Irrigation: crops and water delivery  Irrigation and  Drainage  CT4410  Maurits Ertsen                                    ...
Nevada Irrigation DistrictDecember 14, 2011            2
Nevada                    Irrigation                    DistrictDecember 14, 2011                3
A little history of NIDDecember 14, 2011         4
Transforming a ditch for mines to aditch for irrigation• High canals• Continuous flow• Reservoirs• Water measurement in NI...
The system   December 14, 2011   6
Water measurement                       • The miners inch                       • Amount of water flowing                 ...
Controlling the canal• What if a farmer does not  needs his water?• How to keep the constant  head?     December 14, 2011 ...
December 14, 2011   9
December 14, 2011   10
December 14, 2011   11
Water requirements• How to determine water  requirements?• How to predict water demand?    December 14, 2011            12
Design problemWhat cropping pattern do you take?How correct is the ET calculation?How correct is the ET and rainfall for t...
How to irrigate crops?• Pressurized systemDecember 14, 2011        14
Blue beans                                                             Start 1/1                                          ...
Climate                        Rain      ETo                      mm/stage   mm/day                                       ...
How to distribute that?   Flow for a farm of one          hectare                            mm/day     m3/s        l/s Co...
Your assignment1. Calculate total water demand for a 1000 hectare area in   the NID over a year.2. Describe how this water...
Example information                                Trees                    35%    of total area      Start 1/4           ...
December 14, 2011   20
First, a little warning: physical realityneededDecember 14, 2011                       21
December 14, 2011   22
December 14, 2011   23
December 14, 2011   24
December 14, 2011   25
What did I do? Water requirements          10           8           6           4           2           0          -2     ...
Water need in l/s and miners inches/farm 80 60 40 20  0 -20 -40 -60 -80-100       December 14, 2011                       ...
So why start per April 1??• What if a farmer is an early vegetable grower?• What if it does not rain in April?• What if … ...
Canal calculationNot that straightforward designing a fitting canal and structures canal               AB L               ...
Canal calculation So probably we need water level controls somewhere. Weirs? Spills? How many? Dimensions?   December 14, ...
December 14, 2011   31
And what if I have farmers with onlyfuit and vegetables????         8         7         6         5         4         3   ...
What did I do?  Design discharge of 1 m3/s  Water depth of 1 meter, bed width of 2 meters  Slope of 1 in 10000  Side slope...
Result with inflow and all outlets are                    open.                    NO LEVEL CONTROLDecember 14, 2011      ...
LEVEL CONTROL WITH WEIR             But as discharges downstream are very low             and as there is no flow over the...
LEVEL CONTROL WITH WEIR             With extra discharge, there is flow over the             weir.             Now it woul...
Structures as the keyof a system. ExampleElche, SpainMaurits Willem ErtsenDelft University of Technology14-12-2011        ...
Third largest city of theAutonomous Community ofValencia, SpainSome 200,000 inhabitantsIrrigated agricultureHuertasElche P...
Landscape
Watersources
Canal system
Canals
Canals
Walking along    the water
Walking further along            the water
Canals
What is  irrigation  about?A structure asexpression ofwater rights.Remember?
Irrigation: main system layout                                 1  Water Resources Management
Ordering the disorder?                                    Goal:  • You know water demand and water smallest unit          ...
Main issues• Layout of the main system       • Every canal above tertiary units       • Determined by natural terrain and ...
Layout                  1          2     3   4   5   6   7   8   9   10   km       (contour lines in meters)    December 1...
Layout                  1          2     3   4   5   6   7   8   9   10   km       (contour lines in meters)    December 1...
Capacities                   Q is known  Q at a certain level is                    Is total Q                    known???...
Capacities: example 1         1,2          1         0,8l/s/ha         0,6         0,4                         Proportiona...
Capacities: example 2             2,5              2             1,5    l/s/ha              1                             ...
Capacities: example 3            3,5             3            2,5                     Higher potential             2      ...
Capacities of the drainage systemLoads on the system: rainfall of 100 mm in 2 hours• Assuming an irrigated area of 5000 he...
Drainage capacities: decision time• The load: how often does it occur? Probability?• Design a drainage canal for a certain...
Three rainfall scenarios• Rainfall is showers (about every 10 to 15 days)• Rainfall averaged over all the days• Rainfall i...
Rain in showers         120                                                                                               ...
Showers plus maximum       120                                                                                            ...
Average          120                                                                             3.5                      ...
And the runoff??              70              60              50              40         mm              30              2...
La                        Unit 1ayo                                       Unit 1but                              Unit 2a  ...
Water levels in the system??                                          + 12 m                       + 13 m                 ...
Thus required water levels are:         16         15         14         13         12         11         10          9   ...
Remember your NID task????      Design a canal (calculate) and determine control structures for offtakes/canal. Each offta...
Your own designIssue 1: Water demand versus water availability   • Timing of the demand   • Timing of availability   • Amo...
Dimensioning your irrigation system• Take a typical stretch of your system• Determine required water levels along this str...
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CT4410: Requirement and delivery

  1. 1. Irrigation: crops and water delivery Irrigation and Drainage CT4410 Maurits Ertsen 1 Water Resources Management
  2. 2. Nevada Irrigation DistrictDecember 14, 2011 2
  3. 3. Nevada Irrigation DistrictDecember 14, 2011 3
  4. 4. A little history of NIDDecember 14, 2011 4
  5. 5. Transforming a ditch for mines to aditch for irrigation• High canals• Continuous flow• Reservoirs• Water measurement in NIDDecember 14, 2011 5
  6. 6. The system December 14, 2011 6
  7. 7. Water measurement • The miners inch • Amount of water flowing through a surface of one square inch with a head of six inches. • How many liters per second?? December 14, 2011 7
  8. 8. Controlling the canal• What if a farmer does not needs his water?• How to keep the constant head? December 14, 2011 8
  9. 9. December 14, 2011 9
  10. 10. December 14, 2011 10
  11. 11. December 14, 2011 11
  12. 12. Water requirements• How to determine water requirements?• How to predict water demand? December 14, 2011 12
  13. 13. Design problemWhat cropping pattern do you take?How correct is the ET calculation?How correct is the ET and rainfall for the entire area?How would you take into account “real” soil processes? In other words: how to take into account heterogeneity? Lankford (2004) discusses this. How to use remotely sensed ET in DESIGN ??December 14, 2011 13
  14. 14. How to irrigate crops?• Pressurized systemDecember 14, 2011 14
  15. 15. Blue beans Start 1/1 Crop Growth stage Length coefficient Root depth Days Meter Initial 90 0.5 2 Development 90 >> Mid 90 1.2 2 Late 95 0.8 2 365 1.4 1.2Crop water 1requirement Crop coefficient 0.8calculation: 0.6example 0.4 0.2 December 14, 2011 15 0 0 50 100 150 200 250 300 350 400 Days
  16. 16. Climate Rain ETo mm/stage mm/day Remarks: Initial 90 5 Assuming all rain is effective Development 65 6 Mid 40 7 Simplifying development stage Late 80 5 Significant numbers?? CRW mm/day Rain Eto kc Etg Etn Initial 1.00 5 0.5 2.5 1.50 Development 0.72 6 0.85 5.1 4.38 Mid 0.44 7 1.2 8.4 7.96 Late 0.84 5 0.8 4 3.16 December 14, 2011 16
  17. 17. How to distribute that? Flow for a farm of one hectare mm/day m3/s l/s Continuous 8 0.0009259 1 Continuous during day 8 0.0018519 2 Every week for 10 hours 8 0.0155556 16 Every week for 1 hour 8 0.1555556 156 Every month for 1 hour 8 0.6666667 6671. Suppose I have 10 farms, how much should my canal carry?2. Suppose I have 1200 l/s, how many farms can irrigate at the same time?3. In case 2, how large would my surface area per canal become? December 14, 2011 17
  18. 18. Your assignment1. Calculate total water demand for a 1000 hectare area in the NID over a year.2. Describe how this water would be supplied within the NID water delivery philosophy.3. Calculate required canal flows at the intake for this 1000 hectare area.4. Design the canal and outlets for this area, assuming that 20 farmers with each 50 hectares take water. Assume the canal being 10 kilometers long, with farm intakes evenly spread on one side. December 14, 2011 18
  19. 19. Example information Trees 35% of total area Start 1/4 Growth stage Length Crop coefficient Root depth Days Meter Initial 140 0.9 2 Development 30 >> Mid 150 0.95 2 Late 45 0.9 2 365 C r o p c oe f f i c i e n t T r e e s 1.20 1.00 0.80 0.60 0.40 0.20 Kc 0.00 0 December 14, 2011 50 100 150 200 250 300 19350 Days
  20. 20. December 14, 2011 20
  21. 21. First, a little warning: physical realityneededDecember 14, 2011 21
  22. 22. December 14, 2011 22
  23. 23. December 14, 2011 23
  24. 24. December 14, 2011 24
  25. 25. December 14, 2011 25
  26. 26. What did I do? Water requirements 10 8 6 4 2 0 -2 -4 -6 mm/day -8 1 31 61 91 121 151 181 211 241 271 301 331 361 days ET crops Rain ET net December 14, 2011 26
  27. 27. Water need in l/s and miners inches/farm 80 60 40 20 0 -20 -40 -60 -80-100 December 14, 2011 27 1 31 61 91 121 151 181 211 241 271 301 331 361 Flow in l/s/10 Miners inch per farm
  28. 28. So why start per April 1??• What if a farmer is an early vegetable grower?• What if it does not rain in April?• What if … ?And the canal? I know I will have fluctuating flows and that there is a need to maintain the same water level. So, one uniform flow calculation will not suffice. And I probably need some kind of water level control, and perhaps some spills.December 14, 2011 28
  29. 29. Canal calculationNot that straightforward designing a fitting canal and structures canal AB L 10000 Q increases: Q decreases: H control 0.64 canal AB canal AB y 0.64 L 10000 L 10000 H control 0.71 H control 0.47 A 2.97 y 0.71 y 0.47 Q 0.66 A 3.34 A 2.10 m 1 Q 0.8 Q 0.4 v 0.22 m 1 m 1 v 0.24 v 0.19 R 0.51 R 0.56 R 0.39 s 0.0001 s 0.0001 s 0.0001 k 35 k 35 k 35 b 4 b 4 b 4 n 5.6 n 8.5 n 6.3 December 14, 2011 29
  30. 30. Canal calculation So probably we need water level controls somewhere. Weirs? Spills? How many? Dimensions? December 14, 2011 30
  31. 31. December 14, 2011 31
  32. 32. And what if I have farmers with onlyfuit and vegetables???? 8 7 6 5 4 3 2 1mm/day 0 December 14, 2011 32 1 31 61 91 121 151 181 211 241 271 301 331 361 Days ET average ET fr and veg
  33. 33. What did I do? Design discharge of 1 m3/s Water depth of 1 meter, bed width of 2 meters Slope of 1 in 10000 Side slope of 1 Roughness of about 45 (Strickler)December 14, 2011 33
  34. 34. Result with inflow and all outlets are open. NO LEVEL CONTROLDecember 14, 2011 34
  35. 35. LEVEL CONTROL WITH WEIR But as discharges downstream are very low and as there is no flow over the weir, no real improvement.December 14, 2011 35
  36. 36. LEVEL CONTROL WITH WEIR With extra discharge, there is flow over the weir. Now it would be a matter of optimization…December 14, 2011 36
  37. 37. Structures as the keyof a system. ExampleElche, SpainMaurits Willem ErtsenDelft University of Technology14-12-2011 Delft University of Technology Challenge the future
  38. 38. Third largest city of theAutonomous Community ofValencia, SpainSome 200,000 inhabitantsIrrigated agricultureHuertasElche Palmeral: a little over 500hectares (about 5,000,000 m2)
  39. 39. Landscape
  40. 40. Watersources
  41. 41. Canal system
  42. 42. Canals
  43. 43. Canals
  44. 44. Walking along the water
  45. 45. Walking further along the water
  46. 46. Canals
  47. 47. What is irrigation about?A structure asexpression ofwater rights.Remember?
  48. 48. Irrigation: main system layout 1 Water Resources Management
  49. 49. Ordering the disorder? Goal: • You know water demand and water smallest unit availability • Therefore you know the potential area Goal: • You know the smallest unit you have to deliver smallest unit water to ??? • You know how you want to deliver water Goal: • You have ideas about structures to smallest unit be appliedSource: river Goal: • It’s time for the canals! smallest unit December 14, 2011 2
  50. 50. Main issues• Layout of the main system • Every canal above tertiary units • Determined by natural terrain and units• Capacities of main system • Losses • Rotation • Statistics• Behavior of the main system • Hydraulic flexibility • Operational flexibility • Reaction timesDecember 14, 2011 3
  51. 51. Layout 1 2 3 4 5 6 7 8 9 10 km (contour lines in meters) December 14, 2011 4
  52. 52. Layout 1 2 3 4 5 6 7 8 9 10 km (contour lines in meters) December 14, 2011 5
  53. 53. Capacities Q is known Q at a certain level is Is total Q known??? not necessarily the sum of all Q’s at lowerResults in a Q here levels. But here???? December 14, 2011 6
  54. 54. Capacities: example 1 1,2 1 0,8l/s/ha 0,6 0,4 Proportional 0,2 0 1 10 25 50 150 500 1000 1500 5000 HectaresDecember 14, 2011 7
  55. 55. Capacities: example 2 2,5 2 1,5 l/s/ha 1 Proportional, 0,5 taking into 0 account losses 1 10 25 50 150 500 1000 1500 5000 HectaresDecember 14, 2011 8
  56. 56. Capacities: example 3 3,5 3 2,5 Higher potential 2 demands on l/s/ha 1,5 1 lower levels 0,5 0 1 367 732 1097 1462 1828 2193 2558 2923 3289 3654 4019 4384 4750 HectaresDecember 14, 2011 9
  57. 57. Capacities of the drainage systemLoads on the system: rainfall of 100 mm in 2 hours• Assuming an irrigated area of 5000 hectares, this would give a volume of 5,000,000 m3But: how to discharge this volume?• In 2 hours: 694 m3/s• In 5 days: about 6 m3/s• Water will be stored in the system: on the fields, in the canals, in the soil (?)December 14, 2011 10
  58. 58. Drainage capacities: decision time• The load: how often does it occur? Probability?• Design a drainage canal for a certain maximum Q with freeboard, and allow a higher Q at times (without freeboard)?• Need to drain the irrigation supply? For example when nobody wants to irrigate?• Furthermore: like with supply canals, the sum of the Like with all individual canals does not have to be the same as the demand for peak maximum drainage discharge capacity. soil preparation! In short: enough to decide. Again…… December 14, 2011 11
  59. 59. Three rainfall scenarios• Rainfall is showers (about every 10 to 15 days)• Rainfall averaged over all the days• Rainfall in showers with maximum shower at 100 mm/day• All other parameters equal • Irrigation at 100 mm per 10 days • Silty loam • Initial groundwater at 3 meter below surfaceDecember 14, 2011 12
  60. 60. Rain in showers 120 3.5 3 100 2.5 80 2 mm m 60 1.5 40 1 20 0.5 0 0 1 21 41 61 81 101 121 141 161 181 201 221 241 261 281 301 321 341 361 Days Rain Irrigation Groundwater December 14, 2011 13
  61. 61. Showers plus maximum 120 3.5 3 100 2.5 80 2 mm 60 1.5 40 1 20 0.5 0 0 1 21 41 61 81 101 121 141 161 181 201 221 241 261 281 301 321 341 361 days Rainfall Irrigation Groundwater December 14, 2011 14
  62. 62. Average 120 3.5 3 100 2.5 80 2 mm m 60 1.5 40 1 20 0.5 0 0 1 21 41 61 81 101 121 141 161 181 201 221 241 261 281 301 321 341 361 days Rain Irrigation Groundwater December 14, 2011 15
  63. 63. And the runoff?? 70 60 50 40 mm 30 20 10 0 1 20 39 58 77 96 115 134 153 172 191 210 229 248 267 286 305 324 343 362 days Average Showers Showers maximum December 14, 2011 16
  64. 64. La Unit 1ayo Unit 1but Unit 2a Unit 2b December 14, 2011 17
  65. 65. Water levels in the system?? + 12 m + 13 m + 12 + 0.20 + 0.15 + 0.20 = + 9.5 m 12.55 m+ 13 + 0.20 + + 10.4 m0.20 + 0.20 =13.6 m + 10.4 + 0.20 + 0.20 + 0.20 = 11 m + 15 m December 14, 2011 18
  66. 66. Thus required water levels are: 16 15 14 13 12 11 10 9 8 0 1000 2000 3000 4000 5000 6000December 14, 2011 19
  67. 67. Remember your NID task???? Design a canal (calculate) and determine control structures for offtakes/canal. Each offtake requires 1 m3/s in the peak season and may need less or nothing during the remaining months.December 14, 2011 20
  68. 68. Your own designIssue 1: Water demand versus water availability • Timing of the demand • Timing of availability • Amount of hectares to be irrigated • Associated risk in balancing demand and availability• Issue 2: Bringing water to the field(s) • Continuously, rotation, fixed turns, days, hours, what flow is available for farmers?• Issue 3: Grouping farmers or not - units• Issue 4: Who decides? • Water delivery • Demand-based, request-based, supply-based? • Upstream or downstream control?• Issue 5: Water control structures • Discharge control, measurement, fixed or adjustable, sensitivity? December 14, 2011 21
  69. 69. Dimensioning your irrigation system• Take a typical stretch of your system• Determine required water levels along this stretch, taking into account requirements from smaller canals, structures etcetera• Determine available energy gradient per section• Design canals and structures (steady flow)• Check, check and check! What happens when Q is lower, or higher, or whatever (steady flow).December 14, 2011 22
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