Theme 1-10-Multilinear discrete cascade model for stage hydrograph routing

Abstract

A method for routing stage hydrographs in rigid bed channels using multilinear modelling approach is presented. A discrete cascade model, which uses stage as the operating variable has been proposed in this study and it is used as the sub-model for this multilinear stage hydrograph routing method. The parameters of the sub-model are related to channel and flow characteristics by adopting the same relationships established for the corresponding parameters of the discrete cascade model operating on discharge variable. The suitability of this flood routing method is studied by routing a number of hypothetical stage hydrographs for a reach length of 40 km in uniform rectangular channels of different configurations. The solutions obtained using this method are compared with the corresponding solutions of the St.Venant equations. The study reveals that the proposed multilinear stage hydrograph routing model reproduces the St.Venant solutions closely when the rating curve corresponding to the input stage hydrograph is characterised by a narrow loop.