Water Stewardship Information Sources
| Citation | Schaefer, MG et al. 2012. Development of hydrologic hazard curves for assessing hydrologic risks for Strathcona, Ladore Falls and John Hart Dams on the Campbell River, BC. Prepared for BC Hydro. |
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| Organization | BC Hydro |
| URL | http://www.mgsengr.com/damsafetyfiles/ASDSOCampbellRiverSEFMReport_07252012.pdf |
| Abstract/Description or Keywords | The Campbell River hydroelectric system (BCHydro) is comprised of the Strathcona, Ladore Falls and John Hart Dams on the Campbell River on Vancouver Island, BC. In 2003, a new study of Probable Maximum Precipitation (PMP) was completed that increased the PMP estimate by 33% and required re-analysis of the Probable Maximum Flood (PMF). Reservoir routing of the updated PMF indicated overtopping of all three projects. Interim measures were taken to reduce the likelihood of dam overtopping from an extreme flood at Strathcona Dam, which is a 53-m high earthfill structure that impounds 900-million m3 (723,000 acre-feet) at normal pool. A probabilistic flood study was initiated to estimate the likelihood of various flood magnitudes for use in assessing hydrologic risk at the projects for various potential failure modes. A stochastic flood model was developed for use in developing magnitude-frequency estimates for floods, particularly extreme floods. The stochastic flood model utilized a deterministic flood computational model (UBC Watershed model) and treated the hydrometeorological input parameters as variables instead of fixed values. Monte Carlo sampling procedures were used to allow the climatic and storm-related input parameters to vary in accordance with that observed in nature. Hydrometeorological inputs that were treated as variables included: seasonality of storm occurrence; magnitude of extreme storms, temporal and spatial distribution of storms; temporal temperature pattern during the storm; 1000-mb and freezing level temperatures; hydrologic model antecedent conditions (snowpack, soil moisture, initial streamflow), and initial reservoir storage. Sixty-thousand computer simulations were conducted to develop magnitude-frequency relationships for the flood characteristics of peak discharge, maximum reservoir release, runoff volume, and maximum reservoir level. The AEP for flood waters reaching the top of the lock blocks on Strathcona Dam (226.30 m) was estimated to be 1:5,500,000 and the annual probability of flood waters reaching the top of the impervious core (224.60 m) was estimated to be 1:34,000. The annual probability of overtopping at Ladore Dam (179.35 m) was estimated to be 1:960,000. The annual probability of overtopping of John Hart Dam (141.73m) was estimated to be 1:1,400,000 and overtopping of the impervious core, slurry wall and sheet piles (140.50m) was estimated to be 1:65,000. |
| Information Type | report |
| Regional Watershed | Vancouver Island North |
| Sub-watershed if known | Campbell River |
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| Project status | complete |
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