Drain for Gain: Managing Salinity in Irrigated Lands Webinar #8 Henk Ritzema Wageningen University,...
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Transcript of Drain for Gain: Managing Salinity in Irrigated Lands Webinar #8 Henk Ritzema Wageningen University,...
Drain for Gain: Managing Salinity in Irrigated Lands
Webinar #8
Henk Ritzema
Wageningen University, Wageningen, The Netherlands
Worldwide agricultural areas with/without irrigation and drainage
Nijland et al., 2005; Ritzema, 2009
Waterlogging and salinity in irrigated agriculture
Indicator Unit World Egypt India Pakistan
Irrigated area (Mha) 272 3.4 57.2 16.7
Drained Area (Mha) 190 3.0 2.5 7.5
of which SSD (Mha) 1.9 0.025 0.32
Salt-affected areas (Mha) 10-16% 1.0 6.7 2.4
of which waterlogged (Mha) 0.6 4.5 1.7
ICID, 2003
Ritzema, 2009
Artificial drained areas
Feick et al, 2005; Ritzema, 2009
Sources of the salts
Irrigation
Capillary Rise
Precipitation
De Ridder and Boonstra, 2006
Irrigated agriculture: source of salts
Salts in irrigation water: 0.2 – 0.8 mg/l = 2.5 – 10 ton/ha/year
Example Egypt
Irrigation:
Vi = 1240 mm/year = 1240 x 10-3 x 104 m3/ha/year = 12.4 x 103 m3/ha/year
Salinity of irrigation water:
ECi = 0.3 dS/m = 0.3 x 640 mg/l = 192 mg/l = 1.92 x 10-4 ton/m3
Total salts brought into the soil:
S = Vi x ECi = 12.4 x 103 m3/ha/year x 1.92 x 10-4 ton/m3 = 2.4 ton/ha/year
Salts are brought in with irrigation water
Ritzema, and Braun, 2006
Leaching requirement
Irrigation & Precipitation ET
watertable
Deep
Percolation
R*
Root zone
Van Hoorn and Van Alphen, 2006
Drainage needed to remove the salts
Irrigation efficiency Leaching requirement
Brouwer et al, 1989
Leaching requirement10 – 40 % depending on ECi and ECe
Ayers and Westcot, 1994
Salinization is a slow process
-100
0
100
200
300
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Irr
iga
tio
n (
mm
)
Scenario I - Summer Scenario II - Winterr E-P
0.0
2.0
4.0
6.0
8.0
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
EC
e (
dS
/m)
ECe - Scenario I - Summer ECe - Scenario II - Winter
Van Hoorn and Van Alphen, 2006
DRAINAGE: The forgotten factor in agricultural water management
Seven reasons why drainage is needed!
Seven institutional aspects why drainage is different.
Seven challenges to make drainage work!
Scheumann, 1997
Seven reasons why drainage is needed (1)
Drainage protects the resource base for food production
Ritzema et al,, 2007
Pearce and Denecke. 2001
Seven reasons why drainage is needed (2)
Drainage sustains and increases yields and rural incomes.
IDNP, 2003
Ali, et al., 2001
Seven reasons why drainage is needed (3)
Drainage protects irrigation investments
IDNP, 2003
Seven reasons why drainage is needed (4)
Drainage infrastructure serves rural and urban residents as well as industry
Scheumann, 1997
Seven reasons why drainage is needed (5)
Drainage protects human lives
IDNP. 2003
Seven reasons why drainage is needed (6)
Drainage services improve health conditions
0 .8
0 .7
0 .6
0 .5
0 .4
0 .3
0 .2
0 .1
0
fra c tio n p o s itive
c o n tro lss ta rt
c o n tro lse n d
c o n tro l m e a s u re sc h e m ic a le n g in e e rin gm e d ic a l
1 9 6 5 1 9 7 0 1 9 7 5 1 9 8 0 1 9 8 5 1 9 9 0 1 9 9 5ye a r
Ritzema and Braun, 2006
Seven reasons why drainage is needed (7)
Drainage and the protection of water quality
El-Guindy, S., 1989
Seven reasons why drainage is needed
SUMMARY
1. Drainage protects the resource base for food production.
2. Drainage sustains and increases yields and rural incomes.
3. Drainage protects irrigation investment.
4. Drainage infrastructure serves rural and urban residents as well as industry.
5. Drainage projects human lives.
6. Drainage services improved health conditions.
7. Drainage and the protection of water quality.
DRAINAGE: The forgotten factor in agricultural water management
• Seven reasons why drainage is needed!
• Seven institutional aspects why drainage is different.
• Seven challenges to make drainage work!
Seven institutional aspects why drainage is different (1)
Drainage is at the end of the pipeline
Madramootoo, 1997, IDNP, 2003
Seven institutional aspects why drainage is different (2)
Enforcement of rules and regulations is difficult
IDNP, 2003
Seven institutional aspects why drainage is different (3)
With small farmers, drainage is always a joint-effort
IDNP, 2003; Ritzema, 2009
Seven institutional aspects why drainage is different (4)
Boundaries irrigation unit
≠
drainage unit
Bos, 2006
Seven institutional aspects why drainage is different (5)
Disposal of drainage water creates off-site externalities
Roest et al., 2006
250 100
0 0
500 200
750 300
vo lum e o f w a te r
in m / ha3
n itra te lo s s
in kg N O / h a3
198 6 198 7 198 8
fig u re 2 5 .2
d r a in a g en itra te lo s s
Seven institutional aspects why drainage is different (6)
High initial investments versus long-term benefits
Ritzema et al., 2007
Seven institutional aspects why drainage is different (7)
Reuse of drainage water
IDNP, 2003
Seven institutional aspects why drainage is different
SUMMARY:
1. Drainage is at the end of the pipeline
2. Enforcement of rules and regulations is difficult
3. With small farmers, drainage is always a joint-effort Boundaries irrigation unit drainage unit
4. Disposal of drainage water creates off-site externalities
5. High investment costs & benefits are long-term
6. Reuse of drainage water.
DRAINAGE: The forgotten factor in agricultural water management
Seven reasons why drainage is needed!
Seven institutional aspects why drainage is different.
Seven challenges to make drainage work!
Seven challenges to make drainage work (1)
Institutional menu for drainage goods and services
Ritzema, et al., 2003
Seven challenges to make drainage work (2)
Investments in drainage
infrastructure:
low
or
high
Nijland, et al., 2005
Seven challenges to make drainage work (3)
Organisation:
Irrigation and/or
Drainage Departments
to be modified?
IDNP, 2003; Ritzema, 2009
Seven challenges to make drainage work (4)
Maintenance of the drainage infrastructure
IDNP, 2003; HW Wallingford
Seven challenges to make drainage work (5)
Participatory drainage management
Malano, 2000
Seven challenges to make drainage work (6)
Reuse of drainage water
El-Din El-Quosy, D., 1989
Seven challenges to make drainage work (7)
Safe disposal
Ritzema and Brain, 2006
Seven challenges to make drainage work
SUMMARY:1. Institutional menu for drainage goods and services
2. Investments in drainage infrastructure: low or high?
3. Organisation: State Irrigation Departments have to be modified?
4. Maintenance of the drainage infrastructure
5. Participatory drainage management
6. Reuse of drainage water
7. Safe disposal
DRAINAGE: The forgotten factor in agricultural water management
CONCLUSIONS:
1. Drainage is needed
2. Drainage pays
3. Drainage & irrigation
4. Role of Government in financing, regulation and supervision
5. Decentralised drainage management
6. Stakeholders participation in planning, investment and management
7. Co-ordination among the organisations should be institutionalised.
The Way Forward
• Balancing top-down against bottom-up
• From standardization to flexibility• Focus on capacity development.
Ritzema, 2009
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