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