This is the sixth lecture of the course 'Irrigation based Agro-ecosystems' conducted at the Faculty of Social Sciences and Humanities of the Rajarata University of Sri Lanka

1. WRMG 2212
Theory 40 hrs
Rajarata University of Sri Lanka
P.B. Dharmasena
0777-613234, 0717-613234
dharmasenapb@ymail.com, dharmasenapb@gmail.com
https://independent.academia.edu/PunchiBandageDharmasena
https://www.researchgate.net/profile/Punchi_Bandage_Dharmasena/contributions
http://www.slideshare.net/DharmasenaPb

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N
C P

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– (Productivity) (Stability)
(Sustainability) (Equity)
(Independence)
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8. .ppt (8)

11. • ET =
• R =
• I =
• D =
• RO =
• S =
• U =
S =(I + R + U) - (D + RO + ET)

15. 
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16. 585 mcm
435 mcm
350 mcm
25 mcm

17. %
2,616 4,794 1,608 34.0
2,772 4,424 587 13.0
3,246 4,592 568 12.0
1,520 2,269 300 19.0
2,278 8,692 5,474 62.0
2,688 10,122 7,862 77.0
2,442 9,843 2,165 22.0
10,327 26,804 11,016 41.0

18. • (field water balance)
• (tank water balance)
• (catchment water
balance)
• (river basin water
balance)
• (soil water balance)
• (environment water balance)

20. 505 MCM
100 MCM
605 MCM
184
MCM
101
MCM
256
MCM
6
MCM
250
MCM
64
MCM
314 MCM

21. 21
P
S

22. ;
2
15-25 25-40 15-25 35-40 10-15
15-25
40-65
55-85
100-145
90-130
1
2
3
4

23. WHC
PPTi ETi
SWi = SWi-1 + PPTi - ETi
Drainage
ET0 . Kc = WR (
Water Requirement)
ET < WR
SWi
Kc =

24. (tank water balance)
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100
20
70
10
6
10 4
4

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37. •
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– D
– D A
– D V) = 0.4 x AD
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– 0.4 x 60 x 05 =

38. •
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– =
– =
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– = x /
– =
– =
– =
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DL b
•
– = /2.
– =
•