Which of the following features is associated with the upper course of a river?

A waterfall is the feature associated with the upper course of a river. In the upper course (near the river's source, typically in highland or mountainous terrain), the river flows over steep gradients with high velocity. Where the river crosses bands of rock with different levels of resistance, the softer rock is eroded more quickly than the harder rock, creating a sudden vertical drop in the riverbed. This produces a waterfall.

The upper course is characterised by vertical erosion (downcutting), steep-sided V-shaped valleys, interlocking spurs, rapids, gorges, and waterfalls. The river here has a small volume but high energy due to the steep gradient.

The other features belong to the middle or lower course of a river:

• A meander is a winding bend in a river, typical of the middle and lower courses where lateral (sideways) erosion becomes more significant than vertical erosion.
• A levee is a raised bank along the sides of a river in its lower course, formed by the deposition of sediment during floods.
• A delta is a fan-shaped deposit of sediment formed at the mouth of a river where it enters a sea or lake, characteristic of the very end of the lower course.