Lecture 1 Hydrology main Concept Basic terminologies

Hydrology Basic

1. CE-303 HYDRAULICS Lecturer Engr. Hazrat Amin Department of Civil Engineering, University of Engineering and Technology Peshawar, Jalozai campus

2. Introduction to Hydraulics Lecture-01

3. Objective: To enable students to learn fundamentals of hydraulic engineering, particularly related to open channel flow, flow through pipes, dam and river engineering Department of Civil Engineering, University of Engineering and Technology, Peshawar

4. ٱللَّهُ ٱلَّذِي خَلَقَ ٱلسَّمَٰوَٰتِ وَٱلأَرْضَ وَأَنزَلَ مِنَ ٱلسَّمَآءِ مَآءً فَأَخْرَجَ بِهِ مِنَ ٱلثَّمَرَاتِ رِزْقاً لَّكُمْ وَسَخَّرَ لَكُمُ ٱلْفُلْكَ لِتَجْرِيَ فِي ٱلْبَحْرِ بِأَمْرِهِ وَسَخَّرَ لَكُمُ ٱلأَنْهَارَ Allah then declared His divine Oneness, saying: (Allah is He Who created the heavens and the earth, and causeth water) rain (to descend from the sky, thereby producing) the rain brought forth (fruits) different kinds of fruit (as food for you) and for all other created beings, (and maketh the ships to be of service) subservient (unto you, that they) i.e. the ships (may run upon the sea at His command) by His permission and will , (and hath made of service) subservient (unto you the rivers) they flow wherever you want; Department of Civil Engineering, University of Engineering and Technology, Peshawar

5. Assessment Method Midterm: 20% Final Term: 50% Sessional Work: 30% 12% Quizzes, 18% Assignments, Department of Civil Engineering, University of Engineering and Technology, Peshawar

6. What is Open Channel Flow? Open-channel flows are those that are not entirely included within rigid boundaries; a part of the flow is in contract with nothing at all, just empty space (atmosphere). The surface of the flow thus formed is called a free surface, As the flow boundary is freely deformable, in contrast to the solid boundaries. The boundary conditions at the free surface of an open-channel flow are always that both the pressure and the shear stress are zero everywhere The flow in open channel is due to the action of gravity. Department of Civil Engineering, University of Engineering and Technology, Peshawar

7. What is Open Channel Flow? The flow in open channel is due to the action of gravity. The flow in a conduit may be open cannel flow or pipe flow Open Channel flow has open surface where the pipe flow has none. Open channel flow is subjected to atmospheric pressure. Department of Civil Engineering, University of Engineering and Technology, Peshawar

8. Difference between O.C.F and Pipe Flow In terms of hydrualics : The water level in the tubes are maintained by the pressure in the pipe at elevations represented by the so-called Hydraulic Grade Line (HGL). The pressure exerted by the water in each section of the pipe is indicated by the corresponding tube by the height of the water column above waterline of the pips. Total energy of the section is elevation Z of the pipe center line, the piezometric height y and the velocity head V 2 /2g. Where V = mean flow velocity. Department of Civil Engineering, University of Engineering and Technology, Peshawar

9. SOME TERMS RELATED TO OPEN CHANNELS Channel Section A cross section taken normal to the direction of flow is called a channel section. Depth of Flow Section ‘y’ It is the vertical distance of the lowest point of the channel section from the free surface. Depth of Flow Section ‘d’ It is the depth of flow normal to the direction of flow.   Stage ‘Z’ It is the vertical distance of free surface above a specified datum. Department of Civil Engineering, University of Engineering and Technology, Peshawar

10. SOME TERMS RELATED TO OPEN CHANNELS Flow Area ‘A’ It is cross-sectional area of flow normal to the direction of flow. Department of Civil Engineering, University of Engineering and Technology, Peshawar

11. SOME TERMS RELATED TO OPEN CHANNELS Wetted Perimeter ‘P’ It is the length of line of intersection of channel wetted surface with a cross-sectional plane normal to the flow direction. Hydraulic Radius ‘R’ It is the ratio of flow area to wetted perimeter, i.e., R=A/P. Top Width ‘B’ It is the width of the channel section at the free surface. Hydraulic Depth ‘D’ It is the ratio of flow area to top width, i.e., D=A/B. Normal Depth ‘y₀’ A depth at which the flow is uniform Department of Civil Engineering, University of Engineering and Technology, Peshawar

12. SOME TERMS RELATED TO OPEN CHANNELS HYDRAULIC GRADE LINE (HGL) A line joining the top of the liquid surface in the piezometers in a closed conduit or an open channel is called hydraulic grade line. In pipe flow, the height of HGL above a specified datum is called the piezometric head at that location. In free surface flow, the HGL usually, but not always, coincides with the free surface. Department of Civil Engineering, University of Engineering and Technology, Peshawar

13. SOME TERMS RELATED TO OPEN CHANNELS ENERGY GRADE LINE (EGL) If the velocity head is added to the top of the HGL and the resulting points are joined by a line, then this line is called energy grade line. EGL represents the total head at different sections of a closed conduit or an open channel. Department of Civil Engineering, University of Engineering and Technology, Peshawar

14. Kinds Of Open Channel Natural Channel Artificial Channel Department of Civil Engineering, University of Engineering and Technology, Peshawar

15. Kinds Of Open Channel Hydraulic properties of natural channels Irregular shapes (cross-sections) Diverse materials Surface roughness vary with time, distance and water level elevation Hydraulic theory difficult to apply Department of Civil Engineering, University of Engineering and Technology, Peshawar

16. Kinds Of Open Channel Artificial (man-made) channels are those constructed or developed by human efforts. They include: Irrigation canals Navigation channels Spillways Sewers Culverts drainage ditches Power canals Department of Civil Engineering, University of Engineering and Technology, Peshawar

17. TERMINOLOGY A channel may be natural or artificial. Various names have been used for artificial channels as follows: Canal A long channel having mild slope excavated in ground is called a canal.   Flume A channel supported above ground and built of wood, metal or concrete is called a flume.   Chute A chute is a channel having very steep bottom slope and almost vertical sides. Department of Civil Engineering, University of Engineering and Technology, Peshawar

18. TERMINOLOGY Tunnel A tunnel is a channel excavated through a hill or a mountain. Culvert A short channel flowing partly full is known as culvert.  Prismatic Channel A channel having the same cross section and bottom slope is referred to as a prismatic channel Non-Prismatic Channel A channel having varying cross section and/or bottom slope is called a non-prismatic channel. Department of Civil Engineering, University of Engineering and Technology, Peshawar

19. Channel Geometry

20. CLASSIFICATION OF FLOWS Department of Civil Engineering, University of Engineering and Technology, Peshawar

21. CLASSIFICATION OF FLOWS Department of Civil Engineering, University of Engineering and Technology, Peshawar STEADY AND UNSTEADY FLOWS If the flow velocity at a given point does not change with respect to time, then the flow is called steady flow. However, if the velocity at a given location changes with respect to time, then the flow is called unsteady flow. UNIFORM AND NON-UNIFORM FLOWS If the flow velocity at a given instant of time does not change within a given length of channel, then the flow is called uniform flow. However, if the flow velocity at a time varies with respect to distance, then the flow is called non-uniform flow or varied flow.

22. CLASSIFICATION OF FLOWS Department of Civil Engineering, University of Engineering and Technology, Peshawar GRADUALLY & RAPIDLY VARIED FLOW If the flow depth varies at a slow rate with respect to distance, then the flow is called gradually varied flow (GVF) whereas if the flow depth varies significantly in a short distance then the flow is called rapidly varied flow. LAMINAR AND TURBULENT FLOWS If the liquid particles appear to move in definite smooth paths and flow appears to be as a movement of thin layers on top of each other, then the flow is called laminar flow. In turbulent flow , the liquid particles move in irregular paths which are not fixed with respect to either time or space. The value of Reynolds number (R e =VL/  ) determines whether the flow is laminar or turbulent.

23. Velocity Distribution In A Channel Section

24. VELOCITY DISTRIBUTION Department of Civil Engineering, University of Engineering and Technology, Peshawar The flow velocity in a channel section varies from one point to another. This is due to shear stress at the bottom and the sides of the channel and due to the presence of free surface. Following figures show typical velocity distributions in different channel cross-sections.

25. Measurements Of Velocity According of stream-ganging procedure of the U.S Geologic survey, the channel cross-section is divided into vertical strips by a number of successive vertical, and mean velocities in vertical are determined by measuring the velocity at 0.6 of the depth of each vertical or where more reliable results are required by taking the average at 0.2 and 0.8 of the water depth. The average of mean velocities in any two adjacent vertical multiply by the area between the verticals gives the discharge through this vertical strip. Department of Civil Engineering, University of Engineering and Technology, Peshawar

26. End of Lecture No. 1 THANK YOU Department of Civil Engineering, University of Engineering and Technology, Peshawar

27. Department of Civil Engineering, University of Engineering and Technology, Peshawar