Module 4

Question 1

What is a watershed?

Answer 1

A geographical region where hydrologic
inputs and outputs can be quantified

Question 2

What is discharge/streamflow?

Answer 2

Streamflow, or discharge, is defined as the volumetric rate of flow of water (volume per unit time) in an open channel

Question 3

What conditions must be met for streamflow measurements?

Answer 3

• straight channel, parallel streamlines
• stable (not loose/mobile streambeds)
• free of obstructions (large rocks, weeds)
• No back eddies, slack water and turbulent water
• An ideal cross‐section that is roughly parabolic, trapezoidal, or rectangular
• smooth, mirror‐like water surface (i.e., laminar flow)
• Steady, uniform, non‐varying flow conditions in the stream reach
• Flow velocities greater than 0.5 ft/s (0.15 m/s)
• Depths greater than about 0.5 ft (0.15m)

Question 4

What factors can affect streamflow measurements?

Answer 4

Measuring section suitability
Variable velocity
Equipment ‐ type and condition
Spacing of observation verticals
Rapidly changing stream stage
Ice impacts
Wind effects

Question 5

Is average or maximum velocity recorded at 6/10s depth

Answer 5

average

Question 6

Do you reset the flow meter in the air or in the water?

Answer 6

Water

Question 7

How many sections should the stream width be divided into

Answer 7

minimum 20

Question 8

Should the measuring tape be perpendicular or parallel to stream flow?

Answer 8

Perpendicular

Question 9

How long should a velocity reading be taken for?

Answer 9

30 seconds