Age, climate and economic disparities drive the current state of global dam safety

Dams are essential for flood protection, water resources management, energy generation and storage and food production. However, the consequences of their failure can be catastrophic, as demonstrated by recent examples. Here this study revisits dam failures worldwide since 1900, analysing key factors driving the failure risk, profiling current dam safety and providing an outlook to the near future. Similar to previous analyses (1970s to 2010s), we observe a strong infant mortality, which remains especially important for the development of new embankment dams, while recent concrete dams have become more resilient. In contrast, hazard signals related to ageing remain yet less apparent, contrary to common belief. Nevertheless, given their abundance, we expect decades-old dams to be prevalent in future failure statistics-especially for embankment dams of height between 15 and 70 m built in the second half of the last century. This highlights the relevance of investments in monitoring, maintenance and uprating, which, if ignored, could become a substantial liability and a major vulnerability, especially in the context of increased flooding frequency. We uncover a trend of increased failure rates of newly constructed dams in low-income regions, which coincides with areas where a substantial hydropower potential remains untapped. This is especially intensified in monsoon-dominated climates, whereas the pattern of construction and failures is more homogeneous across other major climatic regions. Our statistical analysis suggests that 23 (95% confidence interval 14-33) large dam failures are to be expected worldwide in the near future (2023-2035), with currently similar to 4.4% of large dams having a probability of failure larger than 1/10,000. Contrarily, 85% of large dams are at least twice as safe as this threshold, commonly embraced in policy. These findings can support the targeted allocation of limited resources for the future-proofing of infrastructure, thereby contributing to water, food and energy security.