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Analysis of your system: what couldyou do…ICID/HistoryDecember 14, 2011                                                   ...
Pampa deChaparrí, Peru                 2
Pampa de Chaparrí,Peru                     • Arid Peruvian north                       coast                     • Pre-Col...
Irrigated areas                  • Three areas irrigated                    from Río Chancay                  • One area f...
million m3                     0                         500                               1000                           ...
Irrigation: when did it go wrong?                             Rio Chancay in year with shortage                           ...
Irrigation: how often did it go wrong?                                              70% cultivation                       ...
(Hayashida 2006)What about the canal system?                                         8
http://delftsoftware.wldelft.nl/index.php?option=cSimplified to this:   om_content&task=view&id=110                       ...
Three scenarios A - Reference:               Racarumi I          Racarumi Ia          Racarumi Ib          Racarumi Ic - I...
Reference layout and fluctuations                   14                   12                   10                   8      ...
Fluctuations with weirs                                                 Low discharge, but                      1.7       ...
Fit with reality?A 900 hectares area in theupstream area shows ahighly regular canalsystem.In the middle area canalsand fi...
Renault et al                 15FAO - MASSCOTE
Procedure to describe and analyse                                    16
17
18
19
Bring back to this for the modeling                                      20
21
The SOBEK scheme                   22
Detail in the schematization           Off-take                Gate 1Incoming    Gate 2           Ongoingcanal            ...
Step 1 for your own design  Try to bring your  system back to  something similar  to the image to the  right: select the  ...
Step 2   Develop a model in Sobek.         Please note that all values to be put in Sobek         need to be known beforeh...
Step 3Run the scenario of a ‘typical day’ in the system.Does the system function as planned on such a ‘typical day’?Try to...
Improving and testing your system• 1) Technicalities• Can all the fields/tertiary units be irrigated?• Is there a canal?• ...
What happens if?• 3) What happens if…• All or some tertiary units do not irrigate?• All or some tertiary units want to irr...
Storage in the system??• Could increase operational flexibility• Could decrease dependence on the canal system• On what le...
Boils down to hydraulic design of the(main) system • Hydraulic flexibility • How does the system behave and respond? • Ope...
For now: let’s move to room 1.97• Do the Sobek tutorial, if you have not done already• Check the two example Sobek schemes...
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CT4410: Modelling of irrigation systems I

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Transcript of "CT4410: Modelling of irrigation systems I"

  1. 1. Analysis of your system: what couldyou do…ICID/HistoryDecember 14, 2011 1Water Resources / Civil Engineering and Geosciences
  2. 2. Pampa deChaparrí, Peru 2
  3. 3. Pampa de Chaparrí,Peru • Arid Peruvian north coast • Pre-Colombian civilizations • Sicán, Chimú and Inca • Between 900 AD and 1532 AD • Abandoned in the 16th century 3
  4. 4. Irrigated areas • Three areas irrigated from Río Chancay • One area from Río La Leche • Río Chancay diverts to Río La Leche River • Chaparrí derived about Canal 1/3 of the discharge 4
  5. 5. million m3 0 500 1000 1500 2000 2500 3000 3500 1914/15 1916/17 1918/19 1920/21 1922/23 1924/25 1926/27 1928/29 1930/31 1932/33 1934/35 1936/37 Year 1938/39 1940/41 1942/43 1944/45 1946/47 Discharges of Río Chancay 1948/49 1950/51 1952/53 1954/55 1956/57 1958/595
  6. 6. Irrigation: when did it go wrong? Rio Chancay in year with shortage (low flow from May) • Lower discharges 120.00 100.00 • Start of higher 80.00 discharges too lateQ (m 3/s) 60.00 40.00 • But also 20.00 • End of higher 0.00 8 9 10 11 12 1 2 3 4 5 6 7 discharges too Month early (in graph) 6
  7. 7. Irrigation: how often did it go wrong? 70% cultivation Water shortages: 0.5 0.45 • 70% cultivated:R iver w ater used (fraction) 0.4 • 6 out of 45 years (less 0.35 0.3 severe) 0.25 0.2 • 80% cultivated: 0.15 • 8 out of 45 years (1 to 3 0.1 months) 0.05 0 • 100% cultivated: 19 /1 5 19 /1 7 19 /1 9 19 /2 1 19 /2 3 19 /2 5 19 /2 7 19 /2 9 19 /3 1 19 /3 3 19 /3 5 19 /3 7 19 /3 9 19 /4 1 19 /4 3 19 /4 5 19 /4 7 19 /4 9 19 /5 1 19 /5 3 19 /5 5 19 /5 7 9 /5 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 19 Season • 11 out of 45 years May June July (severe) 7
  8. 8. (Hayashida 2006)What about the canal system? 8
  9. 9. http://delftsoftware.wldelft.nl/index.php?option=cSimplified to this: om_content&task=view&id=110 9
  10. 10. Three scenarios A - Reference: Racarumi I Racarumi Ia Racarumi Ib Racarumi Ic - Inflow gradual Inflow - Inflow variable IIa Racarumi IIb Racarumi IIc Racarumi Racarumi I Racarumi Ia Racarumi Ib Racarumi Ic B - Main system: - Both inflows Inflow weir Racarumi IIa Racarumi IIb Racarumi IIc Racarumi I Racarumi Ia Racarumi Ib Racarumi Ic C - Proportional: Inflow - Both inflows weirs Racarumi IIa Racarumi IIb Racarumi IIc 10
  11. 11. Reference layout and fluctuations 14 12 10 8 6Discharge (m3/s) 4 2 0 0 24 48 11 72 Hours RI RIIa RIIc
  12. 12. Fluctuations with weirs Low discharge, but 1.7 highly variable 1.6 1.5 1.4 Relative discharge 1.3 1.2 1.1 1.0 0 24 48 72 12 Hours prop RIIa RIIa main RIIc prop RIIc main
  13. 13. Fit with reality?A 900 hectares area in theupstream area shows ahighly regular canalsystem.In the middle area canalsand fields are morevariable in shape, althoughstill fairly regular. (Hayashida 2006)The area downstreamappears as a patchwork ofvaried plots and canals. 13
  14. 14. Renault et al 15FAO - MASSCOTE
  15. 15. Procedure to describe and analyse 16
  16. 16. 17
  17. 17. 18
  18. 18. 19
  19. 19. Bring back to this for the modeling 20
  20. 20. 21
  21. 21. The SOBEK scheme 22
  22. 22. Detail in the schematization Off-take Gate 1Incoming Gate 2 Ongoingcanal canal Gate 3 23 Emergency spill
  23. 23. Step 1 for your own design Try to bring your system back to something similar to the image to the right: select the main features of your system, take a representative stretch/part 24
  24. 24. Step 2 Develop a model in Sobek. Please note that all values to be put in Sobek need to be known beforehand. See the hints and tips on Blackboard. 25
  25. 25. Step 3Run the scenario of a ‘typical day’ in the system.Does the system function as planned on such a ‘typical day’?Try to predict how your system would respond to several “whathappens if…” scenarios. 26
  26. 26. Improving and testing your system• 1) Technicalities• Can all the fields/tertiary units be irrigated?• Is there a canal?• Is the energy head available sufficient?• Can all the fields/tertiary units be drained?• Are the calculations applicable and correct?• …• 2) Functionality of the system• Is it clear how the system has to function?• Are the solutions selected suitable for the functions to be realized?• How does a ‘typical day’ in the system look like?• Does the system function on such a ‘typical day’?• … 27
  27. 27. What happens if?• 3) What happens if…• All or some tertiary units do not irrigate?• All or some tertiary units want to irrigate at the same time?• Other crops are grown?• Structures are damaged or reset?• The maximum rainfall event and no irrigation coincide?• There is no rainfall?• …• 4) Emergency scenarios: how vulnerable is the system?• Upstream users decide to take all the water?• Farmers outside the area want to irrigate?• A very dry year: minimum flows in the river are just half of mean minimum flow?• … 28
  28. 28. Storage in the system??• Could increase operational flexibility• Could decrease dependence on the canal system• On what level?• Within the farm?• Within tertiary unit?• Within the secondary unit?• In reservoirs?• Or in canals? 29
  29. 29. Boils down to hydraulic design of the(main) system • Hydraulic flexibility • How does the system behave and respond? • Operational flexibility • How easy is it to change operation and flows? • Reaction time of the system • How quickly does the system transport the flows according to the new setting? • Unsteady flow conditions may govern your system!!!! 30
  30. 30. For now: let’s move to room 1.97• Do the Sobek tutorial, if you have not done already• Check the two example Sobek schemes on Blackboard • Play with them, change them, understand them• I have an example scheme available for you to build into Sobek• Goal: learn Sobek en learn what information your own design should contain in order to model it properly 31
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