|2.0 THE PRINCIPLE OF APPROPRIATE WATER SYSTEMS
2.1 INTRODUCTORY REMARKS
Many of the parameters discussed in several publications as well as planning and design studies can also be observed in the evaluation of existing water supply and water disposal schemes in Namibia. Very few real 'Namibia-Adopted-Development-Systems'  have so far been developed and implemented. As in the case of transport systems the densely populated regions in Namibia's north and north-east have no adequate water supply or water disposal systems. In these areas lives more than half of the population of the country (U.N.-estimate for the whole of Namibia is ca. 1,5 millions in 1985). Ovamboland alone accounts for over 600.000 persons. According to U.N.-sources and -norms, the vast majority of the rural population, being small farmers with subsistence crops and cattle, lives below the poverty line .
Therefore, this study concentrates on the Namibian problem areas in Ovamboland and the Okavango but also on some impoverished areas in Namibia's south, like, for instance Gibeon. Appropriate technologies will be discussed by means of real case studies which are mainly supported by community development activities undertaken by the Council of Churches in Namibia and its member churches, financed generally by donor agencies abroad and investigated by "Namibia Consult Incorporated" between 1987 and 1989.
Successful implementation of projects requires first of all a correct choice of technology. Not only construction, but especially the subsequent operation and maintenance of facilities, will fail if technology is not appropriate for the circumstances. This slogan is valid for all developing countries with a 'third-world-problematic', also for Namibia. We have not only to do with overdesigned, inappropriate and uneconomical civil engineering systems for mainly the interests of the colonial power like ambitious freeways, huge water supply canal schemes and wastewater disposal plants but also with pour flush toilets which are clogged; latrines used as storage sheds; handpumps failed because they are over-used, sewage treatment plants inoperative due to a lack of spare parts, inadequate or interrupted services due to lacking fuel or disinfectants. All these manifestations can be found at many places in Namibia. They are not indicative of faulty technologies or un-educated people but in most cases the result of improper, un-appropriate designs and technology choices by the civil engineering designer.
If the design choice was wrong the system will ultimately fail because the technology does not reflect the community's so economic and socio-cultural environment. Any design choice must reflect the community's preferences. The designer must, therefore, make this design choice with the community and based on thorough understanding of socio-cultural conditions and adequate knowledge of the community's resources - human, financial, institutional - and the community's willingness to commit them to the project. This knowledge can only be gained by communication with the prospective users and the community's participation in the project's development and later operation and maintenance processes. Special effort must be made to involve women in the consultative process because they are the providers of primary health care to their families and the community as a whole. This includes normally responsibilities for water supply and sanitation. Civil engineers need to treat women as active participants in the project rather than passive recipients of its benefits. The feasibility of making women responsible for operation and maintenance should always be explored because of their obvious motivation to keep the facilities in good repair.
In this regard the mainly South-Africa-educated civil engineers in Namibia have failed in most cases. Communication with the people in order to develop self-help schemes for the communities which follow above basic principles are not in line with the ideas of a colonial administration which also ruled the civil engineering industry in Namibia for so long. This statement can even observed in the establishment of many water supply and waste water disposal systems so far developed in Namibia. They are overdesigned, uneconomical and not functional in many cases . The local communities were not involved in the design, construction, operation and maintenance processes. Many examples exist in this regard.
An important factor which has to be stressed in the implementation of development schemes is the basic issue of the rural areas in terms of effective people's participation in political and social decision-making. Community development must be seen as a process by which the efforts of the people themselves are combined to improve the economic, social and cultural conditions into the life of the nation, and to enable them to contribute fully to national progress. Hence, overall development can be brought about only with effecting participation of the people, backed by the co-ordination of technical and other services, necessary for securing the best of such initiative and self-help. It is a technology that will be geared towards easing tasks of the most vulnerable members of the Namibian society, specifically the rurally based .
It is becoming increasingly apparent that the growing population in Namibia is giving rise to a problem which should become a top priority, namely that of identifying - and as far as possible eliminating - existing and potential health hazards, especially outside the areas of the modern sector of Namibian economy. These obstacles must be overcome if any upgrading project is to be successful. Bad examples for these problems are ample, as for instance, a well dug in an eroded drainage line; eroded pathways which serve as open drains during downpours leading to wells, carrying rubbish thus polluting the well water; contents of pit latrines seeping into the groundwater which often is drawn from wells; houses being in danger to be undermined by gully erosion etc. Severe sheet and gully erosion is often due to poorly planned road alignments and insufficient stormwater control.
Any activities to implement development schemes with the objective to improve the water supply and water disposal situation have to be viewed in the light of serious internal difficulties:
3. The war situation which was particularly prominent in the North and which existed until 1989, resulting in the day-to-day survival of the local population, rather than in long-term visions. The war was also used by the Namibian Department of Water Affairs in being reluctant to improve the water supply situation in the North but was never reluctant to do so if it was required by the interests of the 'whites' and particularly the 'SA Defence Force and Police' and their "South West African" counterparts. The war situation was also used as an excuse in refusing to supply information regarding existing pipe systems, hydrology, water quality, demography data etc. in the past .
2.2 APPROPRIATE TECHNOLOGIES IN WATER SUPPLY SYSTEMS
2.2.1 BASIC DATA ON WATER
220.127.116.11 CLIMATE AND HYDROLOGY
Namibia's climate is strongly influenced by the cold Benguela current at its south-western Atlantic Ocean coast resulting in a mean annual rainfall of only 250 mm (between 50 mm in the S.W. and 700 mm in the N.E.) over the whole country. The average deviation from these figures may be as high as 80% of the mean annual rainfall in the dry south-western areas to as little as 20% in the north-eastern ones. Precipitations occur mainly during the summer months between November and April by means of very intense, but scattered thunderstorms in the late afternoon and at night. As stated above, the potential average annual evaporation varies between 3 700 mm in the central and southern regions to 2 600 mm in the north. Consequently it can be derived that where the rainfalls is at minimum, the evaporation is at maximum.
Namibia has in the average 10 hours of sunshine per day and the average daily temperature is 25oC. Absolute maximum and minimum temperatures can vary between -10o and +40o. These climatic extremes contribute to a unique hydrological cycle. It is estimated that on the average 83% of the total rainfall evaporates immediately, 17% is available as surface run-off, of which only 1% recharges groundwater sources and 14% is lost through evapotranspiration. Only 2% of the surface run-off are left to be used in surface storage facilities with irregular and unreliable river flows in the interior dry rivers.
The potential of surface water sources is therefore very limited. Against these climatic and hydrological data stands an increased demand for potable water at an average rate of 12% per annum since 1970. It is estimated that the annual water demand in Namibia will increase to 250 Mm3 by the year 2000. The total assured yield of both surface and underground water resources is estimated at 500 m3 per annum and 20% of this potential is already being used for human, animal, mining, industrial and agricultural purposes .
18.104.22.168 GEOHYDROLOGY AND WATER QUALITY
Groundwater resources originate from recent or prehistoric precipitations. They are therefore sensitive to exploitation and exhaustible. Groundwater can be used effectively if it is replenished by natural recharges. The availability of groundwater depends on a combination of sufficient precipitation and favourable hydrogeological conditions. Due to the generally arid conditions in Namibia, the emergence of groundwater as springs is very rare. The depth of the groundwater table varies considerably depending on the topography, geology and climate of the area. The occurrence of groundwater in Namibia is associated with six major geological environments:
The quality of groundwater is dependent on various factors like the rainfall, the topography and the chemical properties of the geological formations through which the groundwater percolates before it accumulates in an aquifer. The groundwater in the arid regions in the west and south of the country tends to have concentrations of soluble salts which may cause health problems for humans and animals. The highly corrosive nature of such water can also cause problems to water supply and disposal equipment, road drainage structures etc. The most important criteria for the quality of potable groundwater is the concentration of total dissolved solids, nitrates, fluorides, sulphates and total hardness. The water in the major surface storage dams is generally of a satisfactory quality with the total dissolved solids ranging from 80 to 800 mg/l. Normally this water quality only requires clarification and disinfection to render it suitable for human consumption. A comprehensive set of maps indicating the groundwater quality has been published by the Namibian Department of Water Affairs.
The chemical and physical guidelines for drinking water in Namibia are based on the guidelines of the World Health Organisation 'WHO' with some modifications based on the results of local expertise and research. The approved guidelines have been adjusted, within proven safe health margins, mainly to suit local conditions and to avoid inappropriate water treatment facilities. The micro-biological parameters for drinking water are in conjunction of the principles of the 'WHO'. The following table shows some of the more important determinants of the guidelines for approved Namibian drinking water quality.
TABLE 1 DETERMINANTS FOR NAMIBIAN DRINKING WATER GUIDELINES
| DETERMINANT | UNIT |---------------------------------------|
| | | GROUP A | GROUP B | GROUP C | GROUP D |
| | |---------|---------|---------|---------|
| | |EXCELLENT| GOOD |LOW RISK |HIGH RISK|
| | | | |OF HEALTH|OF HEALTH|
| CONDUCTIVITY | mS/m | 150 | 300 | 400 | > 400 |
| SULPHATE | mg/l SO4 | 200 | 600 | 1 200 | > 1 200 |
| NITRATE | mg/l N | 10 | 20 | 40 | > 40|
| FLUORIDE | mg/l F | 1,5 | 2,0 | 3,0 | > 3,0 |
SOURCE: Department of Water Affairs: SWA/Namibia: Perspective on
Water Supply in Namibia, Windhoek, 1989, p.5
NOTA: Regarding chemical quality 90,8% of the water supplied by the
2.2.2 THE PRESENT OVERALL WATER SUPPLY SITUATION
Namibia has currently 126 State Water Schemes which supplied 51,1 Mm3 of water for domestic and rural purposes during 1987/88. These State Water Schemes are mainly concentrated in the areas of the modern sector of Namibian economy. About 50% of this water supply was supplied from groundwater sources. More than 70 of the water schemes supplied less than 50 000 m3 per annum each and only 34 water schemes supplied more than 100 000 m3 per annum each. The largest water scheme supplied 9 Mm3 during 1987/88. 51,4% of the water supplied was used by primary consumers, 35,4% by irrigation and 13,2% by mines during 1988/89. According to sources of the Namibian Department of Water Affairs more than 70% of the population is supplied with potable water from water schemes provided by local, regional or central government administrations. The remainder of the population obtains water from boreholes, wells and the perennial rivers at the borders. The average per capita consumption of the population is about 100 litres per day. In succession it will be shown that in reality this picture is not so rosy.
The following table proves that Namibia's major dams are concentrated in areas where they are of importance for the interests of the modern economy but not so much for the bulk of the Namibian people in the rural areas in the North.
TABLE 2 INFORMATION ON NAMIBIAN MAJOR DAMS|==================================================================|
| DAM | CAPACITY (Mm3) | 95% SAFE YIELD |
| Hardap (Dist. Mariental) | 300,2 | 50,0 |
| Naute (Dist. Keetmanshoop)| 83,6 | 12,0 |
| Swakoppoort | 69,9 | 4,7 |
| (Dist. Okahandja) | | |
| Von Bach (Dist. Okahandja)| 50,0 | 6,9 |
| Omatako (Dist.Otjiwarongo)| 45,1 | 2,1 |
| Oanob (Dist.Rehoboth | 35,0 | 4,5 |
| Otjivero Combination | 17,6 | 1,4 |
| (Dist. Windhoek) | | |
| Dreihuk (Dist. Karasburg) | 15,5 | 0,0 |
| Friedenau (Dist. Windhoek)| 6,7 | 0,5 |
SOURCE: Department of Water Affairs: SWA/Namibia: Perspective on
Water Supply in Namibia, Windhoek, 1989, p.12
NOTA: Above table shows that on average only 13,2% of the water
22.214.171.124 THE PRESENT WATER SITUATION IN THE NORTH
As outlined above development activities for water supply systems should concentrate on the densely populated rural areas in North Namibia. In this study, the Ovamboland, the Kaokoland, the Okavango and the East-Caprivi Strip are considered the 'North' (In West-Caprivi District, there are hardly any communities). Despite the unfavourable situation as far as water supplies in these areas are concerned, the Namibian Department of Water Affairs doesn't use its resources accordingly. Large-scale water supply projects, especially benefitting the economic interests of the 'white' population group in Namibia and generally concentrated in the central parts of the country are currently undertaken. Namibia's north is getting low priority and even existing projects like the canal/pipeline schemes and the many excavation/ pump storage earth dams in Ovamboland, constructed in the 1950s/60s, are neglected. This is especially true for the rural areas. The administrative centres like 'White Oshakati', Rundu and Katima Mulilo, police stations and army bases are getting some more attention, as far as maintenance of the water supply systems is concerned. During the financial year 1986/87 on the above mentioned 'Eastern National Water Carrier' R 18.223.339 were spent. Out of the total 1986/87 capital-projects-budget of R 30.803.929 the Ruacana-Ondangwa canal/pipeline scheme and the Rundu water project were getting respectively R 84.705 and R 97.254, being the only beneficiaries of the whole Namibian north . This represents less than 6% of the expenditure of the Namibian Department of Water Affairs for more than half of the population, despite their already unfavourable water situation . Therefore, it is logical that 'N.G.O.s' like the 'C.C.N.' are concentrating their efforts on the Namibian north (and the Government of the Republic of Namibia since independence).
126.96.36.199.1 THE OVAMBOLAND
The canal/pipeline water supply system in Ovamboland runs mainly parallel to the
arterial roads in this region (M.R.92, T.R.1/11) and consists of a total of approximately
600 km of canals and pipelines . The densely populated areas along these trunk and main
roads from Ombalantu/Anamulenge/Nakayale in the north-west to Ogongo, Oshikuku, Okatana,
Oshakati, Ongwediva and Ondangwa, with branch pipelines from Ondangwa to Oshikango at the
Angolan border in the north and another line to a point north of Oshivelo in the south as
well as the Olushandja-Tsandi-Okahau branch pipeline, are supplied with drinking water via
the canal/pipe line system of the Namibian Department of Water Affairs (D.o.W.) from the
Kunene Scheme at Calueque/ Ruacana. Due to the closure of the water works at Calueque/
Angola the canal section from Calueque to Olushandja is lying dry momentarily (1989)(canal
capacity 6 m3/s, the so-called 'LTA'-canal built from rectangular concrete
blocks). The emergency pipeline from Ruacana to Olushandja supplies the full drinking
water demand for the D.o.W.-Ovamboland canal/pipelines scheme. This stand-by pipeline has
a capacity of 0,3 m3/s which will be increased to 0,63 m3/s by
booster pumps in the near future. The pipeline provides unpurified water to Mahanene at
the Olushandja dam (the Olushandja storage dam has a capacity of 42 x 106m3)
and further via the canal to Ombalantu. The Mahanene-Ombalantu canal (the so-called
'CONCOR'-canal built from trapezoid shaped interlocking concrete blocks) which normally is
fed by the Calueque scheme (after independence of Namibia this has to be negotiated with
the Government of the People's Republic of Angola) has a capacity of 3 m3/s
which, however, has never been tested by the D.o.W. At Ombalantu the 3 m3/s
canal from Ombalantu to Ogongo switches over to a canal with a capacity of 1,5 m3/s
and possibly more (the so-called 'new' canal with a parabolic crossection, built by the
Namibian 'D.o.W.' and commissioned during 1980), without any provision to make use of the
surplus capacity of 1,5 m3/s at Ombalantu . This problem has to be solved
in any water supply master plan in the future. The normal capacity of 3 m3/s
resp. 1,5 m3/s and the temporary one of the pipeline Ruacana-Olushandja is
sufficient for the drinking water demand of the Ovamboland Scheme .
TABLE 3 CANAL/PIPELINE SYSTEM IN OVAMBOLAND/NAMIBIA (D.o.W.)
NOTA: AC= Asbestos-cement pipes; HDPE/UPVC= Plastic pipes
In the rural areas, outside above outlined fragmented network of water supply pipelines, where the people live in 'kraals' dotted all over the country side, some 200 - 500 m apart, the situation is worse. Most people fetch (often polluted) water from wells or 'gorras' (open pits in the ground), which can be several kilometres apart from the settlements. Obviously, the situation improves during the rainy season between October and April, making use of ground dams in the oshanas (wide, open, shallow dry riverbeds), roof catchments and alike. But, the situation is still deplorable. The many constructed excavation and small pump-storage dams, fed by the 'efundja' (floods originating from the Cuvelai catchment area between Kunene and Okavango rivers) which had been built in the 1950s and early 1960s are neglected and in many cases in a sad state of disrepair.
188.8.131.52.2 THE KAOKOVELD
The sparsely populated district (population of approximately 20.000 only) in the far north-west of Namibia is in contrast to Ovamboland which can compete with the North-German plains as far flatness is concerned, is mountainous. While Ovamboland consists of alluvial soils of the Kalahari Group, the Kaokoveld is made of Precambrian rocks of the Vaalian, Mokolian and Namibian ages. Generally boreholes are representing here a feasible solution. The larger expenditure as compared to wells, however, will require information about the expected water tables, the water quality, the size of the aquifer etc. which tends to be better known with wells. In fact, also the interference between boreholes and the possible effects of the ecology have to be considered more seriously than done at the present point of time . Development to the communities in the Kaokoveld by the 'CCN Water Desk' concentrated during 1988/89 on assisting them with the repair of driving borehole pumps.
184.108.40.206.3 THE KAVANGO REGION
Another relatively densely populated area for Namibian standards, with approximately 130.000 inhabitants, is the Kavango region. The bulk of the population lives concentrated along the borders of the Okavango river. For instance, the water supply for the capital of Rundu is pumped from this river. Tough the water is near and in abundance, it needs expensive treatment, hence the present cost of R 0,48 per m3. This is regarded as too high for the bulk of the population of Rundu which lives in sight of the most concentrated water source in Namibia but cannot afford it. In the rural areas of the Kavango region a water treatment from the river is mostly not available. In spite of the mighty river, the lack of water is comparable with the situation in Ovamboland.
The Kavango region's mean annual precipitation lies between 550 and 600 mm. It has less oshanas (here called 'omurambas') and sand pans than Ovamboland. . Therefore, the underground water tends to have a lower mineral content, as it does not derive from evaporating stagnant pans. For this reason, there are more boreholes in the hinterland of the region, pumping the water from lower aquifers. There also exist good possibilities for shallow wells. Generally these will need lining (unconsolidated soils) and caisson-method below water level (to prevent running sands) .
220.127.116.11.4 THE EAST CAPRIVI
Apart from the district capital Katima Mulilo which derives its supply from the adjacent Zambezi river, and people living along the banks of the Zambezi, Kwando and Linyandi (Chobe) rivers, this region with ca. 60.000 persons faces water problems comparable to those of Ovamboland and the Kavango region. There is a pipeline along trunk road 8/6 Kongola-Katima Mulilo, but the reliability is reported to be low and, anyway, only limited to the immediate environment of this road. Another pipeline which was built by the 'S.A.D.F.' in the 1970s during the construction of trunk road 8/5 from Bagani to Kongola has fallen to complete disrepair.
The East Caprivi Strip is enclosed by rivers (Zambezi, Kwando-Linyandi-Chobe rivers), has a silty soil consisting of fine sand with clay particles of the Kalahari Group and a mean annual precipitation in excess of 600 mm. The potential for rainfed or irrigated agriculture is not even touched yet. It has the disadvantage of being farm from Namibian markets and the decision makers in Windhoek.
A local drilling contractor reported, the area east of Katima Mulilo has a high water table, while west of the capital the groundwater table is much lower. Consequently shallow wells are found in the east and deep boreholes (60-70 m depth) in the west, many with water yield problems. Apparently, water aquifers can be as small as only 50 m horizontally (so-called water pockets), running dry gradually. This should be a warning to implement a thorough research on the water supply situation in the East Caprivi. The turbidity, colour and taste of the water occasionally appears to be below standards. Possibly, the rusting of steel casings (reported by above drilling contractor to last only 6 to 8 years), caused surrounding sandfilters and soil to enter the borehole. It would be worthwhile to consider to make use of PVC pipes, though these have the disadvantage of breaking during transport, installation and improper pump handling .
2.2.3 NEW WATER SCHEMES IN THE NORTH OF NAMIBIA
18.104.22.168 THE OVAMBOLAND
Due to the population concentrations and the seriousness of the water supply situation in Ovamboland this study will concentrate on this so far neglected area of Namibia. Other regions in Namibia's north are not so seriously affected and were, as far new water supply schemes are concerned, already discussed in above sections.
22.214.171.124.1 TECHNICAL AND PHYSICAL CONSIDERATIONS
Ovamboland has a mean annual precipitation of approximately 450 mm. The flat oshanas should be an important source for irrigation purposes. Even if Ovamboland would have a much more complete drinking water supply pipeline system than it has today, this pipeline water would be limited in supply and too expensive for large scale irrigation. An impermeable soils layer in some metres depth permits the water to be retained in the oshanas for some months. Below this, the water quality differs, according to the area. North-east of a line which roughly runs parallel and approximately 50 km east of trunk road 1/11 (Oshivelo-Oshikango), it is of reasonable quality, except for high fluorite contents which could be purified. The sand at that depth is generally fine and deep wells therefore can only be made by the caisson method below water level. A more expensive alternative to wells would be boreholes.
In order to understand the current and future water supply situation in Ovamboland it is suffice to outline he hydrographic situation of this region and especially the contribution of the Cuvelai River to the hydrography of Namibia. The Kunene and the Okavango rivers are the two boundary rivers between Namibia and Angola .
Both rivers are perennial rivers with a period of maximum flows between February to July. In these times both rivers, during periods of exceptionally high floods can carry volumes of 6.000 m3/s, whereas during the period of minimum flow, the volume may be reduced to only 5 m3/s in the Kunene and 6 ms/s in the Okavango .
Starting from the Ruacana Falls at the Kunene, the border between Namibia and Angola runs along latitude 17o; 23'; 23,73'' south, to the Okavango rapids at Katuitui. This rectilinear border line, about 450 km long, cuts Ovamboland in two halfs, the southern one is situated in Namibia, the other one in Angola. This extensive region is in the north bounded by the Serra Encoco (approx. 1600 m in altitude) in Angola, approx. 290 km north of the Namibian border and in the south by the Etosha Pan, approximately 140 km south of the international boundary.
The climate is sub-tropical, particularly in the north. The rainy season is from October to May, but the highest precipitations occur during February and April. The few available meteorological data clearly show the increase northwards, from a mean annual precipitation of only 400 mm at Okaukuejo to 1.300 mm at Cassinga at the Chitanda River. Regions with an 'M.A.P.' of more than 1.000 mm in this part of Africa have perennially flowing rivers and streams. In the northern parts of Ovamboland, consisting of the Serra Encoco and the adjoining slopes in the south and the east to Mupa in Angola, lies the source of the flooding of Ovamboland, the 'efundja'. The efundja-fed river systems in Ovamboland are during the rainy season, in years of a good efundja, a veritable maze of water courses and pools, the above mentioned oshanas .
The river Cuvelai is the principal river with its western tributary, the Mui-Mui and its eastern one, the Caundo, both in Angola situated. The Oshana Etaka in the western part of Ovamboland follows a line Mahanene-Eunda-Onesi-Tsandi-Okahau to the Oussouk Pan where it joins the Cuvelai, the most southerly point of the flood areas of Ovamboland. From here a definitive drainage takes place down the Ekuma to the Etosha Pan which is endoreic, i.e. an inland drainage system. The most easterly of the oshanas, the Oshana Oshigambo, is silted up over long stretches and it reaches Etosha Pan only in exceptionally good rainy seasons.
The catchment area of the Cuvelai system up to a line Oshikuku-Okatana-Oshakati- Ongwediva- Ondangwa is 37.200 km2, in comparison to the Swakop Dam at Okahandja with 2.750 km2 and the Fish River at the Hardap Dam with 13.000 km2. The velocity of the water in the oshanas hardly exceeds 0,5 m/s and is dependent on many factors. Backflowing is due to the extreme flat slopes in Ovamboland possible, when the down coming oshana, at a certain flood height, may slowly fill up a dead river branch in a reverse, northerly direction.
The sharply fluctuating water conditions of the Cuvelai catchment area between good and bad rain years, from flood to severe drought, had since the turn of the century gave rise to many water supply projects in Ovamboland . For the first time in 1927, a programme of dam-building was carried out in Ovamboland by the SWA Administration, after a series of dry periods. The dams were dug out by hand and had therefore only a limited capacity insufficient to last the whole year. Since 1954 a new dam building programme commenced which included not only a system of excavation and small pump-storage dams but also a canal system feeding some of these dams. The whole oshana system from Okatana to Ogongo, in a north-westerly direction, had been cut through by a ground canal, through which the water supply of this region could be directed and controlled. It was planned to connect this system of excavation and pump-storage dams which were built in the 1950s and 1960s with the Kunene via a high capacity canal system. It was further planned to develop large scale irrigation by such a comprehensive water supply system for the densely populated areas of Ovamboland and by this, the ever recurring famine following upon the droughts could be done away with. The irregular efundja is a major blessing for Ovamboland. Together with the utilisation of the Cuvelai and the Kunene rivers by a system of dams and a comprehensive drinking water pipeline system for the whole of Ovamboland, this could be a key to a prosperous development of this so far neglected region of Namibia.
The first five years plan between 1954 and 1959 saw the completion of the following water supply systems in Ovamboland: 4 pump storage schemes including 9 dams, about 10 km of unlined ground canal, pump houses, filtration plants, wells etc., all serving the water supplies in Okatana, Ondangwa, Oshikuku and Onandjokwe, further 2 canal excavation dams with ferries, 32 excavation dams for livestock, 8 with pump storage capacity of 47.000 m3 each and 7 with 32.000 m3 each, 43 storage road culverts etc. During 1958/59 there have been 80 dams in operation and 1959/60 96 dams in Ovamboland.
This system proved very soon to improve drastically the water supply situation in Ovamboland. For instance, during the rainy season 1959/60 the floods of the western oshanas filled all the depressions up to the Etosha pan but the pan itself got no water, and for the third consecutive year the Cuvelai did not come down. The first completed sections of the Ovamboland ground canal showed its first result when it carried water to the Cuvelai from the western oshanas. This water reached the Okatana dam where pumping immediately started. The irrigation dam was pumped up to 6 feet deep. This volume of water was about 100.000 m3 and made possible the first irrigation experiments in Ovamboland.
The so-called 'Stengel Dam' west of Omboloka in North-East Ovamboland seemed specifically to be the model of a success but it also posed new problems through those years. From 1955 to 1958 it was never empty and reached its lowest water level of approx. 3,50 m in October 1955, the highest level being about 6 m. The water which was at first good became later turbid and was undrinkable for people and livestock. After some pumping during August 1959 it was thought that natural evaporation would empty quickly the dam but, surprisingly, it was found that the rate of evaporation was exceptionally low, probably on account of the muddy water. This fact which could be of high significance for a country with staggering evaporation losses of between 2.500 mm and 2.900 mm per annum , was apparently never systematically investigated and should be a candidate for thorough research after independence as it may be a solution to the problem of evaporation .
The second five year plan from 1959 to 1964 provided for the building of a canal from the Kunene southeast across Ovamboland to Okatana (Oshakati). The canal cut across the oshanas flowing from north to south, so that each good rainfall north of the canal causes one or more of the oshanas to come down as a contributory of the canal. It was the original idea of this sound engineering solution to irrigate many thousands of hectares on both sides of the canal and serve 430.000 hectares of fenced in grazing. The establishment of some small industries as meat canning, bone meal, tanning and furniture factories were deemed to be feasible as a secondary product of the Ovamboland water scheme.
Unfortunately, due to the incorporating of the so far autonomous Namibian Department of Water Affairs into the South-African Department of Water Affairs during 1969 , the promising beginnings of a system of excavation and pump-storage dams together with the Ovamboland canal/pipelines schemes were never completed according to the originally proposals. The already during the 1950s and 1960s constructed dams were neglected and are presently in most cases in a bad state of disrepair. The original Ovamboland canal from Oshakati to Ogongo is at the present point of time poorly or not at all maintained and during the rainy season a succession of pools of stagnant water. The drinking water canal/pipeline system fed by the Kunene was completed only so far as it was of any value for the administration of the country and the economic interests of mainly one population group, thus failing the original concept of using the efundjas for large scale irrigation in Ovamboland.
126.96.36.199.2 PROPOSED WATER SUPPLY SCHEMES
In the central and western parts, south-west from a line running approximately 50 km north-east of trunk road 1/11 between Oshivelo and Oshikango, the bulk of the Ovamboland population lives. There is an abundance of groundwater at shallow depths but most of it is saline or brackish with water containing over 10.000 ppm in many cases. Water of potable quality occurs at small lenses above the saline water and is usually quickly exhausted. Thus all over the Cuvelai area one sees strings of holes which have been dug to obtain drinking water. As the water in one hole becomes saline so another is dug elsewhere. Boreholes and wells seem therefore not to be the ideal answer.
Besides a comprehensive pipeline network within easy walking distance for the points of population concentration the revival of neglected and disrepaired and the new construction of excavation and small pump-storage dams fed by the efundja should be the medium to long term solution. Reliable high quality drinking water, however, should be obtained from the Kunene and Okavango rivers along the border with Angola. These rivers have flows which are enormous but not unlimited and in any case to be negotiated with the People's Republic of Angola, relative to Namibia's water demand. Technically, as outlined in above table, water is already pumped to a small area of Ovamboland. This scheme has to be considerably extended, water can be pumped from either of the two border rivers, disinfected and piped to the communities. As also acknowledged above, this grand scheme will still take many years to come, even now with the independence of the Republic of Namibia. Hence, it will be important to investigate the old system of excavation and pump storage dams and even wells and boreholes, where no other alternative is feasible at the short-term .
Evaluating the current water supply situation in Ovamboland and evaluating small water community projects undertaken by the CCN it soon appears that little has been done in respect of quantifying the water needed for the specific community and investigating all alternative water availabilities as well as the likely production of proposed wells or boreholes. It has also to be mentioned that due to stringent staffing problems at the 'CCN-Water Desk', little attention is so far given to train respective communities and to encourage more community training and participation. Below follows a list of different small water supply projects at grass roots level, currently undertaken by the 'CCN Water Desk' in Ovamboland. These project descriptions indicate clearly some of the difficulties which can be encountered with the formulation of similar projects in the future :
1. Okahua 1
All these projects are situated in the vicinity of Engela near the Angolan border at Oshikango. In general, all these wells were dug by the local communities, while they were assisted with the more technical works like concreting by the 'CCN Water Desk'. All the building materials were supplied free of charge by the CCN. It can be expected that these communities will also need some assistance financially in the maintenance phase of the project for the first years. This will be especially the case for those equipped with pumps driven by an engine, hence the need to consider hand pumps, windmills or solar-panel driven systems.
But, as mentioned above, the long-term solution lies in a comprehensive combined scheme of the extended pipe/canal system, fed by the Kunene and probably at a later stage by the Okavango, for drinking water for people and livestock and the revived and extended system of excavation and pump storage dams in combination with a re-activated ground canal fed by the efundjas from Ogongo to Oshakati all over the densely populated areas of Ovamboland for irrigation purposes. The revived and newly to be constructed system of excavation and pump storage dams as well the re-activated ground canal should be initiated on the same basis as the small grass roots water supply systems currently undertaken by the water desk of the CCN. It will, however, be beyond the technical and financial scope of the CCN to tackle such a scheme and should be incorporated into the water supply master plan for Ovamboland, initiated by the new state of an independent Namibia. In order to revive such a dam scheme for mainly irrigation purposes, fed by the efundja, the technical aspects of such a scheme will be highlighted below.
This scheme should consist of two distinct steps: Firstly to extend the current modern canal/pipeline system fed by the Kunene in order to supply drinking water to the bulk of communities in Ovamboland and secondly to revive and extend the neglected existing system of excavation and pump storage dams in combination with the old ground canal between Ogongo and Oshakati fed by the efundja in order to create a comprehensive agricultural irrigation system in Ovamboland.
Excavation dams can be dredged at suitable places at the edges of oshanas/omurambas or pans and whilst the oshanas and pans only held water for a few months at a time, these excavation dams should normally not dry up at all, if correctly designed. The dam basins should never be placed in the main water course but next to it. The danger of silting-up is consequently minimised. It is also minimised if the dam basins are constructed on the flood plain adjacent to a main water course or in the funnel-shaped mouth of a smaller tributary. In both cases the dam should be connected to the main water course with an inflow canal. The dam fills in the following way: some of the water flows through the inflow canal into the basin. If this is full no further water flows into it even at high flow because the water level in the dam basin is the same as that in the main water course at the dam inlet. The design for such an excavation dam should be as such that even the strongest high flood can be diverted down the main river course without causing any damage.
Three dam types were designed during the 1950s and 1960s for the Ovamboland water scheme: 1. The excavation dam with feeder canals; 2. The road culvert dam in the Oshanas; and 3. The pump-storage dam with feeder canals and filter plant where necessary for drinking water purposes. The depth of the pump storage dam should be in the region of 10 m and the pump sump 5 m deep .
On the principles of these designs the efundja-fed system of a water supply scheme of excavation and pump storage dams combined with a ground canal cutting the oshanas should be re-designed and re-implemented as a basis of an extensive irrigation system for Ovamboland, under the proviso that a correct crop choice for the specific soil conditions of the regions will be made.
Solar distillation is a well developed technology in many parts of the world which, surprisingly, was not used so far in Ovamboland where there is no shortage in solar energy and an abundance of saline water. Small, simple fibreglass stills could be easily made available which could be suitable for use at individual homesteads al over Ovamboland. The local manufacture of various models of solar still should be promoted on grass roots level combined with training possibilities, new job opportunities and improved water supplies.
The principle of this method is that the salt water runs in a special groove of partly dug in drain pipes. The solar rays will heat the water, which will evaporate and condense at the bottom of the pipe. This system can be used for drinking water distillation but the drain pipe can be, for instance, also constructed for dripping purposes and placed along crop fields. Other low-cost and low-energy methods for the supply of water can be based on the desalination process of reverse osmosis. The principle of the reverse osmosis process is that the water flows over membranes. All dissolved materials are retained by these membranes. This means that the raw water is divided into two streams, pure water (the permeate) and a concentrate containing all dissolved solids.
The energy consumption for both systems is low, although in many cases where no arthesic water is at disposal, pumps have to be used. The normal energy consumption is 4 kgW per m3. The advantage of both methods is that the water is not only desalinated but also purifies, for instance sulphates are eliminated. Ion exchange is another possibility, however, the costs involved are prohibitive .
There is also a great need in Ovamboland for appropriate water harvesting and storage systems at the homestead level. Again, use should be made of suitable technologies which have been developed and used in other 'IDCs' in Africa. They need to be tested in Ovamboland and thereafter their use promoted. These appropriate water supply method could be a supplement for those smaller communities which are too small that it could be afforded to connect them to the drinking water pipeline system.
2.2.4 THE PRESENT WATER SITUATION IN THE SOUTH
Although, generally, the so-called 'modern' areas of Namibia in the central and southern parts of the country are much better off than the regions in the north, there are nevertheless some impoverished areas in the Namibian south which also need attention. The target groups are the scattered communities mainly in Namaland. The required assistance are new or re-activated small water supply schemes for people, large and small livestock and sometimes communal gardening projects. The Namibian 'Interims' Government' also provided water on a small scale to those communities but had set certain conditions. The communities being fully aware of the South African strategies behind such 'assistance' rejected it in several cases .
2.2.5 NEW WATER SCHEMES IN THE SOUTH OF NAMIBIA
Many of the mentioned parameters for the northern regions are also valid for water supply community projects in the south. The assistance offered by the 'CCN Water Desk' often concerns ongoing or re-activating water supply systems to people, cattle and sometimes small communal gardens. In general, less guidance is needed than in the north, as some experience has been built up over the years. To encourage self-reliance, the 'CCN Water Desk' has revised its strategy for 1989 and will request the communities in Namibia's south to cover 30% of the costs of the equipment and building materials needed .
Some case studies which were investigated by 'Namibia Consult Incorporated' under the auspices of the Namibian churches and the 'C.C.N.' are reported below. One of the envisaged projects is a community project of 'A.M.E.C.' to create an irrigation scheme for communal gardening for the impoverished community of Gibeon .
The Gibeon ground dam is a proposed small dam structure in a side arm of the Fish River to provide irrigation water for above irrigation project for the 'A.M.E.C. Water Project' at Gibeon. The ground dam is situated in the 'Gibeon Reserve' about 2 km upstream of Gibeon, approx. 8.0 m upstream of the crossing of district road 1088 with the Fish River. For the ground dam a height of 5,0 m is proposed. The site of the proposed dam is ideally situated in a fairly deep side arm of the Fish River which is separated from the main course of the river by a several metres high island, approximately 1 km long and between 200 to 300 m wide. At the southern top of the island there is an ideal dam site. From this point of the storage basin the irrigation water can be pumped to the communal gardens by means of solar-driven pumps.
The proposed A.M.E.C. Water Project has the aim to create the basis for a development project for the community of Gibeon to start an agricultural cultivation project for the growing of vegetables and other useful plants. In order to realise such a project irrigation has to be established. Gibeon is one of the biggest settlements in the south of Namibia and will have an estimated population of more than 5.000 in the year 2000. Gibeon is situated along the Fish River, the biggest river in the Namibian inland, approximately 60 km south of Mariental and 170 north of Keetmanshoop. A high standard gravel road, main road 32, connects Gibeon with the railway station Gibeon as well as with the great north-south trunk road 1/3 which by-passes Gibeon approximately 8 km to the east. Gibeon lies at an altitude of 1.050 m above sea-level.
Due to the serious water situation of Gibeon, the existing water supply will not be able to provide for any irrigation water outside the scope of the already stressed drinking water supply for the Gibeon community. Therefore, it has to be investigated whether it will be technically feasible to use an existing side arm of the Fish River to create an artificial storage basin for irrigation water. A small earth dam structure in this side arm, between the steep embankments of the Fish River on the east side and an island in he middle of the river, will create a storage basin which could provide for irrigation water for the project. The proposed cultivated lands are placed in the vicinity of the proposed dam which is situated approximately 5 km north of the Fish River low water bridge at Gibeon (on district road 1089).
Other appropriate technology tasks for water supply or water applied schemes were undertaken by the 'CCN Water Desk'. In the southern regions of Namibia these activities concentrate inter alia on communal gardening. In many cases there are crucial water problems in terms of quality and availability due to natural factors. But, lack of co-operation from some of the local communities and a general decrease in community support and participation is a cause for grave concern. It should be especially investigated to involve water-based communal garden projects into school activities and combine activities like tilling, weeding and cultivating with their school programmes, for gardening to become part and parcel of the curricula and/or to be tackled on a part-time basis.
Water supply projects in the south and the east tackled by the 'CCN Water Desk' were inter alia the following :
2.3 SUMMARY AND CONCLUSION
Namibia is a semi-desert country and water is most probably the most influencing development factor. No real general census of water exploitation or consumption has, to the knowledge of the author, as yet been undertaken on a nationwide scale. One of the difficulties is that many consumers, especially in the rural areas, do not know how much water they use or, where storage works are involved, how much of the stored water is usefully consumed and how much is evaporating. This factor contributes to the general difficulties of many unbalanced and un-appropriate water supply and water disposal schemes throughout Namibia. Generally there is no shortage of water in Namibia but the water is very unevenly distributed. For example, there is almost unlimited cheap, high quality water at the banks of the Okavango and Zambezi rivers, but it would be very uneconomic to bring this water to, say, Keetmanshoop in the south. This has an important implication for the overall planning of urban and rural development in independent Namibia.
In conclusion, the general development parameters can maybe be formulated as follows :
These are long-term objectives. In the short term urgent issues will be ones of priorities between above objectives which cannot be fulfilled simultaneously, e.g. the faster the water supplies are expanded, the larger the needs for staff and so longer it will take to localise alternative appropriate water supply schemes. The new government of an independent Namibia has to prioritise between different demands, e.g. are the needs of people living on scattered agricultural communities or in urban squatter settlements to be attended first? In many cases the new government will be confronted not only by arguments of relative costs and available funds and the ease of doing things, but also by the strength of popular demand for different things which cannot be tackled simultaneously. This process requires a framework of consultations between all concerned communities in order to realise really appropriate water supply works.