Revisiting the Harrison River stage-fall relation Dave
Hutchinson National Hydrologic Service Environment Canada
Vancouver, BC Page 2 Harrison River Last major tributary of Fraser
River Represents 3.5% of Fraser watershed but 16% of mean annual
discharge Fraser River lowlands population to more than 2.5 million
people Page 3 Harrison Fraser Confluence Page 4 History and
Motivation A.G. Smith (IWD) developed a stage-fall model (J- Curve)
for predicting mean daily discharge at the outlet of Harrison Lake
(WSC id: 08MG013) Mike 11 modelling of lower Fraser River has
questioned published mean daily values at the gauge Migration of
hydrometric computations to Aquarius Hydrometric Workstation Page 5
Excel J-Curve Model Page 6 Questions Can a new stage-fall relation
be developed for Harrison River? How do the results compare to the
J-Curve model? Page 7 Stage-Fall Models Applicable for steady flow
conditions where backwater is due to changes in energy slope over
the control reach Mannings Equation: Page 8 Constant-Fall Models If
the fall (F r ) can be assumed constant (i.e, channel control): Use
non-linear regression to fit the following equation (4 unknowns):
Page 9 Hydrometric Network (Fall relation) Harrison R below Morris
Creek [08MG022] Harrison Lk at Harrison Hotsprings [08MG012] Q mmnt
locn Page 10 Data and Methods 15 min water level at Harrison Lk
(08MG012) and Harrison River (08MG022) for Discharge observations
at 08MG013 (Harrison R) (n=50) All analyses and graphics conducted
using R (www.r- project.org) and associated packages (XLConnect,
ggplot2, zoo)www.r- project.org Page 11 Stage-Discharge Relation
Page 12 Fall-Adjusted Relation Page 13 Fall-Adjusted Relation Page
14 Results Page 15 Residuals Plots Page 16 Residuals Plots Page 17
Model Comparison Page 18 Model Comparison Page 19 Next Steps
Evaluate stability of new model (moving avg fall?) Determine if
bias in old model is due to technician error Conduct analysis of
mean daily flows against WSC revision criteria Integrate model
within WSC data production system (Aquarius) Page 20 Thank-you!
Page 21 Next Steps - Index Velocity?
