|Pays, régions, bassins fluviaux|
|Ressources en eau|
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|Irrigation et drainage|
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|ODD Cible 6.4|
|Year: 2005||Revision date: --||Revision type: --|
|Regional report:||Water Report 29, 2005|
Namibia lies along the southwestern coast of Africa, and is bordered by Angola in the north, Zambia and Zimbabwe in the northeast, Botswana to the east, South Africa in the south, and the Atlantic Ocean to the west. It occupies an area of 824 290 km2. Its north-south extent is about 1 300 km, while it measures between about 450 and 900 km from east to west, excluding the Caprivi Strip panhandle in the northeast. The highest point is the Konigstein with an altitude of 2 606 m.
The country is divided into three topographical regions:
The three main vegetation regions are:
The cultivable area is estimated to be 25 million ha. In 2002, the cultivated area was 820 000 ha, of which 816 000 ha arable land, while 4 000 ha were under permanent crops, accounting together for about 1 percent of the total land area of the country and 3 percent of the cultivable area (Table 1).
Namibia’s climate is characterized by hot and dry conditions and sparse and erratic rainfall. Within Africa the climate is second in aridity only to the Sahara Desert and 92 percent of the land area is defined as hyper-arid, arid or semi-arid. Rainfall patterns are characterized by their high temporal and spatial variability. Conventional statistical descriptors such as mean and even median are often difficult to use and estimates of rainfall characteristics and patterns based on point measurements are problematic.
Mean annual rainfall is estimated to be 285 mm. Of the total rainfall, 83 percent evaporates, 14 percent is used up by vegetation, 1 percent recharges groundwater and only 2 percent becomes runoff and may be harnessed in surface storage facilities. Net evaporation can be as high as 3 700 mm per year. In the coastal plateau the average monthly evapotranspiration always exceeds the rainfall by a factor of up to five. The coastal region is an arid desert less than 300 m above sea level. Along the coastal belt, precipitation from advective fog exceeds precipitation from rainfall.
Mean annual temperatures are below 16 °C along the southern coast, between 20 °C and 22 °C in large parts of the country’s interior and the eastern parts, and above 22 °C in the north. Temperatures are moderated by the cold Benguela currents along the coast. In Windhoek average temperature ranges are from 6 °C to 20 °C in July to 17 °C to 29 °C in January.
The country’s population is about 2 million (2004), with an annual growth rate of 2.1 percent (Table 1). Of the total population, 67 percent are rural. Namibia is one of the world’s most sparsely populated countries with a population density of 2.4 inhabitants/km2. Wealth distribution is highly inequitable, and there is a high incidence of extreme poverty. In 1998, 10 percent of the population received 65 percent of income leaving only 35 percent for the remaining 90 percent. Subsistence farmers and livestock herders, who earn their livelihoods in extremely harsh and stressful conditions account for 70 percent of the population. The unemployment rate is 40 percent. In 2002, 98 percent of the urban and 72 percent of the rural population were using improved drinking water sources; coverage is 80 percent at the national level (Table 1).
Namibia’s GDP was US$4 700 million in 2003. The value added by agriculture was 10 percent of GDP, of which 75-80 percent are attributed to livestock farming. The sector provides occupation for 38 percent of the economically active population and 58 percent of the population working in agriculture is male.
Agriculture is segmented in two very different sectors:
Growth in the agricultural sector has averaged 1.2 percent per year since independence in 1988, while since 1993 growth has averaged 2.8 percent per year. The sector is strongly influenced by climatic conditions and as a result the contribution to GDP has varied between 6.8 percent and 12.3 percent since 1990, with low contributions in drought years. Since 1995, agricultural growth has barely kept pace with population growth, which can be attributed directly to the below-average rainfall in Namibia over the past few years. As a result of low rainfall there was considerable de-stocking of livestock in 1996, which led to a 60 percent drop in the number of cattle marketed in 1997. Cereal production has been similarly affected. Growth in the agricultural sector is expected to be weak in the coming years, implying negative per capita growth. Food imports amount to about 7 percent of the total value imports. Namibia imports sugar, maize, edible offal, wheat, concentrated milk and cream, cheese and butter. Agricultural exports comprise mainly livestock and meat products and account for about 15 percent of all Namibian exports.
The value added per m3 of water in irrigation is very low compared to manufacturing and service sectors, about US$1.20/m3 compared to U$44/m3 and US$93/m3 respectively.
The main river basins in Namibia are:
The percentage of mean annual precipitation that ends up as river flow in ephemeral systems in Namibia varies from as little as below 1 percent up to around 12.5 percent for parts of the Fish River basin. The remainder goes to direct evaporation and evapotranspiration, with the latter being by far the greatest component. Some of the runoff recharges alluvial aquifers on its way downstream, and in so doing the majority of ephemeral river floods ultimately disappear entirely into the sand. Namibia’s ephemeral rivers are ‘effluent’ systems. This means that the river feeds the groundwater table, rather than having its flow sustained by a high groundwater table, as is the case with ‘influent’ rivers.
Namibia’s groundwater occurs in a wide range of rock types making groundwater management a complex process. It provides a buffer against drought in many regions of the country, but it does remain inherently vulnerable to overabstraction and pollution. Aquifers occurring in Namibia are classified as alluvial, Kalahari, fracture, Karst or artesian aquifers. Parts of the Grootfontein-Otavi-Tsumeb Karstland aquifer have been subject to thorough investigations and modelling, and for the Otavi Mountain Area the following recharge conditions were identified:
Although the ephemeral rivers of Namibia have dry sandy or rocky river beds for most of the year, they are conduits for subsurface flow and contain a number of wetlands defined as ‘shallow, swampy or marshy areas with little or no water flow’ or ‘waterlogged solid dominated by emergent vegetation’. In Namibia this description applies to most sections of all westward flowing rivers north of the Kuiseb River. Wetlands are periodically used for hunting and seasonal fishing. Currently, their utilization includes communal domestic stock farming, small mining enterprises and small-scale gardening. The ecology of Namibia’s wetlands is very fragile. Over-exploitation of alluvial aquifers and the building of dams, especially on the Kunene River and the Orange River, which reduce the flow downstream are potential threats to those wetlands that depend on them. The protection and conservation of wetlands is therefore an important priority and the government of the Republic of Namibia has initiated several efforts towards ensuring this. Wetlands of international importance in Namibia, and Ramsar sites, are the Etosha Pan, the Orange River Mouth, Sandwich Harbour and Walvis Bay.
Total natural renewable water resources of Namibia are estimated at 45.46 km3/yr, of which only 6.16 km3/yr are internally produced (Table 2). Over half of the external water resources comes from the Zambezi River, while smaller amounts are contributed by the Orange, Kunene and Kwando rivers and rivers from the Okavango. From the total accounted natural flow of the border rivers Zambezi, Kunene and Orange of 28 km3/yr, only 0.255 km3/yr is under agreement (0.07 from the Orange River and 0.185 from the Kunene River) and should thus be considered as actual flow. This reduces the natural renewable water resources of 45.46 km3/yr to actual renewable water resources of 17.715 km3/yr.
A number of ephemeral rivers have been tapped by building dams. The total storage capacity of the major dams is about 0.71 km3 and their 95 percent assured combined yield is 95.83 million m3/yr. In addition to these larger reservoirs, there are thousands of small farm dams scattered around the ephemeral river basins.
The total assured safe yield of Namibia’s water resources is 660 million m3/yr, distributed as follows: groundwater 300 million m3/yr, ephemeral rivers 200 million m3/yr, perennial rivers 150 million m3/yr and unconventional sources 10 million m3/yr.
Treated wastewater is used more and more often for applications that do not require drinking water quality, such as landscape irrigation. It was found that the return flow in Windhoek and urban centers equals 40 percent of freshwater consumption and can be reused after treatment. Reuse of water is practised in Namibia in many urban areas such as Swakopmund, Walvis Bay, Tsumeb, Otjiwarongo, Okahandja, Mariental, Oranjemund and Windhoek. In Windhoek, 1.14 million m3 of treated effluent were used for irrigation in 1997 and reclamation of water for potable reuse has been practised since 1968. The plant could supply 8 000 m3/day, which was about 19 percent of the average daily water demand of the city in 1997. A new reclamation plant with an increased capacity of 21 000 m3/day was completed in 2002, and the old plant will in future be used for reclaiming irrigation water. Wastewater recycling is practised by a number of mines. It is estimated that in the future 7 million m3/yr from Windhoek and 10 million m3/yr from other centres could potentially become available.
Recently a contract for the design and construction of a coastal desalination project was tendered.
Namibia shares the following perennial rivers with five riparian states:
A number of ephemeral rivers, such as the Auob and Nossob cross into Botswana and South Africa, but their flows are so irregular that their importance as shared surface water sources is not significant. Groundwater flow in eastern Namibia is generally in an eastern direction, but no attempt has been made to quantify this flow and it has not been raised as an issue of shared resources.
Namibia is highly dependent on its neighbouring countries for securing its water supply, particularly South Africa and Angola due to the large portion of the country’s population living near or along the banks of the rivers shared with these countries. It is estimated that shared rivers currently provide around one third of the water consumed in Namibia. Total abstraction from the shared perennial rivers in 1999 was estimated at almost 100 million m3. To ensure good cooperation with its neighbours, Namibia has developed a regulatory framework, facilitates the establishment of a Basin Management Committees and is reviewing all agreements signed during pre-colonial and post-colonial times. The process of setting up a structure for dealing with shared water issues is in an advanced stage.
Some of the existing agreements and commissions between Namibia and its neighbours as related to internationally shared water resources are:
Namibia has either signed or ratified numerous international protocols and conventions concerning water, notably those designed to protect the environment, including: i) the Zambezi River System Action Plan (ZACPLAN); ii) the UN Convention on the Law of the Non-Navigable Uses of International Watercourses; iii) the International Convention on Wetlands (Ramsar); iv) the SADC Protocol on Shared Watercourses. Another multinational agreement with a bearing on water matters is the Southern African Regional Commission for the Conservation and Utilization of the Soil (SARCCUS) established in 1948 with Angola, Botswana, Lesotho, Malawi, Mozambique, Namibia, South Africa and Swaziland as members. One of its components was the Standing Committee for Hydrology.
Total water consumption in Namibia was 300 million m3 in 2000 (Table 3 and Figure 1). Agriculture was the largest water user accounting for 213 million m3, of which 136 million m3 for irrigation (45 percent of total) and the remaining 77 million m3 for livestock (26 percent). The municipal sector followed with 73 million m3 (24 percent) and industry with 14 million m3 (5 percent).
The highest consumption of irrigation water was in the Fish and Orange River Basins with 41.5 and 41.0 million m3 respectively. In 2000, 30 million m3 of groundwater were used for irrigation, which is 22 percent of the total consumption of irrigation.
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:
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:
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:
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:
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.
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.
A number of institutions are responsible for different aspects of water supply, management and use, including government departments, parastatal institutions (such as municipalities and community-based Water Point Committees), private organizations, and individuals.
Three key institutions involved are:
Government policy is that so-called "irrigation scheme management boards" should be established to take over ownership and responsibility for irrigation scheme infrastructure. Management agreements would be established for each scheme.
A Joint Irrigation Authority between Namibia and South Africa, known as the Noordoewer/Viooldrift Irrigation Board, was established 1993. This board only covers irrigation schemes along the Orange River. In the Etunda scheme, lack of continuity in proper management and discipline is evident, leading to poor performance and maintenance. In the Shadikongoro scheme there was a lack of a clear understanding between project management and the local authority. This led to continuous interference by the local authority and resulted in unrest amongst the workers on more than one occasion. Eventually the farm manager was removed and since then, with proper management in place, the project seems to be coping financially and good yields have been achieved.
Decentralization is a national policy and thus responsibility for rural water supply is being transferred to the regional level through the establishment of Water Point Committees (WPCs) in the communal areas of Namibia. In total 3 673 WPCs are needed. By 1997/98, 1 703 (or 46 percent) of those had been established. It is hoped that by 2007 complete community-based management of the water points will have been achieved.
According to the Water and Sanitation Sector Policy (WASP) of 1993, water supplied for irrigation by the State is to be charged at an economic rate, which may be reduced through a special subsidy. In the Hardap irrigation scheme, for example, NamWater supplies unprocessed water to farmers at a tariff of US$0.005/m3.
Full cost recovery in the water sector represents one of the major challenges for the water sector. Opposition to water pricing is widespread in Namibia and subsidies for water consumption still exist in many sectors, and particularly in the irrigation sector.
According to Article 100 of the Constitution of the Republic of Namibia, "Land, water and natural resources below and above the surface of the land...of Namibia shall belong to the State if they are not otherwise lawfully owned".
The Water Act 54 of 1956 has a colonial origin and applies to Namibia the riparian principles of well-watered European countries. It is not only outdated but also, and above all, inconsistent with the country’s hydrologic reality. It predicates the right to water through ownership of riparian land and thus effectively excludes non-landowners, particularly in the rural areas, from having adequate access to water. The Government of Namibia is currently in the process of drafting the blueprint for a new Water Act for Namibia to replace the Water Act 54 of 1956. The draft of the new legislation includes:
Legislation on irrigation in Namibia has been in draft form since 1993. Two main constraints are impeding progress. On the one hand, the government lacks the capacity to draft legislation which is in line with existing national and neighbouring country legislation. On the other hand, massive investment is needed to upgrade existing irrigation scheme infrastructures to levels that users could be expected to assume responsibility for.
The National Agricultural Policy of 1995 has the following guidelines relating to irrigation:
The Namibia Water Corporation Act 12 of 1997 (also known as NamWater Act) stipulates the objectives of NamWater.
In 1998, the Government of Namibia launched a major review of current water resource management practices, approaches and policies through the Namibia Water Resources Management Review, with the long-term objective of achieving equitable access to, and the sustainable development of, water resources by all sectors of the national population.
The National Water Policy was adopted in 2000 and paved the way for the implementation of integrated water resources management.
A variety of environmental problems are experienced in Namibia’s irrigation schemes. While no figures exist as to the extent of these problems, anecdotal evidence suggests that most are small-scale and manageable. Environmental problems include soil salinity problems in the Hardap and Aussenkehr Schemes, siltation of and reed growth in canals and weed invasion in the Hardap Scheme, soil compaction and runoff problems at the Shadikongoro farm in the Okavango Region.
Apart from the above, good drainage and/or good quality water leave most schemes trouble-free. For example, although the Naute Scheme’s soils are saline, water quality and drainage are good and so leaching effectively deals with salinity. On small-scale groundwater irrigation schemes, it is often found that boreholes with sufficient pressure for irrigation tend to be those with good quality water, and vice versa.
Given the water scarcity of Namibia, it is natural that there is competition for water According to the WASP of 1993, the first priority for water allocation should be accorded to municipal use, while irrigation has second priority together with mining and industry. It was also proposed that irrigation should be regarded as an interim use until the water is used for higher value consumption with higher economic returns.
While most irrigation problems are technically manageable, in terms of dealing with proximate causes (such as excessive use of water and lack of maintenance of drainage systems), it is essential to address the ultimate causes such as low water costs and lack of user responsibility for irrigation scheme infrastructure, so as to encourage farmers to change their management practices.
To ensure a sustainable and economically viable future development of irrigation, the following issues would need to be addressed:
It is estimated that the country’s total water demand will reach about 475 million m3/yr by 2015, against 300 million m3 at present, made up of 93 million m3 for municipal purposes (including industry and tourism), 342 million m3 for agriculture (including irrigation and livestock) and 40 million m3 for mining.
Christelis, G. and Struckmeir, W. (eds). 2001. Groundwater in Namibia: an explanation to the Hydrogeological Map.
The World Conservation Union (IUCN). 2002. Overcoming constraints to the implementation of Water Demand Management (WDM) in southern Africa. Namibia country report. Prepared by Karukirue Tjijenda, Department of Water Affairs, Namibia.
Ministry of Environment and Tourism. 2001. Environmental Assessment Guidelines. Sector: Irrigated Agriculture.
Ministry of Environment and Tourism. 2001. Environmental Assessment Guidelines. Sector: Water Infrastructure. Prepared by: Namibia Resource Consultants cc. Windhoek.
Ministry of Environment and Tourism. 1999. State of Environment Report. Agriculture and land resources and freshwater resources.
Ministry of Agriculture, Water and Rural Development, Department of Water Affairs. 1991. Perspective on Water Affairs.
Ministry of Agriculture, Water and Rural Development, Department of Water Affairs. 1993. Central Area Water Master Plan. Phase I. GTZ.
Ministry of Agriculture, Water and Rural Development. 1994. Identification and prioritization of irrigation development opportunities on the Orange River.
SADCC [Southern African Development Coordination Conference]. 1992. Regional Irrigation Development Strategy, Country Report: Namibia.
UNDP. 1998. Namibia Human Development Report 1998. Prepared by UNDP and UN Country Team.
Van der Merwe, B., et al. 1999. IUCN Water Demand Management Country Report - Namibia.
Windhoek Consulting Engineers (WCE). 2000. Analysis of Present and Future Water Demand in Namibia.
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