ECONOMIC COST AND BENEFITS 1.4 ECONOMIC COST AND BENEFITS

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

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

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

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

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

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

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

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 200-400/ha) Medium impact No disruption of water rules O&M burden of farmers drastically reduced Farmers remain in charge

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

Investment: modernizing spate systems Costs/ benefits/risks: High cost (USD 600-3000/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

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 180-450 Eritrea, Yemen, Pakistan, Ethiopia Large systems, permanent headworks 650-3500 Yemen, Eritrea, Pakistan, Tunisia Rehabilitation 90-300 Yemen, Tunisia

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

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

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

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

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

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

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

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)

Shorter time horizons: Case of Sonwah Dam

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

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

The Final Most Important Consideration

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

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