Measuring Average Bedload Size

Equipment needed

(Caliper)

Quadrat

Caliper

Record sheet

Pencil

Procedure

Standing in the river, drop a quadrat onto the ground or into the water and allow it to settle. Select any pebble within the range of the quadrate. Fit the pebble horizontally (i.e. on its longest axis) in the gap of the caliper and take a reading of the length. Record the value. Rotate the pebble until it is vertical (i.e. on its middle axis) and take a reading of the length. Record the value. Repeat steps 2 to 5 until you have found the average bed load size of as many pebbles as you need to obtain your desired degree of reliability.