The Science of Surface and Ground Water NPTEL（地表水和地下水的NPTEL的科学）.pdf

Module 2 The Science of Surface and Ground Water Version 2 CE IIT, Kharagpur Lesson 8 Flow Dynamics in Open Channels and Rivers Version 2 CE IIT, Kharagpur Instructional Objectives On completion of this lesson, the student shall be able to learn: 1. The physical dynamics of water movement in open channels and rivers 2. The mathematical description of flow processes in the above cases 3. Different types of free surface flows: uniform, non uniform, etc. 4. Different channel shapes and cross sections and their representations 5. Computation steps for gradually varied water surface profiles 2.8.0 Introduction It is common for water resources engineers to design a water system involving flow of water from one place to another, usually passing a variety of structures on the way some of them meant for controlling the flow quantity. Rivers and artificial channels, like canals, convey water with a free surface, that is, the surface of water being exposed to air as opposed to flow of water in pipes. It is easy to visualize that for any such open channel flow, as they are called; the presence or absence of a hydraulic structure controls the position of the free surface of water. Knowing the mathematical description of flowing water, it is possible to compute the water surface profile, which is important for example in designing the height of the channel walls of the water conveying system. Another example, the case of river flow obstruction by the presence dam may be mentioned. The water level of t