River Velocity Method, Justification & Formulae

Question 1

River Velocity Method, Justification & Formulae

Answer 1

River Velocity Method:

One method of primary data collection was measuring the velocity of the river (m/s) by the ‘Float and Time method.

1. We measured a 5 metre stretch of the river using a 30 metre tape measure.
2. Then, one person stood in the river at the start of the 5 metres with a ping pong ball (a universal indicator of velocity because of it’s spherical uniform shape and light weight) and released in onto the surface of the river channel.
3. Following this, we timed, using a stop watch, how long it took for the ping pong ball to travel 5 metres.
4. We repeated this method 5 times to get an average time, as using this mean time we would be able to calculate the river velocity using the equation -

(V) Velocity ((m/s)) = (D) Distance ((m)) x (T) Time ((s))

Justification:

This measurement of river velocity was vital as it was integral to our hypotheses, because in order to calculate discharge, river velocity is required:

(Q) Discharge ((m³/s)) = (V) Velocity ((m/s)) x (A) Cross-sectional Area ((m²))