is economical than circular section
provides self cleansing velocity at low discharges
is more stable than circular section
is easy to construct
grade of sewer
length of sewer
hydraulic mean depth of sewer
roughness of sewer
none of the below
equal to HMD when flowing full
less than HMD when flowing full
greater than HMD when flowing full
to decrease it
to increase it
fluctuating
nil
circular brick sewer
circular cast iron sewer
semi-elliptical sewer
horse-shoe type sewer