Modeling Impacts of Run-of-River Hydroelectric Projects

water power licenses in BC (image credit: IPP Watch, 2010)

Run-of-river (ROR) hydroelectric projects use the natural flow and gradient of a river to produce electricity. A portion of the river’s flow is diverted out-of-channel and transported downhill to a powerhouse, where the water turns turbines, generating electricity. The river water is subsequently returned to the channel downstream from the powerhouse, restoring natural stream flow. As a result of this process, a portion of the river channel between the intake structure and the outlet from the powerhouse, often stretching several kilometers, experiences reduced flow levels. How best to assess the impacts of reduced flow levels on fish habitat is a somewhat unresolved issue, but it is critical given climatic changes in precipitation patterns and tight field-monitoring budgets. With the emergence of ROR hydroelectric project development by independent power producers (IPPs) as a major component of BC’s energy policy (see map, source:, there is a growing need for effective and efficient methods to assess the instream flow requirements for fish species. Conventional instream habitat models (e.g. PHABSIM, RHYHABSIM, EVAH, etc.) have been used for quantifying the impacts of flow changes by linking traditional hydraulic engineering models to habitat preference curves of different fish species for water depth, velocity, and bed particle size. However, the application of these conventional models can be limited by the cost and expertise associated with field data collection. Dorian Turner, a REM graduate student from the Water Research Group, is working under the supervision of Dr. Randall Peterman and Mike Bradford (Department of Fisheries and Oceans) to determine whether or not generalized habitat models, which use simpler and more cost-effective stream descriptions, can be used to produce similar results to the conventional instream habitat models used in streams on the southwest coast of British Columbia. See also: Climate Change Impacts Research Consortium.