CPESC Hydrology & Hydraulics

Question 1

Which hydrologic method is most commonly used to estimate peak runoff rates from small urban and agricultural watersheds for erosion and sediment control design?

Accepted Answer

Rational Method (Q = CiA)

Answer

The Rational Method (Q = CiA) is the most widely used approach for estimating peak runoff from small watersheds, making it standard for erosion and sediment control sizing.

Question 2

In the Rational Method formula Q = CiA, what does the variable 'C' represent?

Accepted Answer

Runoff coefficient reflecting land cover and soil type

Answer

The runoff coefficient 'C' represents the fraction of rainfall that becomes surface runoff, varying by land use, soil type, and slope.

Question 3

Time of concentration (Tc) in hydrology is defined as:

Accepted Answer

The time for runoff to travel from the hydraulically most remote point to the outlet

Answer

Time of concentration is the time it takes for water to travel from the farthest point of the watershed to the design point, which determines the peak runoff rate.

Question 4

Which NRCS (SCS) Hydrologic Soil Group has the highest runoff potential and lowest infiltration rate?

Accepted Answer

Group D

Answer

Hydrologic Soil Group D soils (clays, shallow soils) have very low infiltration rates and produce the highest runoff, making them critical to identify for erosion risk.

Question 5

Manning's equation is primarily used in erosion and sediment control to:

Accepted Answer

Estimate flow velocity and discharge in open channels and swales

Answer

Manning's equation (Q = (1/n)AR^(2/3)S^(1/2)) is the standard formula for computing flow velocity and discharge in open channels, ditches, and vegetated swales.

(CPESC) Certified Professional in Erosion and Sediment Control Practice Test

(CPESC) Certified Professional in Erosion and Sediment Control Practice Test

CPESC Hydrology & Hydraulics