Water Stewardship Information Sources

Citation Northwest Hydraulic Consultants Ltd. 2010. Cheakamus River Water Use Plan, Monitoring Channel Morphology in Cheakamus River, Implementation Year 2, Study Period: April 2009-April 2010. Prepared for BC Hydro.
Organization BC Hydro
URL https://www.bchydro.com/content/dam/hydro/medialib/internet/documents/planning_regulatory/wup/lower_mainland/2010q4/cmsmon-8_yr2_2010-05-14.pdf
Abstract/Description or Keywords Hydrometric monitoring has continued at three locations along the Cheakamus River
system between Daisy Lake Dam and the Cheekye confluence since February 2008:
• Cheakamus River above Chance Creek (Forest Service road bridge below Daisy Lake
Dam), hereinafter referred to as ‘Cheakamus FSR’   
• Cheakamus River above Culliton Creek (pedestrian suspension bridge over
Cheakamus River above Culliton confluence), hereinafter referred to as ‘Cheakamus
Pedestrian’  
• Culliton Creek above Cheakamus River (Jack Webster bridge over Culliton Creek),
hereinafter referred to as ‘Culliton Creek’
Based on discussions with the working group for the Cheakamus Project Water Use Plan
Monitoring Program in January 2009 (Monitoring Advisory Committee Meeting), NHC
voluntarily undertook additional tributary flow gauging in Year 1 at four additional sites:
• Chance Creek above Cheakamus River
• Cheakamus River above Cheekye River
• Cheekye River above Cheakamus River
• Cheakamus River below Cheekye River
An additional hydrometric station was also installed in April 2009 on the Cheakamus River
below the Cheekye River confluence.  This work was carried out to supplement our
understanding of tributary flow contributions to the Cheakamus River and to develop rating
curves for these sites in anticipation of the need for a greater spatial extent of discharge
information on the system by the Monitoring Program working group.  Partial rating curves
were developed for each of these sites (3‐4 dissimilar discharge measurements at each site)
and have been presented in the Year 1 report (NHC, 2009).  Rating curve development for
the additional sites was discontinued as of June 2009 since there was no apparent interest
in expanding the existing Cheakamus River hydrometric network.  The Cheakamus River
hydrometric station situated below the Cheekye River confluence remains, but has been
inaccessible and possibly inoperable since the Cheekeye debris flood in 2009; the station is
likely recording data but has been covered by a substantial amount of sediment.
Hydrometric stations situated at the above sites continuously log water temperature and
water level (stage) data at 15‐minute increments, with barometric pressure and air temperature monitored at the Culliton Creek site. This project requires that flows be
estimated at the Cheakamus River sites for a specified range (minimum flow s up to 60
m3
/s), with a full range of flow estimation for the period of record at Culliton Creek, which is
the largest single source of inflow between the Daisy Lake Dam and the Cheekye River.
Discharge measurements have been used to further refine the rating curves submitted in
the Year 1 report (NHC, 2009). Changes in channel geometry can cause the relation
between stage and discharge to change over time. For example, channel erosion or
deposition during storms events, or the placement of bank protection works, can affect the
stage‐discharge relation. For this reason, water levels are physically measured during each
site visit and compared to transducer stage data to ensure the accuracy of the
instrumentation over time. Each new discharge measurement is also compared against the
existing rating curve and the yearly stage record to determine if a new rating curve must be
developed following a high flow event or a shift in the stage data.
Instantaneous measurements of flow for the development of site‐specific stage‐discharge
rating curves have been conducted using a variety of methods. When possible, we have
employed a velocity‐area approach to estimate instantaneous discharge on the Cheakamus
mainstem with an Acoustic Doppler Current Profiler (ADCP) 1
.  If stream flow conditions are
not suitable for this method, our second choice is to utilize either mechanical or acoustic
velocity meters to provide mean velocities at a minimum of 20 or more intervals across a
stream cross‐section (RISC, 2009).  A Price® velocity meter was utilized for this method on
only one instance at the Cheakamus Pedestrian site (Table 2).  Excessively turbulent stream
conditions, such as at Culliton Creek, preclude the use of acoustic or mechanical velocity
meters, but instantaneous flows have been successfully measured with salt dilution and
Rhodamine WT dilution gauging methods.  Details on flow gauging and monitoring
methodologies are briefly described in subsequent sections, and for more detail the reader
is referred to the following publications (attached): 1) Moore (2004a, 2004b, & 2005) and
Hudson and Fraser (2005) for salt dilution methods, and 2) Teledyne RD Instruments (2009a
& 2009b) for acoustic profiling methods.  Rhodamine WT dilution is analogous to the salt
dilution method.   
Rating curves are provided in Figure 1 ‐ Figure 3 along with extrapolation lines indicating the
limit above which flow hydrograph estimates for each site are beyond the range of
measured flows.  Instantaneous discharge measurement errors are provided in Table 2,
where error bounds are one standard deviation for ADCP measurements, and 10% for
dilution and velocity‐area methods.  Mean daily streamflow hydrographs are provided in
Figure 4 ‐ Figure 6 for each site, with water and air temperate from the Culliton Creek site.
Information Type report
Regional Watershed Howe Sound & Sunshine Coast
Sub-watershed if known Cheakamus River
Aquifer #
Comments
Project status complete
Contact Name
Contact Email