SPATIAL VARIABILITY IN FLOOD ESTIMATION FOR LARGE CATCHMENTS - THE EXPLOITATION OF CHANNEL NETWORK STRUCTURE

A methodology for incorporating spatial variability into a unit-hydrograph type flood estimation procedure is presented. The method centres on the use of a network width function, which describes the spatial disposition of channels within a catchment, a two-parameter routing function, and a hillslope response function. The spatial variability is expressed in terms of weights applied to the network width function. The method is illustrated with respect to both soil type, as described by the winter rain acceptance potential, and total event rainfall in seven events on the River Thames at Cookham, UK.