53:078 Principles of Hydrology (Spring 2004)
Problem #29
Rational Method for Storm Sewer Design
The two sections of a storm sewer system (see sketch) must be designed to convey
the 10-year return period discharge. Estimate the design
discharges (i.e., the pipe capacities required just downstream of inlets) using the Rational Method. The
drainage areas, and runoff coefficients, and inlet times for each drainage are
shown on the sketch. Use the rainfall intensity-duration-frequency
relation (equation 6.2 in the text) for the Chicago area (see Table 6.2 in
text).
- Compute the 10-year peak discharge (in cfs) for the first (upstream) pipe section.
- Compute the 10-year peak discharge (in cfs) for the second (downstream) pipe
section.
Hint: Each storm sewer section must be designed to
convey the discharge from the entire area that drains through that
section. In some cases, the entire area draining through a section includes
runoff from areas that enter the storm sewer system at an inlet upstream from
the section.
Last changed on
04/22/04
by aab.