Innovations & dam safety | Under Swiss supervision Swiss dam safety regulations are evolving to meet current and future challenges
Right: Swiss dam safety regulations are evolving
MOST OF SWITZERLAND’S LARGE dams were built from 1940-70, mainly for the purpose of hydropower. As Schwager et al discuss in their paper on ‘Swiss Dam Safety Regulation”, in recent decades an increasing number of smaller dams have also been built to protect against natural hazards such as flood and debris flow. However, as Swiss dam safety regulations were developed for larger dams serving the hydropower industry, various adaptations are now need for these natural hazard protection dams (NHPD). Under Swiss law a retaining dam structure is any
Below: Investigations are underway into the impact of alkali aggregate reaction on Swiss dams
installation designed to retain water, debris, sediment, ice, or snow – whether on a permanent or temporary basis. About 50 NHPDs have been built across Switzerland since 2000 and they have been subjected to the same safety directives as water retaining facilities in case they fulfil the size criteria, or have a particular risk potential in case of collapse of the retaining facility.
As the authors highlight in their paper there are fundamental differences between NHPDs and conventional water retaining ones. These include that NHPDs are built for civil and infrastructure protection when conventional ones are used mainly for hydropower production. NHPD reservoirs are seldom impounded and when they are, only for hours or days (or in the case of debris and snow possibly weeks to months), whereas conventional ones are impounded for most of the year with water. This potentially leads to ‘unproportionate safety
requirements’ for NHPDs and there has been a call to revisit and, where appropriate, add or modify safety regulations for this specific type of smaller dams. Aspects that require further research and potentially updates to Swiss dam safety regulations include: Specific load cases and load combinations for NHPDs, such as avalanche impact forces.
16 | March 2024 |
www.waterpowermagazine.com
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