SRT Upstream & Downstream Hazard ID 2

Question 1

A rescuer standing on the bank sees a 'horizon line' across the river ahead. What does this indicate?

Accepted Answer

A drop or significant change in gradient that may conceal a hazard

Answer

A horizon line—where the river surface disappears from view—signals a drop, falls, or hydraulic feature that must be scouted before approach.

Question 2

Pillow water forming on the upstream face of a submerged rock is a useful indicator because it shows:

Accepted Answer

Water is deflecting off the obstacle, signaling a sub-surface hazard

Answer

Pillow water is created when current hits an obstacle and deflects upward, warning rescuers of a submerged or partially submerged object.

Question 3

Which visual characteristic most reliably identifies a low-head dam from an upstream river approach?

Accepted Answer

A uniform, horizon-wide line of white water with a glassy lip above it

Answer

Low-head dams present a uniform, wall-to-wall horizon line with a deceptively smooth glass lip above the recirculating trough.

Question 4

A rescuer observes boils and upwelling on the river surface in what appears to be flat water. This most likely indicates:

Accepted Answer

Sub-surface turbulence from submerged structures, rocks, or hydraulics

Answer

Boils and upwellings on the surface reflect sub-surface turbulence—often caused by submerged boulders, bridge footings, or hydraulic backwash.

Question 5

When assessing river gradient, a steeper gradient generally means:

Accepted Answer

Higher current velocity and increased potential for dangerous hydraulics

Answer

Steeper gradient increases current velocity, which amplifies the force and danger of hydraulics, strainers, and impact with obstacles.

(SRT) Swiftwater Rescue Technician Certification Practice Test