ACA Water Reading & River Hydrology Flashcards

What is a 'wave train' in river hydrology as described in ACA instruction?

Answer: A series of standing waves formed by fast water flowing over a rocky riverbed

A wave train is a series of standing waves created where fast-moving current flows over irregular bottom features, typically offering an exciting but manageable downstream path.

How does an undercut rock differ from a regular submerged rock in ACA hazard assessment?

Answer: Undercut rocks extend horizontally below the surface, trapping swimmers who are swept under them

An undercut rock has a horizontal shelf extending underwater that can trap a swimmer or boat beneath it with no route to escape, making it one of the most dangerous river features.

What does CFS stand for in river gauge measurement as used in ACA instruction?

Answer: Cubic Feet per Second

CFS stands for Cubic Feet per Second, the standard US measurement unit for river discharge volume used to assess runnable conditions.

What is the 'Venturi effect' as it applies to river channels in ACA water-reading instruction?

Answer: Current accelerating as a river channel narrows, compressing flow

The Venturi effect describes how water accelerates when forced through a constricted channel, creating faster and more powerful currents at narrows.

What is a 'horizon line' in river scouting terminology as taught by ACA?

Answer: The visual edge where a river drops out of sight, indicating a significant rapid or waterfall ahead

A horizon line is the visual cue where the river surface disappears into the distance, indicating a significant drop, waterfall, or major rapid that requires scouting.

In ACA instruction, what is 'laminar flow' and why is it important for paddlers?

Answer: Smooth, non-turbulent water moving in parallel layers that offers predictable paddling

Laminar flow is smooth, non-turbulent water moving in parallel layers, offering paddlers the most predictable and efficient paddling conditions.