Drain for Gain: Managing Salinity in Irrigated Lands

Drain for Gain: Managing Salinity in Irrigated Lands

Webinar #8

Henk RitzemaWageningen 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 0.32Salt-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 requirementIrrigation & 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 Irrig

atio

n (m

m)

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

ECe

(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


Drainage sustains and increases yields and rural incomes.

IDNP, 2003

Ali, et al., 2001


Drainage protects irrigation investments

IDNP, 2003


Drainage infrastructure serves rural and urban residents as well as industry

Scheumann, 1997


Drainage protects human lives

IDNP. 2003


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


Drainage and the protection of water quality

El-Guindy, S., 1989

Seven reasons why drainage is neededSUMMARY1. 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.


• 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


Enforcement of rules and regulations is difficult

IDNP, 2003


With small farmers, drainage is always a joint-effort

IDNP, 2003; Ritzema, 2009


Boundaries irrigation unit

≠ drainage unit

Bos, 2006


Disposal of drainage water creates off-site externalities

Roest et al., 2006

250 1 00

0 0

5 00 20 0

7 50 30 0

vo lu m e o f w a te r

in m / ha3

n itra te lo s s

in kg N O / h a3

1 986 1 98 7 198 8

fig u re 2 5 .2

d r a in a g en itra te lo s s


High initial investments versus long-term benefits

Ritzema et al., 2007


Reuse of drainage water

IDNP, 2003

Seven institutional aspects why drainage is different

SUMMARY:1. Drainage is at the end of the pipeline2. Enforcement of rules and regulations is difficult3. With small farmers, drainage is always a joint-

effort Boundaries irrigation unit drainage unit4. Disposal of drainage water creates off-site

externalities5. High investment costs & benefits are long-term6. Reuse of drainage water.


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


Investments in drainage

infrastructure: low or

high

Nijland, et al., 2005


Organisation: Irrigation

and/or Drainage

Departments to be

modified?

IDNP, 2003; Ritzema, 2009


Maintenance of the drainage infrastructure

IDNP, 2003; HW Wallingford


Participatory drainage management

Malano, 2000


Reuse of drainage water

El-Din El-Quosy, D., 1989


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 infrastructure5. Participatory drainage management6. Reuse of drainage water7. Safe disposal


CONCLUSIONS:1. Drainage is needed 2. Drainage pays3. Drainage & irrigation4. Role of Government in financing, regulation and supervision5. Decentralised drainage management6. Stakeholders participation in planning, investment and

management7. 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

Drain for Gain: Managing Salinity over Irrigated Lands

Henk Ritzema

Email: [email protected]

www.TheWaterChannel.tv/SaltyWorld

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Drain for Gain: Managing Salinity in Irrigated Lands

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