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a$.$ Water flows in a rectangular, concrete, open channel that is $12$ m wide. The channei slope is $0\mathrm{.}0028.$ If the velocity of the flow is $6\frac{m}{s},$ find the depth of the flow. $)=(0\mathrm{.}013$

b$.$ State two $(2)$ advantages of each of the following materials for constructing a culvert.

i$.$ Concrete

ii$.$ Aluminum pipes

iii. High$-$Density Polyethylene $($HDPE$)$

c$.$ Explain four $(4)$ factors that affect the quantity of stormwater runoff.

d$.$ The catchment area is $300$ hectares. The surface cover in the catchment can be classified as gi ven below:

$\backslash$table$[[$Type of cover,Coefficient of runoff,Percentage$],[$Single family dwelling,$0\mathrm{.}50,15],[$Roads$,0\mathrm{.}40,15],[$Rcofs$,0\mathrm{.}20,,10],[$Lawns and gardens,$0\mathrm{.}15,20],[$Open ground,$0\mathrm{.}10,15],[$Pavements and yards,$0\mathrm{.}80,,25]]$

i$.$ Calculate the runoff coefficient and quantity of stormwater runoff, if the intensity of rainfall is $40m\frac{m}{h}$ for rain with a duration equal to the time of concentration.

ii$.$ If the population density in the area is $250$ persons per hectare and the rate of water su pply is $120$ LPCD$,$ calculate the design discharge for a separate system and combined system. $($Use a peak factor of $2)$

State the two types of drainage systems and state any two basic functions of each.