Question

Why is the average velocity of a stream difficult to determine?

a) Streams always flow at a constant speed
b) The velocity is affected by factors such as depth and irregularities in the streambed
c) Average velocity is a concept that does not apply to streams
d) Measuring stream velocity is an easy and straightforward process

Answer 1

The average velocity of a stream is difficult to determine due to the impact of depth and irregularities in the streambed affecting the velocity. The formula Q = Av is used for calculation, but in some scenarios, the resultant velocity can be unrealistically high, indicating possible errors in given data.

Step-by-step explanation:

The question addresses the difficulty in determining the average velocity of a stream. The correct answer to why this is challenging is that the velocity of a stream is affected by a variety of factors, such as its depth and the irregularities found within the streambed.

These factors can cause the velocity to vary significantly from one point to another within the stream. To calculate the average velocity, one would typically use the formula Q = Av, where Q is the flow rate, A is the cross-sectional area, and v is the average velocity.

If we apply this to a mountain stream that is 10.0 m wide and on average 2.00 m in depth with a spring runoff flow of 100,000 m³/s, we find an average velocity that is unreasonably high, suggesting either an error in the flow rate given or the measurements of the stream's dimensions.