Practice exam question

@coachbryanhoward Hi can you explain how lowering channels leads to erosion? I thought filling in a channel would allow an area for water. I’d like to understand how best ways to manage the site in a scenario for site questions. I put the question below.

The owner provides a topographic survey of the greenfield site of a new shopping mall. The architect noted the site has several steep vegetated hills.

What site strategies should be put in place to mitigate erosion? Check the three that apply.

Revegetate and mulch exposed areas

Correct. Added vegetation and mulch help to hold disturbed soil in place and limit erosion from runoff.

Design development to fit the site and the terrain

Correct. Situating the building on an area of the site with flat terrain will limit disturbance of existing soils, which leads to a greater chance of erosion.

Protect and retain existing vegetation

Correct. Existing vegetation is already established on the hillside and helps prevent erosion from rainwater.

Grade the site by filling in channels

Incorrect. Filling in channels will lower natural flow capacity, causing them to receive larger amounts of water in shorter periods of time, will lead to erosion.

Clear trees and shrubs from hilltops

Incorrect. A lack of windbreaks (trees, shrubs, etc.) allows the wind to put soil particles into motion for greater distances, thus increasing soil erosion.

Strip topsoil from steep hills

Incorrect. The loss of topsoil creates major site damage. The onsite loss of this upper layer of soil nearly eliminates the soil’s natural ability to provide nutrients, regulate water flow, and combat pests and disease.

Reference: Site Planning and Design Handbook

@sergioclaure93 :

This is an interesting problem. By grading the site and filling in the naturally existing channels you are changing the way that the water wants to run off of the site. This creates a risk of erosion in the areas that were filled as the site tries to return to its natural water shed state. The site does not exist in isolation, the water on the site wants to get to a natural shed point that is continued onto and from adjacent sites.

Try to keep sites as natural as possible.

Ok I see, good to know for the site analysis type questions.

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