Fluvial morphology analysis of the Yichang navigation channel after the TGP operation

Since 2003, the operation of the Three Gorges project (TGP) has obviously decreased sediment transportation into the downstream Yichang navigation channel. Therefore the erosion & incision of this channel and the deterioration of navigation condition can be expected. A fluvial morphology analysis of Yichang channel was given in this study and the results showed that: the main erosion zone has moved downwards during 2003~2006 so that the roughness coefficient in the near-dam section has increased more than 30%. The riverbed armoring calculation methods based on incipient possibility rather than those based on incipient velocity/grain size were also suggested in this channel for prediction of size distribution.