Thunder Storm Impacts on Dam Safety
Hamid Goharnejad (Meco)

In July 2023, Nova Scotia experienced a two-day summer storm characterized by intermittent short-duration, high intensity rainfall events dubbed by Environment Canada as a ’“Thunder Train’”. The entire event, lasting only about 24-hours, was an impressive thunder and lightning show with a mixture of 3-hour, 6-hour and 12-hour individual events with annual exceedance probabilities AEP of up to 100 years. The aggregate rainfall totals of up to 300mm resulted in significant flooding and infrastructure damage throughout central Nova Scotia, at least one declared dam emergency and some loss of life unrelated to dam safety. The study will suggest a typical storm pattern from the July 2023 storm event that can be a basis for future dam safety assessments in the region. Dams are typically designed for 24-hour to 72-hour storm events that may not capture the consequences of short duration, high-intensity inflow events. The purpose is to evaluate the impact on storage and routing of watersheds in municipal areas that are formed by dams that may have a different risk profile when subjected to summer storm events.