Reducing uncertainty in conveyance estimation

Estimation of conveyance is a core component of flood management, water level prediction and flood defence design. All river modelling software includes one or more methods for conveyance estimation, usually based upon methods dating from research completed more than 50 years ago with little or no account taken of recent advances in knowledge and understanding. In 2001 the British Environment Agency commissioned, as a research project, a scoping study to define actions for reducing uncertainty in conveyance estimation. The paper describes some of the conclusions of that scoping study including the needs of different users, the diversity of current knowledge and the outline of the targeted programme of research that is now underway to produce an improved conveyance estimation system. Particular issues of concern are the effects of riverine vegetation, the influence of natural shaped (and re-naturalised) channels and the interaction between river channels and flood plain flows.