Problem# $1$

A storm sewer system for a watershed consists

of four areas A$,$ B$,$ C and D as given in Figure

The direction of flow from each area and

between the manholes is given by an arrow.

Using rational method, determine the $25-$year

peak flow for each sewer section. The IDF given

in Figure $2($Page $2)$ reflects the intensity$-$

duration$-$frequency relationships for the

watershed. Assume the time travel between each

manhole is $5$ minutes.

Figure $1$

Table $1$

Problem # $2$

For the same layout shown in Problem #$1$ above,

recalculate the design flow for each sewer section

by determining the overland flow using any

suitable method if the information provided Table

$2$ are applicable. The average velocity through

each sewer pipe $=4f\frac{t}{sec}$ and the rainfall

intensity $($in$/$hr$)$ is represented by an IDF

relationship $i=\frac{100}{t_c+15}$;$t_c$ in minutes.

Table $2$