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1 Part B3: Irrigation B3.1 Irrigation techniques.

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Presentation on theme: "1 Part B3: Irrigation B3.1 Irrigation techniques."— Presentation transcript:

1 1 Part B3: Irrigation B3.1 Irrigation techniques

2 2 B3.2Irrigation techniques Topics Surface irrigation –Basin irrigation, border irrigation, furrow irrigation Rainwater harvesting –Bunds, microcatchments, “Modern” irrigation techniques –Spray irrigation, micro irrigation

3 3 B3.2.1Irrigation techniques Surface irrigation: Flow

4 4

5 5 B3.2.1Irrigation techniques Surface irrigation: Inlet arrangements

6 6

7 7

8 8 T f = Time to reach the opposite end of the field (hr) T a = Application time (hr) B3.1.4Fundamentals of irrigation Surface irrigation: The quarter time rule

9 9 B3.2.1Irrigation techniques Surface irrigation: Basin irrigation

10 10 B3.2.1Irrigation techniques Surface irrigation: Flow

11 11 B3.2.1Irrigation techniques Surface irrigation: Basin irrigation

12 12 B3.2.1Irrigation techniques Surface irrigation: Basin irrigation: Scaling

13 13 B3.1.4Fundamentals of irrigation Surface irrigation: Basin irrigation: Scaling Stream size (l/s)SandSandy loam Clay loamClay

14 14 B3.2.1Irrigation techniques Surface irrigation: Basin irrigation: Problems

15 15 B3.2.1Irrigation techniques Surface irrigation: Basin irrigation: Terracing

16 16 B3.2.1Irrigation techniques Surface irrigation: Border irrigation

17 17 B3.2.1Irrigation techniques Surface irrigation: Border irrigation

18 18 B3.2.1Irrigation techniques Surface irrigation: Border irrigation

19 19 B3.2.1Irrigation techniques Surface irrigation: Border irrigation: Scaling

20 20 B3.2.1Irrigation techniques Surface irrigation: Border irrigation: Scaling Soil typeIrrigation depth (mm) Slope (%) Width (m) Length (m) Unit stream (l/s/m) Sand Sand Sand

21 21 Soil typeHumid areasArid areas Bare soilGood crop cover Bare soilGood crop cover Sand Clay B3.2.1Irrigation techniques Surface irrigation: Border irrigation: Scaling

22 22 B3.2.1Irrigation techniques Surface irrigation: Border irrigation: Problems

23 23 B3.2.1Irrigation techniques Surface irrigation: Border irrigation: Problems

24 24 B3.2.1Irrigation techniques Surface irrigation: Furrow irrigation

25 25 B3.2.1Irrigation techniques Surface irrigation: Furrow irrigation

26 26 B3.2.1Irrigation techniques Surface irrigation: Furrow irrigation

27 27 B3.2.1Irrigation techniques Surface irrigation: Furrow irrigation

28 28 B3.2.1Irrigation techniques Surface irrigation: Furrow irrigation

29 29 B3.2.1Irrigation techniques Surface irrigation: Furrow irrigation: Infiltration

30 30 B3.2.1Irrigation techniques Surface irrigation: Furrow irrigation: Scaling

31 31 B3.2.1Irrigation techniques Surface irrigation: Furrow irrigation: Scaling Slope (%) Max stream size (l/s) Average irrigation depth (mm) ClayLoamSand

32 32 B3.2.1Irrigation techniques Surface irrigation: Furrow irrigation

33 33 B3.2.1Irrigation techniques Surface irrigation: Furrow irrigation: problems

34 34 B3.2.2Irrigation techniques Rainwater harvesting The collection and concentration of runoff Sits between rain-fed agriculture and traditional irrigation –Can produce a crop where none is possible with simple rain catchment Usually in arid and semi-arid areas but also suited to semi tropical Rainwater is purer than ground or surface water – salinity

35 35 B3.2.2Irrigation techniques Rainwater harvesting:

36 36 B3.2.2Irrigation techniques Rainwater harvesting Production costs Cash crops/income Yields Salinity hazard Reliability Rain fed agriculture Rainwater harvesting Irrigated agriculture

37 37 B3.2.2Irrigation techniques Rainwater harvesting: limitations Climatic fluctuations –Yields cannot be guaranteed Potential up and downstream conflict (but less than “traditional” irrigation Some scientific uncertainty Large schemes difficult to implement

38 38 B3.2.2Irrigation techniques Rainwater harvesting

39 39 C = Catchment Ca = Cultivated area ET cr = Crop evapotranspiration P = Design rainfall k = Runoff coefficient  = Efficiency B3.2.2Irrigation techniques Rainwater harvesting: Catchment – cultivated area ratio (C:Ca)

40 40 B3.2.2Irrigation techniques Rainwater harvesting: Efficiency

41 41 B3.2.2Irrigation techniques Rainwater harvesting: Design Rainfall: curve

42 42 B3.2.2Irrigation techniques Rainwater harvesting: Design Rainfall: Exceedance table JanFeb.MarAprMayJunJulAugSepOctNovDec 10% % % % % % % % % %

43 43 B3.2.2Irrigation techniques Rainwater harvesting: Microcatchments Small (thus the name) m 2 Catchment and cropping areas adjacent Crops are usually a single tree/catchment or small annual crop No overflow Small area ratio (1:1 – 10:1) Tend to be in series of units Efficiency

44 44 B3.2.2Irrigation techniques Rainwater harvesting: Microcatchments

45 45 B3.2.2Irrigation techniques Rainwater harvesting: Microcatchments: Negarims

46 46 B3.2.2Irrigation techniques Rainwater harvesting: Microcatchments: Negarims

47 47 B3.2.2Irrigation techniques Rainwater harvesting: Microcatchments: Negarims

48 48 B3.2.2Irrigation techniques Rainwater harvesting: Microcatchments: Semi circular bunds

49 49 B3.2.2Irrigation techniques Rainwater harvesting: Microcatchments: Semi circular bunds

50 50 B3.2.2Irrigation techniques Rainwater harvesting: Microcatchments: Semi circular bunds

51 51 B3.2.2Irrigation techniques Rainwater harvesting: Microcatchments: Semi circular bunds

52 52 B3.2.2Irrigation techniques Rainwater harvesting: Microcatchments: Contour bunds

53 53 B3.2.2Irrigation techniques Rainwater harvesting: Microcatchments: Contour bunds

54 54 B3.2.2Irrigation techniques Rainwater harvesting: Macrocatchments Big ,000m 2 Used for all types of crops Often includes overflow structures larger area ratio (10:1– 100:1) Efficiency

55 55 B3.2.2Irrigation techniques Rainwater harvesting: Macrocatchments Stone bunds

56 56 B3.2.2Irrigation techniques Rainwater harvesting: Macrocatchments Stone bunds

57 57 B3.2.2Irrigation techniques Rainwater harvesting: Macrocatchments Stone bunds

58 58 B3.2.2Irrigation techniques Rainwater harvesting: Macrocatchments: Hillside conduits

59 59 B3.2.2Irrigation techniques Rainwater harvesting: Macrocatchments: Hillside conduits

60 60 B3.2.2Irrigation techniques Rainwater harvesting: Macrocatchments: Hillside conduits

61 61 B3.2.2Irrigation techniques Rainwater harvesting: Macrocatchments: Hillside conduits

62 62 B3.2.2Irrigation techniques Rainwater harvesting: Floodwater harvesting Can be diverted to conventional-style irrigation or microcatchments Variable size Ha – km 2 Used for all types of crops Variable area ratio (1:1– 10,000:1)

63 63 B3.2.2Irrigation techniques Rainwater harvesting: Floodwater harvesting (water spreading)

64 64 B3.2.2Irrigation techniques Rainwater harvesting: Floodwater harvesting (water spreading)


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