Reducing uncertainty in the hydraulic analysis of canals

British Waterways is the largest navigation authority in the UK, managing a network of 3200 km of inland waterway. Central to this function is the management of a large and complex water supply system: water is transferred across the network for resource management, to maintain navigation, for sale to third parties and for flood relief. Understanding the movement of water is essential to the effective and efficient management of this system. One-dimensional hydraulic models are routinely employed by water engineers to investigate such regimes throughout the UK. This paper describes recent studies aimed at reducing the uncertainties associated with the application of such models. This was achieved with a programme of primary research that included extensive site surveys, hydraulic trials and modelling. The outputs of this work include: validation of Manning's roughness representation for canals; determination of roughness coefficients for a range of bed and bank protection types; development of a practical relationship for determining the effective roughness of vegetated canals; and the quantification of the impact of canal constrictions. This work is of interest to consultants, researchers and those who undertake hydraulic modelling studies of canal systems.