Groundwater is the replenishable and dynamic resources on the earth. Understanding the sustainability of water management is, therefore, the crucial factor in faring about agriculture, economy and environmental conditions. This study investigated the sustainability of large-scale groundwater-based irrigation by identifying the trend in groundwater depth (GWD) and explored the driving factors to characterize the identified trends in the lower Ganga River basin (LGRB) in India with an area of 195,601 km2. Trends were identified in the in situ observation groundwater data (total wells = 527) by applying innovative trend analysis (ITA), Mann–Kendall (MK) test or modified MK (mMK) and Sen’s slope estimator. The obtained results of all the methods confirmed that GWD in most of the studied wells had an increasing tendency in LGRB during 1996–2017. ITA showed that almost 85.39%, 62.23%, 85.39% and 57.12% wells for pre-monsoon, monsoon, post-monsoon and winter seasons, respectively, showed increasing trends. The rapidly increasing trend (slope: 5.22–136.33 cm/year) in monsoon season indicates shallow groundwater resource depletion, and groundwater abstraction exceeds the groundwater recharge. Findings also revealed that shallow pumps would not be functioning in the future for large-scale irrigation since shallow water is becoming scarce due to increasing water depth. In spite of irrigated areas continued almost the same (1997–2014), decreasing rainfall along with unplanned development of water resources is primarily identified as the main driving force for groundwater depletion at a large scale. Planned water management is urgent for ensuring sustainable irrigation water management.

中文翻译：

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探索印度恒河下游流域大规模不可持续的地下水开发用于灌溉的驱动力

地下水是地球上可补充的动态资源。因此，了解水资源管理的可持续性是影响农业、经济和环境条件的关键因素。本研究通过确定地下水深度 (GWD) 的趋势来调查大规模地下水灌溉的可持续性，并探讨了表征印度恒河下游流域 (LGRB) 已确定趋势的驱动因素，面积为 195,601 平方公里. 通过应用创新趋势分析 (ITA)、Mann-Kendall (MK) 检验或修正的 MK (mMK) 和 Sen 斜率估计器，在原位观测地下水数据（总井数 = 527）中确定了趋势。所有方法所得结果证实，1996-2017年期间，大多数研究井的GWD在LGRB中都有增加的趋势。ITA 显示，季风前、季风、季风后和冬季的近 85.39%、62.23%、85.39% 和 57.12% 的井分别呈现增加趋势。季风季节迅速增加的趋势（坡度：5.22-136.33 cm/年）表明浅层地下水资源枯竭，地下水抽取量超过地下水补给量。调查结果还表明，由于水深增加，浅水变得稀缺，因此浅水泵在未来无法用于大规模灌溉。尽管灌溉面积几乎保持不变（1997-2014），但降雨量减少和水资源的无计划开发主要被确定为地下水大规模枯竭的主要驱动力。有计划的水管理对于确保可持续的灌溉水管理至关重要。