storm sewage system in city area and storm sewers required

Storm sewage runoff

We have already discussed that the amount of liquid waste that flows into the sewers during the rainy season is called storm sewage.

Why storm sewers are needed

Storm sewers required

Storm sewers are needed for the following reasons:

(a) To avoid the creation of unfavorable healthy conditions.
(b) To improve the general appearance of the city.
(c) To dispose of the wash as soon as possible before the early rain.
(d) For keeping the structures safe by not allowing to enter the water in their foundation.

In order to determine the storm sewage (i.e. the quantity of storm water), the following empirical relations may be used :

1. According to Fanning's formula, the quantity of storm water (Q) in litres per second is given by

where                                   C  =  A constant, and

                                             A  =  Area of catchment in sq. km.

2. According to Dicken's formula,

3. According to Ryve's formula,