$2.(12$ pts$)$ The following hydrograph was produced by a rainstorm having a uniform intensity of

$3\mathrm{.}0i\frac{n}{h}r$ starting at $9AM$ and ending at $10AM.$ Measured hourly discharge rates $($cfs$)$ from a

$300-$acre drainage basin are listed below. The baseflow from $9AM$ to $2PM$ is a constant $100$

cfs$.$

a$)$ At what time did the direct surface runoff begin? $(1$pts$)$

b$)$ Determine the gross and net rain depths $($in inches$)(2$ pts$)$

c$)$ Based on the information given, derive an $1-$hr unit hydrograph $(3$ pts$)$

Feel free to expand the table.

d$)$ From the results in part c$,$ derive a $3-$hr unit hydrograph for the basin $(6$ pts$)$

Feel free to expand the table.