A study of the scour-fill threshold based on Lane's equilibrium relation: The lower Yellow River

The scour-fill threshold in river channels is an expression of scour-fill equilibrium, which may be understood as the balance between the river's sediment carrying capability and the sediment load imposed by the drainage basin. In the present study, the above capability-load relation is quantified using Lane's relation, gamma QJ-Q(s)D(50), wherein Q is water discharge, J is channel slope, Q(s) is sediment transport rate, D-50 is median size of bed material, and gamma is the specific weight of water. On this basis, we have established scour-fill thresholds for the lower Yellow River based on data from 141 flood events. The results show that the Q(s)D(50)-gamma QJ relation may well distinguish between the scour and fill flood events. The following equation has been established: SDRFE = 0.00099(gamma QJ)(0.90()Q(s)D(50))(-0.60), wherein SDRFE is channel sediment delivery ratio. From the equation, the scour-fill threshold is established as: Q(s)D(50) = 0.00001 (gamma QJ)(1.5). Starting from this formula, four possible options are proposed for sediment management of the lower Yellow River. (C) 2015 Elsevier B.V. All rights reserved.