 This curve dates back to early 20th century research on river geomorphology and has no more than a historical value nowadays, although its simplicity is still attractive.Among the drawbacks of this curve are that it does not take the water depth into account and more importantly, that it does not show that sedimentation is caused by flow velocity "deceleration" and erosion is caused by flow "acceleration".The dimensionless Shields Diagram is now unanimously accepted for initiation of sediment motion in rivers.