The Lower Usutu Smallholder Irrigation Project

The objective of the project is poverty alleviation allowing the people on Swazi Nation land to shift from risky rainfed agriculture to high value crops, as in the NIP, National Indicative Programme, which allocates 70% of development funds to agriculture and rural development.

The project will provide two stage development of small holder irrigation on 11,500ha, served by diverting part of the peak flows of the Usuthu River. The main hydraulic structures are a weir at Bulungapoort to abstract water into a 23km feeder canal leading to a seasonal storage reservoir on the west side of the Bovane ridge, impounded by two 46m high dams and a 7.5m saddle dam.

Two main canals serve the irrigation blocks, north for 5.7km commanding 2,000ha (including 1,300ha by 30m lift pumping) and south for 24km supplying 4,500ha in the Bovane block plus 51km to serve the second stage development of 5,000ha in the Matata block. The total cost of Stage I development was estimated at January 1998 prices to be Eu103mn, of which 75% would be local costs.

The prefeasibility study considered three options:

1. main stream storage at Bulungapoort
2. gravity diversion by weir at Bulungapoort with off stream storage at Bovane
3. pumping from Siphofaneni, near the weir site, and from Usuthpoort, downstream of Big Bend near the Mozambique/South African border.

Option (ii) was chosen and taken as the starting point of the feasibility study.

Three options were then considered:

1. 11,500ha as a single project,
2. only the Bovane block,
3. two stage development of the Bovane and Matata blocks.

The last was recommended, with a first stage implementation period of six years starting in 2000, including headworks for both stages, to be followed immediately by the second stage over four years. One preparatory year, 1999, was allowed for fund raising.

The NIP plans to integrate small holder farming into the commercial market, particularly to diversify and improve productivity, rural incomes and nutrition standards, as well as to increase agricultural exports. It aims for grass roots development, especially the integration of women into the rural economy.

The project area is semi-arid, over-grazed bushland, with some rainfed cotton. Small holders irrigating sugar cane by pumping from the Usuthu already get yields comparable with the commercial plantations and with the project many others will have the same opportunity.

The level of the diversion weir at Bulungapoort, 252.5masl, is restricted by the railway at Holomi station. The intake structure will be combined with the weir using a Tyrol offtake for sediment control. A three bay sand trap will be set in the feeder canal 1.5km down from the weir to flush coarse sand back to the river.

The feeder canal to the river will be concrete lined to minimise losses. The Bovane ridge is a massive dolerite sheet cut by the Mhlathuzane and Golome gorges.

The Mhlathuzane dam will be roller compacted concrete, RCC, incorporating the main spillway, two irrigation outlets, supplying the main canals at 205.0 masl from the lowest drawdown level of 207.0 masl. A bottom outlet is centred at 183.9masl, slightly below the present river bed level. The crest length is 293m, of which 42m is taken by the reinforced concrete overflow spillway, set at the 224.0masl FSL, full supply level, designed to take the 100yr flood.

The Golome dam will be clay core rockfill with no outlets. Its crest length will be 608m at 228.5masl. The high flood spillway, capable of passing a PMF, probable maximum flood, at 228.0masl will be situated between the Mhlathuzane and Golome dams, discharging to the Mhlathuzane river. Its crest of 260m is a broad crested weir at 224.5masl topped by a fuse plug which will breach at the 100yr flood level 225.8masl.

The main canals will be concrete lined, 150mm placed in earth sections, 60mm shotcrete on rock. The Main Canal North crosses the feeder canal twice after the 30m lift pump station and costs may be saved by pumping directly into the MCN from the feeder, when it is operating. Although the Bovane reach of MCS is 24km, the full length of 75 km will be designed in the first stage. Secondary canals will be taken down ridges below the main canals and run along contours when pumped above the main canals. Balancing reservoirs will be used for night and weekend storage for furrow irrigation, but small holders generally prefer dragline sprinklers. The Swaziland Electricity Board may pay for some power lines. Excavation depth is limited to 0.5 - 1.0m and lining soil must be hauled from a distance. Canals will be limited to land of less than 2% slope, with pipes at greater slopes. The Bovane area has land slopes greater than 5%.

There is a thriving sugar industry and a cotton ginnery, both ready to expand. Input suppliers and transport exist in the project vicinity. Small holders get comparable sugar yields to the estates, which should be replicated on the project with more crops. Crop choice will be free depending on agro-climatic conditions, soil suitability and farmer experience, but the study recommends sugar, cotton, dry beans, seed maize, green beans plus others.

Swazi income averages E4,800/yr, but in the project area it is only E500/yr. The FAO poverty line is E1,290/yr. With a base model of 6,000ha and the most likely sugar price, the project EIRR is 6.3%, with a range from 4.7% to 7.2% for extreme sugar prices. Farm income will increase from E2,000/yr to E16,000/yr on 3.5ha. The direct beneficiaries will be 3,400 farm households or some 30,000 people and 5,600 jobs will be created. During the eight years of implementation there will be 5,300 man years of employment in construction. Nutrition will improve. At full development exports of E140mn/yr offset by imports of E68mn/yr will cover 20% of the current deficit of E343mn/yr.

The components of project cost are: upstream works Eu48mn; downstream works Eu18mn; land development, field irrigation Eu13mn; agro-processing Eu8mn; project management 14mn; resettlement Eu2mn; total Eu103mn. Foreign exchange will be 25% and local costs, including Rand, 75%. It is proposed to divide the work into several construction lots. The timing proposed is Yr0 for the finance package, survey and geotechnical work in Yr1, final design and tender documents in Yrs 1/2, tendering and award Yrs 2/3, upstream construction Yrs3/5, downstream construction and land development Yrs4/6, first water MCN Yr 5, MCS Yrs6/7, start Stage II in Yr 7.

For sustainability the project needs professional management and an organisation to co-operate with traditional authority. Central Government and MOAC do not have a strong presence and lack experience of large project implementation. In any case Government is committed to downsizing. Therefore set up a contract Project Management Unit which will leave behind an institution to manage irrigation after implementation. Farmers will own and manage the system which must be self financing through the Lower Usuthu Irrigation Management Association, LUIMA, with a voting majority by elections from water user groups. There will also be Government and agro-processor representatives. LUIMA will be financed by monthly metered water charges.

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This page was last updated on 15 November 2001