Part III: Cumulative $(41$ pts$)$

Fill$-$in the blanks $(14$pts$)$

$.(1$pts$)$ In a typical IDF plot, for the same rainfall intensity, will the $20-yr$ frequency have a

shorter rainfall duration than the $50-yr$ frequency $($yes$/$no$,$ please circle$)?$

$.(2$ pts$)$ Four rain gauge readings were obtained for a watershed: $0\mathrm{.}5in,5in,4in,$ and $3in.$

Compute the mean precipitation for this watershed using the arithmetic mean method.

$.(4$ pts$)$ When the rainfall rate is greater than the infiltration capacity, will there be any

runoff $($assume other rainfall abstractions are negligible$)?($yes$/$no$).$ In this case, what

is the infiltration rate?

$4.).(1$pt$)$ A hydrograph is used to represent

$.(2$pts$)$ The duration of a hydrograph is usually much longer than the rainfall event. List the

two components that make up the duration of a

hydrograph.

$.(4$pts$)$ List the final components of a hydrograph when the soil field capacity is exceeded

and when the rainfall rate is greater than the infiltration capacity.

$(10$ pts$)$ For a rectangular open channel with a cross$-$sectional area of $40m^2.$ Find out the

dimensions of the optimum hydraulic design.