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Irrigation and drainage
Evolution of irrigation development
Irrigated crop production has been practised since soon after the arrival of the first European settlers, mainly on a small scale. The Noordoewer Scheme on the Orange River was established during the 1930s. The main State investment in irrigation was in the Hardap Scheme that became operational in the late 1960s. The Isisi Scheme on the Zambezi started in the 1980s, while the Etunda Project on the Kunene became operational in 1995/96.
In 2002, 7 573 ha were equipped for irrigation (Table 4). The main irrigated areas are:
- The Hardap Scheme, supplied from the Hardap Dam. Equipped area is about 2 260 ha;
- Schemes along the Orange River (such as Noordoewer Scheme, Aussenkehr Scheme). Equipped area is about 2 000 ha;
- Schemes along the Okavango River (such as Shadikongoro Scheme) with about 1 350 ha equipped area, of which about 600 ha are upstream of the confluence with the Cuito River, and about 750 ha are downstream of the junction;
- The Etunda Scheme on the Kunene River with about 640 ha equipped area;
- Schemes on the Zambezi River, like the Katima Farm (approximately 200 ha) and the Isisi Scheme (36 ha, currently not operational).
In addition to that, flood recession cropping (mainly maize) is practised in the flood plains of the Okavango and Zambezi rivers; in 1992, this activity covered 2 000 ha.
No recent information on areas under different irrigation methods is available. In 1992, 2 950 ha were under surface irrigation (basin and furrow), 1 845 ha were under centre pivot and sprinkler and 1 347 ha under drip or micro-sprinkler. New developments favour the use of sprinkler irrigation technologies and at present the figures are estimated to be 2 950 ha, 3 276 ha and 1 347 ha respectively (Table 4 and Figure 2). Irrigation methods practised in some of the major schemes are:
- Hardap Scheme: mainly surface and sprinkler, some farmers are changing to drip;
- Noordoewer Scheme: mainly flood irrigation;
- Etunda Scheme: surface irrigation (day) and center pivot irrigation (night);
- Shadikongoro Scheme: centre pivot;
- Isisi Scheme: flood irrigation (paddy rice).
The majority of the irrigation schemes use surface water. About 78 percent are estimated to be irrigated from surface water, the remaining from groundwater (Figure 3). It is estimated that irrigation water is pumped to 79 percent of the equipped areas.
There are four basic categories of farming in the irrigation sub-sector:
- Smallholders, generally on 1 ha plots, receive substantial government support, with free extension support, water and inputs, including land preparation;
- Medium-scale commercial farmers have been settled on 30 ha blocks and are able to obtain safe loans from the government through the Land Bank;
- Large-scale commercial farms are the major participants in the sub-sector and consist of private landowners who have undertaken irrigation on their own account, albeit often with support from the government;
- Parastatal or state farming, carried out by the National Development Corporation (NDC). These farms are commercially operated as State Farms, with management and paid labour. Several schemes under the NDC have been settled by farmers on 3 to 4 ha plots. The NDC manages and provides inputs to farmers as credits under soft loans. Any new government development is normally executed by the NDC.
Role of irrigation in agricultural production, the economy and society
No recent information on irrigated crops is available. In 1991, the major irrigated crops were maize, alfalfa and pasture, wheat and cotton (Table 4). Irrigated land areas may be characterized by low-value crops such as wheat, maize and alfalfa, and high-value crops including grapes, dates, cotton and melons. The bulk of irrigated areas is under low-value crops. Currently irrigation development is taking place along the Orange River for the production of table grapes for the European and USA markets.
No nationwide study of the costs and benefits of irrigation is available. However, for example, the water supply in Hardap is heavily subsidized, rather than being charged for at an economic rate, or the irrigation projects are not economically viable.
One constraint to some of the areas with large irrigation potential is that markets are far away:
- In the case of the Orange River area, Windhoek and Capetown are both about 800 km away, although the area lies adjacent to the main Namibia-South Africa road;
- In the case of the Zambezi area, Windhoek or Walvis Bay are about 1 300 km away;
- The Kunene basin is a remote and isolated area.
No monitoring system for water used per crop is in place, and the efficiency with which water is used in irrigation is generally not measured. Thus, farmers are not encouraged to invest in high-value crops, which Namibia imports heavily. Water used in subsistence agriculture seems to be more productive than in the commercial sector.
Status and evolution of drainage systems
It is estimated that in 2003, about 2 000 ha were drained with subsurface drains. It is known that there are problems with the drainage system in the Hardap scheme, where the subsurface system has become blocked and the surface drainage canals and riverbed have become infested with reeds (Phragmites australis), which block the flow during floods, causing a severe problem.