.80毫米/年），而在GRACE-FO时期,TWSA（33.96mm/yr）和GWSA（64.8mm/yr）分别出现了积极趋势。已计算出整个LGB地区的干旱指标，称为GRACE衍生的地下水干旱指数（GGDI）。传统的干旱研究。在LGB上执行标准化的沉淀指数(SPI)以证明GGDI的结果。GGDI研究的结果有效地将重大干旱发生的时期与12个月的SPI时间序列相匹配。从GGDI，这项研究考察了地下水干旱的空间分布，时间演变,和趋势(修正曼恩·肯德尔趋势)方面。根据研究结果,LGB经历了2009-2010年、2019年的三个主要干旱时期(中度)，2015-2016年（严重）。该研究提供了有关GRACE衍生的地下水干旱演变的可靠定量数据，这可能为人口稠密的研究区域的其他干旱研究增加新的视角，这主要取决于农业，在亚热带气候中，畜牧业和技术较低的水密集型产业，如皮革和纺织业。这种模式包含了人类活动和气候变化引起的地下水资源的变化，为衡量可持续利用和水安全方面的进展铺平道路。
