Study On Numerical Simulation Of Scour And Silting Evolution In The Lower Reaches Of Weihe River

After the implementation of the comprehensive control project of Weihe river basin, it is bound to affect the runoff and sediment of Wcihe. In this paper,the numerical simulation method is used to study the trend of scour and silting in the lower reaches of Weihe river, which provides the technical support for the follow-up treatment and management of the Weihe river basin, which has important practical significance.Firstly, several problems are discussed,such as the roughness of movable-bed and the silting velocity of non-uniform sediment in this paper. On the basis of these discussions, the mathematical model is improved. Based on the practical field data, the characteristics of water and sediment, scour and silting are analyzed briefly in the lower reaches of Weihe river and the Longmen?Tongguan river reach.The adaptability and the parameters of the improved model is calibrated by the practical field data of 1969?1995 and the model is validated by the practical field data of 2008?2012, The results showed that the mathematical model calculated volume of scour and silting is well in accordance with the practical measured volume. Finally, by using of the mathematical model, it is predicted the erosion and deposition prcess and the flood elevation of different flow rate in the lower reaches of Weihe river with 3 different water and sediment series.The main conclusions are as follows: (1) In terns of the cumulative scour and silting amount with 3 different water and sediment series, except for the Weilan?Weiyu 1 reach being silt, the other reaches of the river are accumulated sceour. The cumulative scour and silting amount in the lower Weihe river will be 83.8 millinn cubic meters,135.7 millions cubic meters and 167.1 million cubic meters under the rich water and sediment, less water and sediment, the present case respectively,which means that the lower Weihe river wil be the main trend of scour. (2) The scour amount in the Wiyu 1?10, Weiyu 10?26 and Weiyu 26?37 reach accounted for the lower reaches of Weihe river total scour amount, shows respectively as 34.99%?5.53%?59.48% under the rich uwater and sediment concditions, 23.86%?29.70%?46.43%under the less water and sediment conditions,and 27.78%?28.78%?43.43% under the present conditions. From the spatial distribution of the scour and silting amount with 3 different water and sediment series, the scour amount is mainly distributed in the Weiyu 26?37 reach. (3) In terms of the cumulative scour and silting amount in the lower Weihe river of different water and sediment series with time changes, series of the rich water and sediment being cumulative silting in 4?6 years,the other years are cumulative scour. However,series of less water and sediment and series of the present case are cumulative scour from the beginning to the end. (4)Under the different water and sediment conditions, the scour and silting amount will be different in the lower Weihe river, as the different in elevation amplitude of water level. For the scour amount is the largest in the Weiyu 26?37 reach,the descent range of flood level is also the largest in the different flow rate.