UNIVERSITY OF GUYANA
DEPT. OF CIVL ENGINEERING
HYDRAULIC ENGINEERING
(CIV 3201)
DESIGN PROJECT – CHANNEL DESIGN
You are to prepare a design report for a trapezoidal channel design. This report should follow a
design report standard. You can either research the format from an online source or a source that
consultancies within Guyana uses.
The details are as follows:
A section of a rural area for drainage comprises the following information:
LAND TYPE
AREA FRACTION
Gravel roadways
0.40
Rice fields
0.30
Vegetated area
0.25
Turf
0.05
The area is 1,000 acres in size. The length of the channel required is 12,000 feet. The overall area
has different velocities of overland flow in the different components. The lengths of each area that
require drainage are proportional to the area fractions. The velocities of the different areas are
shown in the table below:
LAND TYPE
AVERAGE VELOCITY OF WATER
RUNOFF
(feet/second)
Gravel roadways
2.0
Rice fields
1.5
Vegetated area
1.5
Turf
1.5
The channel that will be designed needs to cater for the discharge generated from a 50-year
frequency storm. The channel is trapezoidal and should be an excavated, open channel with natural
earthen lining. The resulting channel may have some weeds present. A longitudinal slope of 1 inch
over 3000 feet. Due to the type of soil, the side slope of the trapezoidal channel should be designed
for 1.5H:1V (horizontal distance: vertical distance).
The design is to be done using the rational method. It should be noted that the breadth/width (w)
to depth (d) ratio of the channel should lie between 2 and 3.
Resources:
•
Use all table and charts provided in the in-class lectures where necessary.
•
Manning’s formula is provided in the in-class lecture.
What a trapezoidal channel looks like:
Depth, d
Wetted
perimeter,
p
Width, w