In this model,the solving method of sediment transport equations under complex flow conditions has been presented,including sediment distribution method at junction nodes,and modification model at flood diversion gate.

n this paper,based on the,flood characteristics and the current status of tile flood control worksin the middle and lower reaches of the Hahjiang River,a bivariate probability model is developed for calculatingthe flood diversion operation frequency of the Dujiatai Project.

The former 2-D flow mathematic model for flood detention area constructed is improved and a new mathematic model is set up in the paper considering the difference between water flow movement peculiarities inside and outsider of river channel.

As the population grows and the economy develops in flood detention areas,the landform in flood detention areas becomes complicated,which brings difficulties in simulating the flood flow in flood detention areas.

The flood detention areas play an important role in flood-preventing project of river,because it can divert and store the excessive flood from the river.

Through the project example of Shaheyong flood-diversion channel structure design in Guangzhou City, the paper introduces large-span two-span channel box, tunnel by shallowly embedded and blindly dig, the use condition and advantage of mechanical jacking technology, respectively.