Diversion Channel

Brief Introduction

Diversion channel is a way of construction diversion by building a channel to fall through the down stream. Diversion channel is usually used for the river diversion of outside the river bed, applicable to the river valley with gentle bank slope, wide beaches, or the landforms with streams or old river courses; besides, the amount of the diversion is large. Comparing with tunnel diversion, the diversion channel has a larger amount of diversion, more convenient in construction, lower in cost, when the orographic condition and the hinge arrangement are allowable, there are more diversion channels.

The Factors

There are several factors to be considered while arranging the diversion channel. First, axis position, as for the landform, it would be better to set on the beaches with convex bank and may make use of pass, stream and old river course. Second, the entrance of the diversion channel should be able to make the water flow smoothly, and keep distance with the cofferdam to avoid the sluicing of the toe. Third, the height of the entrance and exist should be set according to the specific flow rate, navigation and sluice. Fourth, the section of the channel may choose from the rectangle, trapezium and compound section.

The Diversion Channel of Three Gorges Project

Diversion Channel is 3410 meters long and 350 meters wide, and the width of it is one third that of the Yangtze River, being the main item of the first stage of Three Gorges project. The planned flow rate of navigation is 20,000 square meters per second. When the flow rate of the water is over 20,000 square meters per second, the ships will sail through the temporary ship lock. During the construction, the excavation of cubic meter of earth and stone is 28.2368 cubic meters, taking up one third of the whole excavation. The Diversion Channel began the trial trip on July 1, 1997, and started the formal trip on October 1, 1997. All the ships changed the way to Diversion channel, with a term of validity of 6 years. Then diversion channel took the responsibility of navigation of the Yangtze River and flood sluice. On November 6, 2002, the diversion channel is successfully closed, the power plant on the right bank stayed on it