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 Current Category » Micro Irrigation and Drainage Engineering Models Design of Drip Irrigation System Crop = Mango ( 5m X 5m) Area= 1 ha ( Assume square plot) Pan evaporation = 8 mm/day Pan coefficient = 0.7 Crop factor= 0.75 % wetted area= 60 Soil type= medium Water source is well at the corner of the field ( well depth) = 10m      Assume pump efficiency 70% and motor efficiency = 80% Solution: i) Determination of Water Requirement ( WR): WR= Crop area X PE X PC X KC X % wetted area        = 5m X 5m X 8 X0.7X 0.75 X 0.6        = 63 lit /day/ plant ii) Selection of Dripper: Selection 2 dripper of 8 lph capacity per plant Total no of plants = Total area                                  __________                                   Plant area                               = 10,000/ 5 X 5 = 400 No of drippers = 400 X 2 = 800 iii) Selection and Design of Lateral: Flow rate of lateral =  No of dripper on lateral X Discharge of drippers per plant. No of dripper on lateral = Length of Lateral                                         ____________________________                                           Spacing between two drippers                                        = 50/5                                        = 10 Q of lateral = 10X 2 X8 = 160 lit/hr Give the sub-main at the centre of the point Length of lateral = 50 m Diameter of lateral= 12 mm = 1.2 cm Head loss in lateral ∆H= 1.526 X 104 X (Q/C) 1.852 X D -4.871 X LX F Where, Q= Flow rate of lateral in m3 /hr C= Hazen and William constant D= Diameter of pipe in cm L= Length of pipe in m F= Outlet factor ∆H= 1.526 X 104 X (0.16/150) 1.852 X (1.2) -4.871 X 50 X 0.39 ∆H= 0.38 ∆ Head loss is less than 2 m , hence design is acceptable. iv) Selection and Design of Sub-main: Select 40 mm Sub- main. Select 40 mm mainline Flow rate of mainline= Flow rate of Submain Q= 6.4 m3 /hr Diameter of mainline = 4cm Diameter of mainline= 40mm=4cm. Head loss in Mainline, H= 1.526 X 104 X ( Q/C) 1.852 X D -4.871 X L X F    = 1.526 X 104 X  ( 6.4/150) 1.852 X (4) -4.871 X 100 So, H= 2.58m Selection Pump: Total discharge, Q=6.4 m3 /hr Q= 6400 lph Q = 6400 lps        ________ 1.77lps         60 X 60   Total head of pump = ( Suction head+ delivery head) + operating pressure of drip irrigation system+ filter loss + fitting loss + mainline loss + ventury loss + elevation difference Suction head + delivery head = 10 Operating pressure= 1 kg /cm2 or 10m Filter loss = 2m for sand filter + 2m for screen filter                  = 4m Ventury loss = 5m Fitting loss= 2m Main line loss= 2.58 Elevation difference = 2m So, Total head of pump = 10+10+4 + 2 +2.58 +5+2                                      = 35.5 m H.P of pump = Q ( lps) X H (m)                        _______________                          75 X 0.7 X 0.8 So, Pump efficiency and motor efficiency is given as 70% and 80% respectively. HP= 1.49 hp So, HP of Pump is 1.49 hp say 2 HP vi) Irrigation Time: Irrigation Time = Peak water requirement per plant                            ____________________________                         Discharge of dripper per plant                      = 63                       _____= 3.9 ( say 4 hours)                        2 X 8   So, Irrigation time required is 4 hrs.   Current Category » Micro Irrigation and Drainage Engineering