What does stream transport competence refer to?

Stream transport competence specifically refers to the largest size of material that a stream can transport for a given discharge, which is the volume of water flowing in the stream per second. This concept is crucial in understanding sediment transport dynamics within aquatic systems.

As the flow rate increases, the stream can carry larger particles, such as gravel and boulders. Conversely, at lower discharges, only smaller particles, like sand and silt, can be moved. Therefore, stream competence is primarily influenced by water velocity and flow conditions, which determine the capacity of the stream to lift and carry sediment.

In the context of the other options, while the speed of water flow and the volume of water are relevant factors in overall stream dynamics, they do not directly define what stream competence entails. The type of sediment present, although important in sedimentology, is not the definition of competence but rather one aspect of the sediment transport process. Therefore, the correct answer focuses specifically on the largest-sized material transportable by the stream given its discharge conditions.