| The reach of the Yangtze River between the Three Gorges Dam and the Gezhouba Dam will become a navigational bottleneck after the Three Gorges Project (TGP) is put into operation. Based on numerical model, Global Positioning System (GPS), and three-dimensional virtual simulation technique, a shipping monitoring & dispatching system that oversees the Miaohe-Huyatan reach of the Yangtze has been established in the dissertation. Navigable flow conditions in that reach and various functions of the developed system have also been studied. The results obtained are of great significance in fostering the development of water conservancy research both in theory and in practice.Two innovative results have been achieved (1-2) together with other supporting research findings (3-6). These are detailed as follows:1 A unified model for optimizing sailing courses has been established. The relationship among the speed of the ship, the angle of the hull to the flow, and the time required to traverse the river has been investigated. The results show that after optimization, the navigable time can be increased by 10.7 days, equivalent to an increase of 1.55 million tons in navigation capacity.2 An integrated shipping monitoring & dispatching system has been developed which unifies database, numerical model, GPS, and three-dimensional virtual simulation technique. The system permits flexible interactions among each module, and it possess all the functions such as three-dimensional scene browsing, information querying, object positioning, data listing & displaying, monitoring & pre-warning, emergency managing, navigation dispatching, and so on. It serves as an integral, intuitive, and straightforward supporting platform for optimizing navigation dispatching schemes.3 Two- and three-dimensional numerical flow models have been developed and verified with a combination of laboratory data and field data from the Miaohe-Hyuatan reach. Good agreement between model prediction and the measured data has been reported which ensures the reliable application of the developed model to the study of navigable flow conditions in the concerned river reach. 4 Analysis shows that the shipping industry will gain significant benefits thanks to the remarkable drop in flow velocity in the dam area during the early operation stage of TGP. The navigation requirements in flow condition can be satisfied for the 10000-ton towboats within the range of 4000～40000 m3/s in the Yichang reach. When the discharge increases to 45000m3/s, however, the flow conditions render it difficult for the 10000-ton towboats to navigate safely.5 It's shown that the flow conditions in dry seasons in the reach between the dams meet the requirements of large tonnage ships during the daily regulation period of the TGP power station without considering the riverbed fluvial process. The limiting discharge for the 10000-ton towboats is about 30000 m3/s when the Gezhouba water stage is kept at 66.0m. If the water stage falls to 63.0m, the corresponding limiting discharge reduces to 25000 m3/s. The limiting discharge can be lifted to 40000 m3/s if the maximum flow velocity is allowed to rise to 3.5 m/s.6 A ship monitoring system has been designed by employing differential positioning technique of GPS. Through positioning and tracing ships that navigate the Miaohe-huyatan reach, the dispatch of ships in this river reach and the management of ships passing the TGP lock can be realized in an effective and efficient way.
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