Research On The Parameters Of Channel Regulation In The Yangtze Estuary

As one of the world’s largest and busiest navigable estuary, Yangtze estuary delta is the most active region of economic in China. With the rapid development of international shipping and the upsizing of cargo ship, the study of channel regulation parameters in Yangtze estuary becomes more and more necessary.After analyzing the characteristics of hydrologic and sediment in the Yangtze estuary, hydrodynamic mathematical model was built by the software of Deflt3d, which covered the area from Xuliujing to open seas in the year of 2011. From the numerical simulation, the annual tide process data of Baimao section can be extracted, combining it with the measured tide level materials from Xuliujing tide station for the whole year, we proposed a new calculation method for gradient of tidal river in this paper.By the new method, gradient of the Xuliujing to Baimaosha reaches can be gained, which is about 0.01216 (per thousand).Meanwhile, the average water level slope of flood season is higher than the dry season, and the bigger range of tide ebb,the greater of water surface slope will be.Based on the analysis of actual vertical velocity and the unit-width sediment discharge of 5 stations on the reache from Xuliujing to Baimaosha of Yangtze Estuary during 2011, it is found that the cross-section sediment discharge is proportional to the 2.9th power of the ebb tide cross-section velocity. Thanks to this discovery, the coefficient m of the Makavejev’s channel forming discharge formula is improved, and then the dominant discharge of Xuliujing and baimaosha reaches are respectively calculated to 60400 m3/s and 70400 m3/s, which are greater than the average annual discharge of ebb tide in a small degree. Furthermore, the effect of tide is much more than runoff to the tide reach of Yangtze Estuary downward Xuliujing. At the meantime, the channel-forming discharge of Xuliujing is 2.1 times of the average annual discharge of Datong (28400m3/s) and will increase downstream the reach.Figure out the regulation water level and regulation width of channel respectively according to the relationship of channel-forming discharge and transport rate-flow velocity. We put forward a new method to calculate the regulation water level, which is based on the interval frequency of the ebb level under channel-forming discharge. Take advantage of the result of numerical modeling, data of dischardge and water level were extracted every 30 minutes, and the classification of water level when channel-forming discharge appears with the space of 10cm is carried out, at the same time, count the frequency of level in every interval, and at last, we get the mean water level in intervals to the greatest frequency, which is used as the regulation water level. Based on sediment transport equilibrium and the relationship between transport rate and velocity, we got a new regulation width formula which is suitable for the Yangtze estuary, with the new method, regulation width of Baimaosha import section is calculated to be 2172m.