ENRP20001: 3-D Floodway Design Methodology Presentation T1 2018

This presentation details a 3-D floodway design methodology, addressing the challenges of extreme weather and public safety. It covers the problem statement, objectives, literature review, and design methodology, incorporating dimensional analysis and 3-D design modeling. The presentation delves into open channel flow characteristics, hydraulic shocks, frictional factors, and the Froude number. It includes a theory model, algorithm procedure, and design of experiment using a Gantt chart. The model features a trapezoidal channel cross-section for efficient flow, with calculations for dimensions, wetted perimeter, hydraulic radius, and average velocity using Manning's equation. The presentation concludes by comparing sluice gate and free fall over-fall cases, highlighting the impact on velocity and referencing relevant studies.

3-D FLOODWAY DESIGN
METHODOLOGY PRESENTATION
Flow Channel Development

INTRODUCTION
Problem Statement and Objectives
Major challenge with floodways is that they are often affected by
extreme weather change such as heavy downpour.
 Public safety is therefore at risk
Economic significance of such structures also diminishes
Hence aim is to develop a more structurally resilient
infrastructure that would serve the public in a safe fashion

Background
Structural resilience in critical infrastructure such as
floodways is essential as it greatly contributes to public safety
and institutional confidence (Javernick, Redolfi, and Bertoldi,
2018)
Extreme climatic change may alter the normal functioning of
these structures
Design engineers must look at the entire design architecture to
ensure resilience is restored especially in extreme weather
conditions
The biggest concern in major cities is the rapid urbanization

AIM
The project aims at establishing more
efficient and effective flood control structure
to improve public safety
It is assumed that the flow is open channel
hence various factors at play
Dimensional analysis and 3-D design
modeling
is utilized

LITERATURE REVIEW
According to Lokuge et al (2014), floodway
damage is mainly due to large boulders on
the channel bed.
Categorization of the damage include:
-Washout
-high water damage
-Rock structure damage (the latter is more
pronounced in most floodway channels

METHODOLOGY OF DESIGN
Problem Solving
Dimensional analysis would involve deriving
mathematical formulation using the
expression provided:

In Designing the channel
Parameters involved include: coefficient of
friction, density of flowing water, size of
channel and velocity of flowing water

Design Considerations
Open channel flow characteristics in
floodway design involves:
Considering hydraulic shocks for impact
loading and scouring
The frictional factor along the channel
The flow is also described using Froude
Number such that turbulent regimes are
distinct from streamline flow

Theory Model
To consider the components of Dimensional
Analysis : Viscosity, frequency, velocity
Sluice gate verses sharp crested weir
comparison
Flow characteristics
The developed floodway is trapezoidal in cross
section

Algorithm
Procedure Description
Firstly, I assume the flow s constant along the channel hence the following governing equation (based on energy and
mass conservation) to describe the various profiles given the conditions (Defna, and Bxo No “page”):
Dy/dx= 1/cos ϕ {(So-Sf)+ αV2/gAxdA/dx}/1-F2…(1)
Where F s Froude number given by F= {αV2/gD cos ϕ}1/2
To find the water profile y, can integrate equations 1 wth respect to x (n other words depth to vary with the
horizontal distance)
y= ∫ 1/cos ϕ {(So-Sf)+ αV2/gAxdA/dx}/1-F2dx…(2)
But since consider a prismatic channel, equation (2) bolts down to:
y= ∫ 1/cos ϕ {(So-Sf)/1-F2dx…(3)
Equation (3) which is further written as:
Dy/dx= (So-n2Q2/A2R4/3)/ 1-F2 … (4)
Now, using equation (4) above and the fact that the channel is trapezoidal, can undertake various calculations to
arrive at the profile:
The trapezoidal section:

Design of Experiment
Use of Gantt Chart for planning purpose
The experiment to be performed would be
time-based such that the extremity of the
condition is varied in steps until the
demolition state is attained
This would be repeated for three differently
designed floodways to check on structural
resiliency

THE MODEL
The channel cross section is
trapezoidal. The selected cross
section provides the most efficient
flow rate regime.