Peace Project Water Use Plan - BC Hydro

Peace Project Water Use Plan
Annual Report: 2010
ToR Status: In January 2010 the CWR approved a resubmission of the
GMSWORKS#5 ToR with updated project implementation costs. The project
complies with the revised ToR; no further resubmission is anticipated at this time.
5.1.5.2 Contractor’s Report
Hydroelectric generation from the Peace River produces nearly a third of British
Columbia’s electricity through Gordon M. Shrum (GMS) power station at W.A.C
Bennett Dam and Peace Canyon Dam (PCN) 14 km downstream. Downstream of
PCN, seasonal flows have been normalized with a reduction in spring and summer
high flows and an increase in lower autumn and winter flows. Pre-regulation annual
maximum daily discharge downstream of PCN ranged from 1,640 to 8,810 m 3 /s with
an average of 6,165 m 3 /s. Post regulation annual maximum discharge averages
1,940 m 3 /s. GMS and PCN are power-peaking facilities that fluctuate water levels on
an hourly basis.
The variability in flow impacts side channel habitat and fish potentially through
mobilization or displacement of fish, fish stranding, channel isolation, or dewatering
that can lead to mortality from suffocation, predation, or freezing. Despite obstruction
and regulation, there are existing successful fish populations within the Peace River.
Two (2) other studies along the Peace River have concurrently been progressing:
1. GMSWORKS#3 Peace River Side Channel Restoration, where side channel
habitat along the Peace River have been identified and prioritized between
PCN and Pine River.
2. GMSWORKS#6 Peace River Mainstem Stage Discharge, where an additional
sixteen (16) bathymetric cross-sections were surveyed and five (5) pressure
transducers installed with 10-point stage discharge relationships developed.
The study presented in the following text (GMSWORKS#5) uses the data collected in
the other two (2) projects to develop, calibrate, validate, and apply a Mike11 onedimensional
numerical model for a 98 km long reach of the Peace River; extending
from six (6) kilometres downstream of the PCN to just downstream of Pine River.
Thus addressing a primary data gap identified in the summary and recommendations
of GMSWorks#3; the development of a hydraulic model to estimate water surface
elevations where side channel habitat is situated.
The model showed good correlation with the observed data (average R 2 of 0.89 to
0.95) with better correlation for flows greater than 800 m 3 /s. Maximum error between
modelled and observed water levels on average was 22 cm positive and 32 cm
negative. Modelled travel time of peak flows was between 8 and 12% greater than
observed over the 100 km long study reach.
From 33 identified side channels, the model results suggest:
1. at a PCN discharge of 283 m 3 /s, only 2 side channels are fully wetted and 4
partially wetted.
2. at PCN discharge of 500 m 3 /s, 5 side channels are fully wetted and 17
partially wetted.
3. at a discharge of 1,000 m 3 /s, 14 side channels are fully wetted and 29
partially wetted.
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