ABSTRACT
Faced with frequent and serious flood threat every year, the flood protection region of the middle and lowerYangtze River is one of the most vulnerable areas in center China. Particularly from Jingjiang River to Dongting Lake, once dike-break event occurs, it will cause a devastating disaster characterized with long inundated duration, heavy economic loss and a large number of deaths (Zong & Chen 2000). During the past decades, many flood-control reservoirs have been built on the upstream of theYangtze River and its tributaries and a large-scale leading reservoir group has taken initial shape (Li et al. 2013). But conflicts between safety discharge capacities of downstream river channels and the upstream inflow floods with high peaks and large volumes are still prominent. Encountering another 1954 type flood, there still exist about 40 billion m3 excess flood volume to be dealt with by flood detention areas. In addition, the single use of Three Gorges Reservoir (TGR) would not work efficiently for decreasing damage in another 1998 type flood (Hayashi et al. 2008).
