What result occurs as a stream approaches a graded condition?

As a stream approaches a graded condition, the context of river dynamics and sediment transport becomes crucial. A graded condition refers to a state where a stream’s profile has reached a balance between sediment erosion and deposition. In this scenario, the energy of the stream is in equilibrium, allowing it to maintain a steady gradient and flow velocity.

In this balanced state, the stream tends to exhibit a natural tendency to erode laterally, which leads to the widening of the valley. This lateral erosion is a result of the established equilibrium between the sediment load and the stream’s capacity, allowing for greater accommodation of the sediment within the channel. Consequently, rather than deepening or downcutting, the stream will adjust by widening, which fosters a more stable, predictable channel shape over time.

The other options suggest different dynamics that wouldn't contribute to an approaching graded condition. For example, downcutting implies a continued incision of the streambed, which contradicts the balanced state of a graded stream. A channel that becomes completely straight would not typically represent a naturally occurring graded condition, where sinuosity is often retained or enhanced due to sediment dynamics. Lastly, a significant drop in stream level does not reflect the balanced state but rather hints at an unbalanced condition, typically driven by