Page - 1061 - in Book of Full Papers - Symposium Hydro Engineering

Figure 3: Aerial photo of Ramsele dam and spillway (Norconsult, 2015). 2. RESULT OF SAFETY EVALUATIONS The Swedish Guidelines for Design Flood Determination, classify dams into two categories depending on the consequences of a dam failure (). Table 1: Classifications of dam failure consequences and corresponding design flood. Design flood category Class I Class II Dam failure consequence category Loss of human life, damage to vital infrastructure, etc. Property and infrastructure damage,. Hydrological modeling technique Extreme precipitation combined with heavy snowmelt and saturated soils Frequency analysis Return period, years > 10 000 >100 Both Långströmmen and Ramsele are classified as high-hazard dams, or Class I, implying that a 10 000 year flood must be safely passed. Not only does this signify that the floodwaters must be evacuated without exceeding the maximum design water level thereby jeopardizing the structural integrity of the embankment dams. It also means that the spillways must be designed with energy dissipators and 1061