ES337 Water for Developing Countries Part B: Irrigation and Hydropower

2. Brett Martinson  Office F334 Office hours Monday 11:00 � 13:00 Phone 22339 E-mail dbm@eng.warwick.ac.uk

3. Objectives To illustrate the combination of economics, engineering and social organisation that determines the best choice between competing technologies for any specific site. To familiarise students with the design processes and the trade-offs required in selecting sites and system components for Hydropower. To enable students to design simple irrigation systems and choose between competing methods of water extraction. To introduce them to the complexity of the socio-technical interactions that constrain the construction of new irrigation or hydropower schemes.

4. Syllabus B1. Basics Hydrology, Water conveyance, Water storage B2. Hydro power Hydro systems, power needs, power available, yields and economics system design, entry arrangements, penstocks and surge control, turbine selection, exit arrangements and draft tubes, electronics and control B3. Irrigation Water needs, Irrigation types,

5. Books Massey, B (1998) Mechanics of Fluids Stanley Thornes (QC 211 M2) Harvey A et al (1993) Micro-hydro Design Manual, IT Pubs, (TK 1081 H2) Inversin, A ( 1986) Micro-Hydro Sourcebook, NRECA (TK 1081 I6) Tong Jiandong et al (1997) Mini Hydropower, Wiley, (TK 1081 M4) Stern, P (1997) Small Scale Irrigation IT Pubs (TC 805 S8) Cornish G (1998) Modern Irrigation Technologies, IT Pubs, (qto TC 805.C6) Diemer G & Huibers F (1996) Crops, People & Irrigation IT Pubs (S 613 C7)

6. Web resources Course site www2.warwick.ac.uk/fac/sci/eng/staff/dbm/es337/ Dams World Commission on Dams (home of Dams and Development: A New Framework for Decision-Making) http://www.dams.org Hydro www.microhydropower.net Irrigation FAO Irrigation Water Management Training Manuals www.fao.org/docrep/

7. Assessment Exam (70%) Three of six questions (choose four) Assessed work (30%) Set in week 14 Worth 2.25 CATS (? 22 � hours work)

9. B1.1 HydrologyTopics Catchments Runoff coefficient Infiltration, rainfall runoff relations, runoff coefficients Interpolating rainfall data Arithmetic mean method,Thiessen networks, isohyets Flow measurement Buckets, staff gauge, weirs, current meters, salt gulp, float method Flow frequency

10. B1.1.1 HydrologyCatchments

11. B1.1.1 HydrologyCatchments: Estimating area: Counting squares

12. B1.1.1 HydrologyCatchments: Estimating area: Blocking

13. B1.1.2 HydrologyRunoff:Components

14. B1.1.2 HydrologyRunoff:Components

15. B1.1.2 HydrologyRunoff:Components Transpiration Water used by plants and returned to the atmosphere Evaporation Water evaporated directly from surface puddles Soil water Water retained by the soil Overland flow water running on the surface Interflow Water flowing underground but feeding the water course Groundwater accreditation Water lost to groundwater

16. B1.1.2 HydrologyRunoff:Infiltration

17. B1.1.2 HydrologyRunoff:Infiltration

18. B1.1.2 HydrologyRunoff:Coefficient

19. B1.1.2 HydrologyRunoff:Coefficients

20. B1.1.2 Hydrology Streamflow

21. B1.1.3 HydrologySpatial interpolation of rainfall data

22. B1.1.3 HydrologySpatial interpolation: Arithmetic mean Average each station in the area

23. B1.1.3 HydrologySpatial interpolation: Arithmetic mean: Limitations Quick and dirty Takes no account of changes in rain gauge density � outlying, unrepresentative gauges can be over valued Not applicable if rainfall is dominated by topography, intense convection or very localised rainfall

24. B1.1.3 HydrologySpatial interpolation

25. B1.1.3 HydrologySpatial interpolation: Thiessen method

26. B1.1.3 HydrologySpatial interpolation: Thiessen method

27. B1.1.3 HydrologySpatial interpolation: Thiessen method

28. B1.1.3 HydrologySpatial interpolation: Thiessen method

29. B1.1.3 HydrologySpatial interpolation: Thiessen method

30. B1.1.3 HydrologySpatial interpolation: Thiessen method: Limitations Not applicable if rainfall is dominated by topography, intense convection or very localised rainfall Can be unnecessarily time consuming as catchment becomes smaller and rain gauges are more spaced out � simple distance weighting may be adequate

31. B1.1.3 HydrologySpatial interpolation: Isohyets

32. B1.1.3 HydrologySpatial interpolation: Isohyets: Limitations Not applicable if rainfall is dominated by topography or intense convection (but better than Thiessen) Often difficult to obtain in low-income countries and usually only for average yearly precipitation

33. B1.1.4 HydrologyFlow estimation Buckets Float Weirs Staff gauge Current meters Salt gulp

34. B1.1.4 HydrologyFlow estimation: Buckets

35. B1.1.4 HydrologyFlow estimation: Buckets: Limitations Only useful for flows <20l/s Whole flow must be channelled to the bucket

36. B1.1.4 HydrologyFlow estimation: Float

37. B1.1.4 HydrologyFlow estimation: Float: Limitations Average flow can only be inferred from flow at surface The stream bed should not have any significant changes over the test length Needs a good approximation of the stream bed shape � which can be tedious

38. B1.1.4 HydrologyFlow estimation: Float: Correction factors

39. B1.1.4 HydrologyFlow estimation: Weirs

40. B1.1.4 HydrologyFlow estimation: Weirs: Calculation for rectangular weirs Proof in Massey p105-109Proof in Massey p105-109

41. B1.1.4 HydrologyFlow estimation: Weirs: Calculation: Weir coefficients for rectangular weirs Proof in Massey p105-109Proof in Massey p105-109

42. B1.1.4 HydrologyFlow estimation: Weirs: Calculation for triangular weirs Proof in Massey p105-109Proof in Massey p105-109

43. B1.1.4 HydrologyFlow estimation: Weirs: Calculation: Weir coefficients for triangular weirs Proof in Massey p105-109Proof in Massey p105-109

44. B1.1.4 HydrologyFlow estimation: Weirs: Limitations An initial flow estimate is required to ensure the notch is an appropriate size The weir must be perfectly sealed Permanent weirs are costly Even a temporary weir can be problematic and time consuming to construct

45. B1.1.4 HydrologyFlow estimation: Staff gauge

46. B1.1.4 HydrologyFlow estimation: Staff gauge: Limitations Needs a good approximation of the stream bed shape which must remain valid � erosion/siltation will effect the validity of measurements Only valid for comparing flows over time � an initial flow reading must be taken by another method �weir coefficients� will change with water height

47. B1.1.4 HydrologyFlow estimation: Current meters

48. B1.1.4 HydrologyFlow estimation: Current meters: Limitations Needs a good approximation of the stream bed shape Cost? Fragility?

49. B1.1.4 HydrologyFlow estimation: Salt gulp

50. B1.1.4 HydrologyFlow estimation: Salt gulp

51. B1.1.4 HydrologyFlow estimation: Salt gulp

52. B1.1.4 HydrologyFlow estimation: Salt gulp: Problems

53. B1.1.4 HydrologyFlow estimation: Salt gulp: Limitations Automated equipment can be expensive � non automated procedure is complex Needs skill to take readings and interpret duff ones Errors may not be apparent unless maths is done on-site

54. B1.1.5 HydrologyFlow frequency: Time series

55. B1.1.5 HydrologyFlow frequency: Mass curve (Rippl diagram)

56. B1.1.5 HydrologyFlow frequency: Buckets

57. B1.1.5 HydrologyFlow frequency: Exceedance (flow duration curve)

58. B1.1.5 HydrologyFlow frequency: Exceedance (flow duration curve)

59. B1.1 HydrologySummary Streams are defined by their �catchments�; the area where rain falls and flows to the stream Rainfall over a catchment can be converted to a (fairly rough) estimate of streamflow by using a runoff coefficient Nearby rain gauges can be used to give an estimate of the rainfall over a catchment using arithmetic mean or Thiessen methods. Isohyets can also be used Streamflow can also be measured directly using means of buckets, floats, weirs, staff gauges current meters and the salt gulp technique Time series data can usefully be summarised as a mass curve or as an exceedance

60. B1.2 Next�..Water Storage