1. ECONOMIC COST AND BENEFITS
1.4
ECONOMIC COST AND BENEFITS

2. Spate irrigated areas are often among the poorest areas
in a country and therefore require special attention

3. There are several ways to support spate irrigation development
Provide earthmoving equipment
Investments:
Improvement of traditional systems
Modern civil engineering

4. All these approaches have different costs, benefits, risks and side-effects

5. Earth moving equipment programs
Making bulldozers available on subsidy/ for free
allows construction of bunds and gully plugs has made it possible
to control flood water where previously this was not possible
Often combined
with gabion structures

6. Earth moving equipment programs
Costs/ benefits:
Low cost (5-125 USD/ ha)
Very large impact
High flexibility
In many areas the ‘only option’
Construction can be ‘farmer-driven’
Recommendation:
In bulldozer programs the
allocation of bulldozer services
should be fair and preferably to
communities rather than individuals
Risks:
distortion of water distribution
creates dependency of farmers
bulldozer bunds less compact, breaks easily

7. If possible, promote local rental market in earthmoving equipment
Sana’a, Yemen

8. Investment: improvement in traditional systems
Example
Fixating diversion of
traditional
flood channel
No change to system of intakes and flood channels
Improve traditional structures with gabions and small civil works
Range of improvements such as bed level fixation, reinforcing diversions,
flow regulation, improved water distribution, improved overflow structures

9. Investment: improvement in traditional systems
Risks:
Maintenance (of gabions) can be problematic
-Not many engineers easily ‘know’ what to do – requires good understanding and interaction
Costs/ benefits:
Medium cost (USD /ha)
Medium impact
No disruption of water rules
O&M burden of farmers drastically reduced
Farmers remain in charge

10. Investment: modernizing spate systems
Typically:
Combined diversion structure, single off-take, extended channel, sedimentation excluder, syphons and sometimes ‘breaching bund’
Example: Wadi Laba, Eritrea
In Pakistan the equivalent civil engineering
approach has used designs that in almost all cases were inappropriate to spate irrigation – leading to spectacular failures such as Mithawan Dam silting up in first year

11. Investment: modernizing spate systems
Costs/ benefits/risks:
High cost (USD /ha)
Difficult to control sedimentation
Operation problematic (gates, cleaning of sedimentation ponds etc..)
Disturbance of water rules – upstream ‘takes charge’
Farmers expect government to maintain

12. Typical investment costs
Type
Cost range (USD/ha)
Examples
Soil bunds with gabion structures
5-125
Eritrea, Pakistan
Flood water spreading
200
Iran
Small systems, permanent headworks
Eritrea, Yemen, Pakistan, Ethiopia
Large systems, permanent headworks
Yemen, Eritrea, Pakistan, Tunisia
Rehabilitation
90-300
Yemen, Tunisia

13. Investment strategy
They can be increased though
through better agronomy,
soil moisture management and
farmer organization – yet even then
Investments per ha in spate irrigation should be modest, because economic benefits in spate irrigation are limited:
Fluctuations in cropped area and production over the years
Risk of total crop failure
Predominance of traditional crops
Diversion and conveyance efficiency in traditional systems already high

14. There are other important advantages of low cost approaches:
Simple technology
Technically often most suitable:
Control of sedimentation
In tune with existing water rules
Independence from external input
Construction by farmers
Low-cost repairs
No ‘total’ failures
Civil engineering approaches only possible in limited number of areas

15. General lessons: High investment returns for:
Improvement of traditional systems
Investments in soil bunds
Subsidized bulldozer programmes
Permanent head works on small systems
Besides, these programmes:
Improve local groundwater water storage
Support improving soil moisture conservation

16. Additional ‘economic’ considerations
Balance investments costs and O&M costs
Advantage of small systems over large systems
Use different time horizons in assessing costs and benefits
Other considerations: livelihood and environment

17. Important to balance initial investment costs as well as subsequent O&M costs

18. Balancing investment and subsequent maintenance costs
Example: Use of Gabions
Especially if inferior quality gabions are used,
maintenance may become difficult and expensive
Balancing investment and subsequent maintenance costs

19. Balancing investment and subsequent maintenance costs
In Wadi Beihan farmers preferred to go back
to the traditional ‘algama’ structures
instead of using gabions
Balancing investment and subsequent maintenance costs

20. Investment in large spate systems often higher per ha than investments in small systems
Because of their complexity (long weirs withstanding
peak floods, sediment excluders, long conveyance
channels) investments in large sized spate systems are
often higher than improvements in small system)

21. Shorter time horizons: Case of Sonwah Dam

22. Shorter time horizons: Case of Sonwah Dam
At the request of farmers a huge earthen bund was built across the tail of the large Nari River in Balochistan.
Inevitably this would cause the river to silt up and force the river to divert itself to a different course. Farmers were aware of this and estimated it would take seven years for this to happen.
They were not worried and argued that:
before the new bund they could not control the flood water from the deep river
if the river would take a new course, for instance one of the flood channels, they would start making diversion bunds in this new course

23. Shorter time horizons: Case of Sonwah Dam
Lessons:
Take a dynamic approach – the river may change its course
This is not a disaster – one can ‘play’ with this and follow the river
But conventional economic analyses based on permanent solutions with twenty year horizons of costs and benefits are not suitable

24. The Final Most Important Consideration

25. Important consideration
Farmers and livestock keepers in spate irrigated area often have no other viable alternative means of support
Often there is no other comparable source of drinking water or fuel wood in the area
Once an area looses it spate system, it is depopulated and the resources and social organization are lost

26. Important consideration
Investment in spate irrigated areas is very much justified from economic and social benefit viewpoint
Best to look at spate irrigation as form of macro catchment water harvesting and not compare it with conventional irrigation
Need to build up the national capacity to support spate irrigation areas in appropriate manner