Abstract Salinization stands among the most prominent environmental hazards of the largest delta on Earth, the Bengal delta. It has significant impacts on the local societies and the economy. Using an unprecedented collection of in situ river salinity records over the Bengal delta, extending from the Hooghly estuary in the west to the Meghna estuary in the east, we report a sudden salinization of the central part of the delta that occurred in 2006–2007. This results in a sudden landward shift of the seasonal march of the salinity front by about 20 km, taking place in the pre-monsoon season. Such a regime shift was never reported before. We investigate the various drivers of this sudden change and identify three possible forcing factors: the decrease in Ganges freshwater discharge, the rise of sea level and the depletion of the groundwater level. These factors may act independently, or in concert. Given the threat of the ongoing climate change and its cohort of adverse effects expected in the course of the 21st century in the Bengal delta, our study contributes to set the observational basis for the development of the next generation of salinization modeling platforms.

中文翻译：

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孟加拉三角洲最近的盐分入侵：观察结果和可能的原因

摘要 盐碱化是地球上最大的三角洲孟加拉三角洲最突出的环境危害之一。它对当地社会和经济产生了重大影响。使用从西部的 Hooghly 河口延伸到东部的 Meghna 河口的孟加拉三角洲前所未有的原位河流盐度记录，我们报告了 2006-2007 年发生的三角洲中部突然盐碱化。这导致盐度锋的季节性行进突然向陆地移动约 20 公里，发生在季风前季节。以前从未报道过这种政权更替。我们调查了这种突然变化的各种驱动因素，并确定了三个可能的强迫因素：恒河淡水排放量减少、海平面上升和地下水位枯竭。这些因素可能独立起作用，也可能协同起作用。鉴于孟加拉三角洲持续的气候变化及其在 21 世纪期间预期的一系列不利影响的威胁，我们的研究有助于为下一代盐渍化建模平台的开发奠定观测基础。