A model will be used to estimate rainfall$-$runoff relationship at a given watershed.

The $1-$hr storm for the $100-$Year recurrence rainfall intensity is used for design

purposes. The Intensity$-$Duration$-$Frequency curve for $100-yr$ recurrence is obtained

from the equation shown below in which, $L$ is rainfall intensity $(i\frac{n}{h}r)$ and tr is

rainfall duration $(min).$ This equation assumes constant rainfall intensity during the

storm duration event used by the proposed model.

$I=\frac{560}{20+tr}$

Assume initial abstractions and interceptions are $5\%$ of the total rainfall depth.

Use the Horton's equation to model the infiltration component of the hydrologic

model in a small watershed. The initial infiltration capacity is $4i\frac{n}{h}r,$ the equilibrium

infiltration capacity is $0\mathrm{.}3i\frac{n}{h}r$ and Horton's time constant is $1\mathrm{.}25h{r}^{-1}($using t in

hours$).$

Determine $($showing equations, all computations and their corresponding units$)$:

A$)$ The $1-$hr rainfall intensity for the $100-$Year recurrence period $($in$./$hr$).$

B$)$ Total rainfall depth after $1$ hour of constant rainfall $($in$.).$

C$)$ Water depth is associated only to the initial abstractions and interceptions for this

model $($in$.).$

D$)$ Infiltration rate value after $1-hr(i\frac{n}{\frac{?}{?}}hr).$

E$)$ Total volume of infiltration per watershed unit area $=$ total infiltration depth after

$1-hr($in$.).$

F$)$ Effective rainfall or net direct runoff depth due to this rainfall event $($in$.).$