1. HYDRAULICS_2 Design of Irrigation Systems by László Ormos

2. Total Head by Bernoulli’s Law where the relative elevation of the water; the pressure head of the water; the water velocity head.

3. Energy Head Loss in Pipes The energy loss (head loss) in pipes due to water flow (friction) is proportional to the length of pipe:, where J is the head loss in a pipe expressed by either % or ‰.

4. Energy Head Loss in Pipes The head loss due to friction is found out by the Hazen Williams expression: where J is the head loss expressed by ‰, Q is the flow rate expressed by m 3 /hr, vis the flow velocity by m/sec, Dis the diameter of pipe expressed by mm, Cis the smoothness of internal surface of pipe.

5. Energy Head Loss in Pipes The layout of an irrigation system is the following: The flow rate of pump at A is Q A =300m 3 /h at p A =6 bar pressure. The water flow rate out of B is Q B =200m 3 /h. What are pressures at the points B and C? L1=900m L2=200m D1=250mm D2=150mm A (h A =172m) B (h B =196m) C (h C =180m) QBQB QAQA

6. Energy Head Loss in Pipes For A-B: the head loss due to a friction for the D1=250mm pipe (C=130) and Q=300m 3 /h can be found out of tables or slide ruler. The hydraulic gradient is J=11‰. 1.The actual head loss due to a friction for L1=900m long pipe is: 2.The difference elevation between A to B is: 3.Water pressure at point B is:

7. Energy Head Loss in Pipes For B-C: the head loss due to a friction for the D2=150mm pipe (C=130) and Q=100m 3 /h can be found out of tables or slide ruler. The hydraulic gradient is J=18‰. 4.The actual head loss due to a friction for L2=200m long pipe is: 5.The difference elevation between B to C is: 6.The water pressure at point C is:

8. Energy Head Loss in Pipes The result can also be computed by Bernoulli’s law for B and C only as follows: 7.Water flow velocity in 250mm pipe is the following:

9. Energy Head Loss in Pipes 8.Water flow velocity in 150mm pipe is the following:

10. Energy Head Loss in Pipes 9.The difference head velocity is: 10.Water velocity heads are as follows:

11. Energy Head Loss in Pipes 11.Water pressure at point C is: (since the difference velocity head  h v has been too small it can be neglected)

12. Energy Head Loss in Pipes Given a 300 meters long pipe and its diameter is 250mm (C=130) which connects a cistern (A) at elevation of 30m to a booster (B) at a sea level, and from there to a cistern 2200m away at elevation of 180m. The booster pump generates 17bar pressure. What is the flow rate? A H A =30m L AB =300m C B(booster) H C =180m L BC =2200m

13. Energy Head Loss in Pipes 1.The water pressure just before the booster is as follows: 2.The water pressure just after the booster is as follows: 3.For B-C section

14. Energy Head Loss in Pipes 4.The total pipe length is 5.The head loss due to the friction is as follows: The water flow rate can be found out of tables or a slide ruler based on J=8[‰] and D=250[mm]. It is about 250[m 3 /h].

15. References Azenkot, A.(1998):”Design Irrigation System”. Ministry of Agricul- ture Extension Service (Irrigation Field service), MASHAV Israel Dr. Avidan, A.(1995):”Soil-Water-Plant Relationship”. Ministry of Agriculture Extension Service (Irrigation Field service), CINADCO, Ministry of Foreign Affairs, MASHAV, Israel Sapir, E.-Dr. E. Yagev (1995):”Drip Irrigation”. Ministry of Agricul- ture and Rural Development, CINADCO, Ministry of Foreign Affairs, MASHAV, Israel Sapir, E.-Dr. E. Yagev (2001):”Sprinkler Irrigation”. Ministry of - culture and Rural Development, CINADCO,Ministry of Foreign Affairs, MASHAV, Israel Eng. Nathan, R. (2002):”Fertilization Combined with Irrigation (Fertigation)”. Ministry of Agriculture and Rural Development, CINADCO,Ministry of Foreign Affairs, MASHAV, Israel