SRT Upstream & Downstream Hazard ID 3

Question 1

Which characteristic most distinguishes a 'keeper' hydraulic from a non-keeper hole?

Accepted Answer

A keeper recirculates objects back into the trough rather than flushing them downstream

Answer

A keeper hydraulic recirculates objects—including swimmers—back into the trough due to the geometry of the backwash, making escape extremely difficult.

Question 2

From upstream, what distinguishes a standing wave from a hydraulic (hole) in terms of visual appearance?

Accepted Answer

Standing waves show continuous downstream-moving crests; holes show a recirculating foam pile with a trough

Answer

Standing waves move water downstream continuously, while holes display a recirculating foam pile and visible trough where water cycles back upstream.

Question 3

A 'pourover' feature is hazardous primarily because:

Accepted Answer

Water pours over a ledge and creates a recirculating hydraulic trough below

Answer

Water pouring over a ledge accelerates and plunges into a pool, creating a recirculating trough that can trap and recirculate swimmers.

Question 4

Which river feature is described as a 'hydraulic' versus a 'stopper' in swiftwater rescue terminology?

Accepted Answer

The terms are often used interchangeably for a recirculating hole feature; 'stopper' emphasizes its ability to halt downstream progress

Answer

Both terms describe recirculating holes; 'stopper' is commonly used in British/European contexts and emphasizes the feature's ability to stop and retain swimmers or boats.

Question 5

An undercut rock is particularly dangerous because:

Accepted Answer

Current flows beneath the rock, creating a void that can trap and pin a swimmer with no escape

Answer

Undercut rocks have cavities beneath them where current flows—a trapped swimmer is pinned by hydraulic force with no upstream or downstream exit.

(SRT) Swiftwater Rescue Technician Certification Practice Test

(SRT) Swiftwater Rescue Technician Certification Practice Test

SRT Upstream & Downstream Hazard ID 3