A student is conducting a fieldwork investigation into downstream changes in bedload characteristics along a river channel. They use a ruler to measure the longest axis of 10 pebbles selected at a single point at each of their five sampling sites, and use a Powers' scale of roundness to grade them.
Suggest two ways that this bedload sampling methodology could be adapted to make the collected data more reliable.
102 exam-style questions on AQA GCSE Geography Fieldwork. Each one has a worked solution and a mark scheme showing where the marks go.