and Answers 100% Pass
Total Percipitation equation - ✔✔Total percipitation=initial
abstraction+infiltration+surface runoff
Damage categorization of floods - ✔✔Nuisance, damaging, and
devastating
Parameter required to design culverts and storm drains - ✔✔Peak runoff
Rational Method equation - ✔✔Q=CIA
Q=Peak runoff (in-ac/hr or cu.ft/s)
C=runoff coefficient
I=rainfall intensity (in/hr)
A=area (acres)
Rational method assumptions - ✔✔Constant rainfall
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Katelyn Whitman, All Rights Reserved © 2025
, Recurrence interval for peak flow is same as for design storm
Runoff coeff is constant
Usage of method only valid for small areas
NRCS rainfall runoff method equation - ✔✔Q=(P-0.2S)^2/(P+0.8S)
Q=total runoff (in)
P=gross rain (in)
S=storage capacity (in)
NRCS rainfall runoff method assumptions - ✔✔Exponential decay of
infiltration
Losses from interception, storm period evap, depression storage,
infiltration assumed 20% of storage area
Conservation equation - ✔✔Q=Av
Q=flow
A=area
v=velocity
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Katelyn Whitman, All Rights Reserved © 2025