River Kelvin Case Study
Steady Flow Analysis
Theory
1D Steady Flow Modelling
Geometrical data
River cross-sections + distance between them.
x
Q
h
Hydraulic structures
1D Steady Flow Modelling
Equation
v12
v22
z1  y1  1
 z 2  y2   2
 E
2g
2g
z1  y1  water level
v  mean velocity v  Q / A
Solution
  the energycoefficient
Standard step method.
E  energylossbetweensections1 and 2
Q
2
Z+y
1
x
1D Steady Flow Modelling
Boundary Conditions
Upstream – constant inflow.
Q
Downstream – known water level.
T
Q
h
h
T
Q
1D Steady Flow Modelling
Prediction
Water level at each cross-section.
x
Q
h
Advantages
Easy to predict maximum water level.
River Kelvin Case Study
Steady Flow Analysis
Case Study
River Kelvin Case Study
The December 1994 Flood
Rainfall event with a return period between 1 in 300 and 1 in 1000
years.
Flood return periods
• Lower River Kelvin 1
in 200 years.
•Main tributaries Luggie Water and
Glazert Water 1 in 50
years.
Flood outline 9 to 11th December 1994
River Kelvin Case Study
Consequences
Catastrophic flood which caused:
• Damage estimated at £10 million.
• Extensive damage to over 300 business and residential properties.
•The loss of two lives.
Inundation in Kirkintilloch
Flooding of McNair’s Factory
Overtopping of flood defences at Balmore
River Kelvin Case Study
Solution
Options considered:
• Flood storage – discounted due to timing of flood peaks.
• Channel dredging – discounted due to environmental damage and
increased flood peaks downstream in Glasgow.
Solution adopted was a
system of direct
defences using earth
embankments and
retaining walls, the
location of which was
chosen to preserve as
much of the existing
flood plain as practical.
River Kelvin Case Study
Solution
Examples of the direct defences
used of the River Kelvin flood
defence scheme.
River Kelvin Case Study
Steady Flow Analysis
The Task
River Kelvin Case Study
Model Calibration
The HEC-RAS model provided has been set up with:
• Gauged inflows for the River Kelvin and its tributaries
for the December 1994 flood, Table 1.
• A rating curve downstream boundary based on uniform
flow.
• Manning’s ‘n’ values of 0.02 and 0.01 on the flood plain
and main channel respectively.
Calibrate the model by altering the Manning’s ‘n’ values to
obtain a reasonable agreement ± between the observed
results provided in Table 2 and the computed values.
River Kelvin Case Study
Flood modelling
• Use the calibrated model to estimate flood levels for the
50, 100 and 200 year flood events, inflow data is
provided in Table 3.
• Determine the maximum defence levels for a flood
prevention scheme for Kirkintilloch.
River Kelvin Case Study
Reporting
The case study report should include:
• A map showing the location liable to flooding for a
return period of 1 in 200 years.
• Details of required flood defence levels in the location of
Kirkintilloch.