The value of integrating mathematical modelling with experimental work in both the laboratory and field is illustrated through the development of a software tool that deals with key practical issues related to rivers in flood. The Conveyance Estimation System software (www.river-conveyance. net) is aimed primarily at estimating the stage-discharge relationship, the distribution of depth-averaged velocity and boundary shear stress across channels of any prismatic shape for both inbank and overbank flows. The practical problems in obtaining data and the theoretical issues in identifying relevant flow parameters for stream wise and planform vorticity, turbulence shear stresses and frictional resistance are highlighted. The significance of these and their relevance to other hydraulics problems are noted. The issues involved in moving from data to theory (or vice-versa), then to practical application, are described in general terms, beginning with how to develop a model as a research tool, testing it against different data sets, through to using the model in practice with embedded tools. The tools deal with uncertainties in estimates and give guidance on roughness coefficients in natural channels.
