$(25$ points$)$ A $20-$acre vacant and undeveloped land will be developed into heavy industrial

facilities. Given the parameters below, estimate the peak$-$discharge rate from this land before

and after development, assume the design is targeting a $15-$year design event.

Before development: Time of concentration: $60$ minutes; Runoff coefficients: $0\mathrm{.}2$;

After development: Time of concentration: $20$ minutes; Runoff coefficients: $0\mathrm{.}8$ ;