Amendments to the hydrological sub-models of the Wallingford procedure (SR 166)

This report provides details of planned amendments to the hydrological models incorporated within the Wallingford Procedure for the Design and Analysis of Urban Drainage Systems. Part 1 provides a detailed design specification for a new sewered sub-area model to represent the hydrological behaviour of large urban subcatchments. This amendment is necessary for the practical implementation of the water quality model MOSQITO currently being developed at HRL under contract from the Department of the Environment. Part 2 summarises a new surface hydrology model incorporating improved calculation of rainfall losses and flow storage and diversion on urban catchment surfaces.