Due to the effects of global climate change on duration, frequency and number of drought events, the occurrence of prolonged droughts, referred to as “megadroughts” (lasting for two decades or longer) will become more probable in the future. Thus, it is crucial for countries especially in arid and semi-arid regions of the world to develop appropriate preparedness plans for megadrought risk management. Since groundwater is the key water resource in these regions, it is important to reliably quantify the maximum sustainable extraction to ensure a sufficient groundwater reserve, i.e. the Strategic Groundwater Reserve, for a probable future megadrought event. For this purpose, a new concept of Probable Maximum Drought is proposed in this study, based on the concept of Probable Maximum Flood. As the spillways of large dams are designed based on the Probable Maximum Flood to minimize the probability of failure and the associated casualties and damages, the Probable Maximum Drought concept is proposed to estimate Strategic Groundwater Reserves to limit the consequences of prolonged droughts, including damage and threats to societal stability. This will allow water resources managers and policymakers to develop appropriate strategies to adapt and restrict development plans of a given region based on a sustainable megadrought risk management.

由于全球气候变化对干旱事件的持续时间，频率和次数的影响，未来将有可能发生称为“大干旱”（持续数十年或更长时间）的长期干旱。因此，对于世界特别是干旱和半干旱地区的国家而言，制定适当的巨灾风险管理准备计划至关重要。由于地下水是这些地区的关键水资源，因此重要的是可靠地量化最大的可持续开采量，以确保有足够的地下水储备，即战略地下水储备，以应对未来可能发生的特大干旱事件。为此，本研究基于“可能的最大洪水”概念提出了一个“可能的最大干旱”新概念。由于大型水坝的溢洪道是根据“可能的最大洪水”设计的，目的是最大程度地减少失败的可能性以及相关的人员伤亡和破坏，因此建议“可能的最大干旱”概念来估算战略地下水储备，以限制长期干旱的后果，包括破坏和对社会稳定的威胁。这将使水资源管理者和政策制定者能够基于可持续的大干旱风险管理，制定适当的策略来适应和限制特定地区的发展计划。