What is a Graded Stream?

A graded stream refers to a stream that has achieved an equilibrium between the processes of erosion and sediment deposition, allowing it to maintain a consistent slope. This particular slope is critical because it ensures that the stream has the necessary transport velocity to carry sediment away without being overloaded.

In a graded stream, there exists a dynamic balance where the amount of sediment being delivered to the stream is equal to the amount of sediment being eroded or transported downstream. When the slope is appropriate, the stream can efficiently manage the sediment load, preventing excessive accumulation that would alter its course or lead to a buildup of sedimentation.

Understanding this concept is essential in hydrogeomorphology, as graded streams play a vital role in shaping the landscape and maintaining ecological balances. A stream that is fully filled with sediment lacks the necessary slope for efficient sediment transport. Likewise, a stream that periodically goes dry or flows backward does not reflect the defining characteristics of a graded stream, which is primarily about the balance and slope necessary for sustained transport and flow.