PREDICTING STAGE-DISCHARGE CURVES IN CHANNELS WITH BANK VEGETATION

Many flood-control channels are subjected to expensive and environment ally damaging maintenance practices to control vegetation growth in at tempts to preserve flood capacity. However, such maintenance regimes a re often based on vague and qualitative guidelines. There is a clear n eed for physically based methods of predicting the impacts of vegetati on growth on flow resistance and flood capacity. In the present note, a numerical hydraulic model is coupled with physically based flow-resi stance equations for gravel-bed materials and vegetation roughness ele ments. The resulting model is capable of simulating stage-discharge cu rves in channels with arbitrary cross-sectional geometry, gravel-bed m aterials and bank, and/or floodplain vegetation, including overbank fl ows. The new model is demonstrated to be capable of closely replicatin g the stage-discharge curve at a study site on a natural river channel . Finally, the model is demonstrated using examples in which the effec ts on flood capacity of seasonal vegetation growth are simulated at th e study site.