Research On The Hydraulic Geometry Of The Canal

The modern ship hydrodynamic has continuously eroded the navigable canal’s boundary.With the effects of ship wave and water flow,the cross-section of navigable canal is adjusted to the equilibrium state.In this equilibrium state,there is a certain relationship between the cross-sectional shape,ship wave and river bed boundary,which is called the canal hydraulic geometry.The influence of the ship hydrodynamic fators on the canal morphology is rarely considered in the existing hydraulic geometry studies.Establishing the relationship between ship hydrodynamic factors and the cross-sectional shape and exploring the hydraulic geometry under the action of ship hydrodynamic can improve the existing theory of hydraulic geometry.It is also of significance to the construction and maintenance of the canal.In this paper,the hydraulic geometry of the canal is studied based on statistical law and the information entropy theory.The main research results are as follows,(1)The hydrodynamic characteristics and the characteristics of cross-sectional morphology evolution are analyzed taking part of the sections in Jiangsu segment of the Grand Canal.The relvent parameters are proposed which can be used to study the hydraulic geometry of the canal.The relevant parameters can be divided into two categories:ship hydrodynamic factors,including depth Froude number and Cross-section coefficient,and sectional morphology factors,including channel bottom width and average water depth under the designed lowest navigable water level.(2)The hydraulic geometry of the canal is established based on the statistical law.The relationship is suitable for the hydraulic evolution analysis when the river bed section tends to be in a relatively equilibrium state or has been in a relatively balanced state.There is a significant positive correlation between the hydraulic geometry and ship hydrodunamic factors.The ship hydrodynamic is the main factor affecting the evolution of the canal cross-section.(3)The time-varying formula of hydraulic geometry is established based on the information entropy theory.The influence parameters in the formula are discussed and the accuracy of the proposed formula is analyzed.Furthermore,this formula is used to predict the hydraulic geometry coefficient of the river bed section at any time and the equilibrium time.The predicted results are in good agreement with the actual situation.