LARE LARE Drainage System Design 4

Question 1

A stormwater system must pass a 100-year storm event. Which design element is specifically sized to convey this extreme flow?

Accepted Answer

The major conveyance system including overland flow paths and open channels

Answer

The major conveyance system — streets, channels, and overland flow paths — is designed to safely convey extreme storm events like the 100-year storm.

Question 2

Which soil characteristic is most important to measure before designing an infiltration-based BMP such as a permeable pavement system?

Accepted Answer

In-situ saturated hydraulic conductivity (Ksat)

Answer

In-situ saturated hydraulic conductivity (Ksat) determines how quickly water moves through the native soil, which directly controls infiltration BMP performance.

Question 3

What is the key hydrologic advantage of green infrastructure over conventional gray infrastructure in urban areas?

Accepted Answer

Green infrastructure restores predevelopment hydrology by promoting infiltration and evapotranspiration

Answer

Green infrastructure mimics natural hydrology by returning water to the ground and atmosphere, reducing runoff volume and restoring watershed water balance.

Question 4

A site's pre-development CN (curve number) is 65 and post-development CN is 85. What is the primary design implication?

Accepted Answer

Post-development runoff volume will be significantly higher, requiring stormwater management

Answer

A higher CN indicates more runoff generation, meaning development has increased impervious cover and requires stormwater management to reduce post-development runoff.

Question 5

In open channel hydraulics, critical flow occurs when:

Accepted Answer

The Froude number equals 1.0

Answer

Critical flow occurs when the Froude number (Fr) equals 1.0, representing the transition between subcritical and supercritical flow.

LARE Test Practice Test

LARE Test Practice Test

LARE LARE Drainage System Design 4