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' [1] 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 [2].

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 [3]. 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 [4].

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:

1. Technical difficulties like no perennial rivers in the Namibian inland (except Kunene, Okavango, Chobe and Zambezi rivers in the north as well as the Orange river in the south, Namibia's border rivers), a very low and unreliable rainfall season (50 - 700 mm per annum in the average), an extremely high evaporation rate (between 3.700 in the central-southern area to over 2.600 mm in the northern areas per annum), in many places unsuitable (saline) ground water and soils, a rural population which lives not in confined settlements - especially in Ovamboland, the Okavango and the Caprivi Strip, but in 'kraals', scattered all over the country side, with the resulting large numbers of distribution points, organisational problems like the vastness of the country and the unbalanced transport infrastructure, many different languages and, maybe most important, the low level of 'Community Organisation'.

2. The past governments in Namibia which geared their infrastructural policies mainly to the interests of one population group only and which were indifferent to the fate of the indigenous population.

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 25^oC. Absolute maximum and minimum temperatures can vary between -10^o and +40^o. 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.

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:

- Secondary Structures

Many parts of Namibia are covered by geologically very old Precambrian rocks which are inherently impervious. Groundwater can be found in these formations along joints, bedding planes, shear zones and faults. Secondary structures are mainly existent in folded areas and occur in practically all pre-Kalahari formations. The majority of stronger boreholes in these rocks are encountered on faults.

- Carbonate rocks

Carbonate rocks like limestone, dolomite and marble posses in many cases solution cavities which can contain fair quantities of groundwater. These Karst features are caused by carbonic acids which are forming when percolating rainwater dissolves carbonates. Such cavities develop thus more readily along faults, joints and bedding planes. Good groundwater sources in these rocks can inter alia be found in the dolomitic Karst areas in the Grootfontein-Tsumeb-Otavi area, in the dolomitic areas around Outjo and in the marble bands around Otjiwarongo.

- Volcanic Intrusions

Throughout the isotopic ages of the geological history of Namibia volcanic magma has intruded the older formations in the form of pipes, dykes and sheets. The contact areas of these intrusions are in many cases water bearing. For instance, in the southern regions more than 80% of successful boreholes outsides the artesian area were drilled along dolerite dykes.

- Porous Sediments (Artesian areas)

The most important sandstone aquifers in Namibia can be found in the Auob and Nossob sandstones of the Karoo Sequence, occurring in the central south-eastern region in an artesian basin which is called the 'Stampriet Artesian Basin'. Smaller artesian aquifers exist in the lime- and sandstones of the Schwarzrand Subgroup of the Nama Group west of Maltahöhe and in the basal gravel beds of the Kalahari Group sediments in an area north-west of Tsumeb.

- Unconsolidated to Semi-Consolidated Deposits

Approximately 30% of Namibia is covered by aeolian sands and unconsolidated to slightly cemented sediments. These include the Kalahari beds in the northern and eastern parts as well as the deposits of the Namib Desert along the Atlantic coastline. Where the rainfalls are sufficiently high (mainly in the areas of the Kalahari Group and not so much in the Namib Desert) these deposits may contain groundwater. These areas are specifically these with the highest population densities in Namibia (Ovamboland) which have the largest water supply problems.

- Stream Bed Alluvials

Substantial thicknesses of alluvial material have accumulated in parts of the large ephemeral rivers. These sand-filled riverbeds are important sources of groundwater since they are periodically recharged by floods. The most important aquifers of this type can be found in the Swakop, Kuiseb, Omaruru, Khan and Oanob rivers. In the stream bed alluvials the groundwater is mostly close to the surface.

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.

NOTA: Regarding chemical quality 90,8% of the water supplied by the
Namibian Department of Water Affairs in 1988 conformed to
Group A, 8,4% to Group B and only 0,7% to Groups C and D.
This statistics as supplied by the Department of Water Affairs
is most probably only relevant for the modern sector of the
Namibian economy (for instance not for the rural areas in Ovamboland).

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.

NOTA: Above table shows that on average only 13,2% of the water
stored in a dam is utilised in terms of the safe yield.
As all the dams are not fully utilised at this stage, the
total efficiency of the dams varies between 8% for Naute
and 62% for the Von Bach Dam.

|==================================================================|
| CANALS/PIPELINES                     | LENGTH (km) | DIMENSIONS  |
|--------------------------------------|-------------|-------------|
| Calueque - Mahanene Canal (Main)     | 24,00       | 2,8 m wide  |
| Ruacana - Mahanene Emergency Pipeline| appr.44,00  | 711 steel   |
|                                      |             | 700 AC/12   |
| Mahanene - Ombalantu Canal (Main)    | 36,50       | 2,2 m wide  |
| Ombalantu - Ogongo Canal (Main)      | 34,28       | 2,2 m wide  |
| Ogongo - Oshakati Ground Canals      | 40,00       | 1,0 m3      |
| Ogongo-Okahao (planned,not built yet)| appr.47,00  |             |
| Mahanene-Eunda Pipe                  | appr. 7,00  | 250 AC      |
| Eunda-Onesi Pipe                     | appr.10,00  | 250 AC      |
| Onesi-Uukualuudhi Pipe               | appr.45,00  | 300 AC      |
| Uukualuudhi-Okahao Pipe              | appr.35,00  | 100; 250 AC |
| Ogongo - Oshakati Pipe (Main)        | 40,00       | 600; 800 AC |
| Oshakati - Ondangwa Pipe (Main):north| 35,00       | 250 AC      |
| Oshakati - Ondangwa Pipe (Main):south| 35,00       | 500 AC      |
| Ondangwa - Okatope - S.E. Main pipe  |110,00       | 400-300 AC  |
| Ondangwa - Indangungu Pipe (Main)    | 20,00       | 315 AC      |
| Indangungu - Omakango Pipe (Main)    | 20,00       | 315 AC      |
| Omakango - Omafo Pipe (Main)         | 20,00       | 225 HDPE    |
| Omafo - Oshikango Pipe (Main)        |  6,00       | 160 HDPE    |
| S.E.Pipe - Onayena (branches off)    | 10,00       | 400 AC      |
| Ondangwa - Onandjokwe Pipe           | 10,00       | 100 AC      |
| Ondangwa - Ondangwa Airport Pipe     |  4,00       | 150 AC      |
| Ondangwa - Oshitayi Pipe             |  5,00       |  90 AC      |
| Okatope-Onjamba-Omuntele-Ambende Pipe| +/- 25,00   | not known   |
| Onandjokwe - Oshigambo Pipe          | 15,00       |  75 AC      |
| Onandjokwe - Orokonja Pipe           | 15,00       |  90 AC      |
| Indangungu - Oshigambo Pipe          | 12,00       | 160 UPVC    |
| Omakango - Endola Pipe               | 20,00       |  90 AC      |
| Omakango - Onambutu Pipe             | 40,00       | 217 HDPE    |
| Omafo - Ongenga Pipe                 | 25,00       | 160 UPVC    |
| Omafo - Engela Pipe                  |  5,00       |  50 AC      |
| Ongenga - Omungwelume Pipe           | 10,00       | 90 UPVC     |
| Omafo - Oshandi Pipe                 | 27,00       | 217 AC/HDPE |
| Oshandi - Eenhana Pipe               | 20,00       | 180 HDPE    |
| Eenhana Pipe - Ondobe Pipe           |  9,00       |  50 HDPE    |
| Oshikango - Odibo Pipe               |  7,00       |  75 AC      |
|==================================================================|
SOURCE: Developed by author out of fragmented data obtained from
different sources within the Namibian Department of Water
Affairs for 1989

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.

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.

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 [15].

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 m^s/s in the Okavango [16].

Starting from the Ruacana Falls at the Kunene, the border between Namibia and Angola runs along latitude 17^o; 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 [17].

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 [18], 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 [19].

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.

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 [21].

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 [22]:

1. Okahua 1

This project, consisting of a well capped with a 'Climax' handpump and a cattle trough was completed in 1987. There is a fair supply of water with good quality, though there are some shortcomings in the construction of the apron and soakpit.

2. Oshitambi

Here a windmill, type 'Suiderkruis', wheel diameter 3 m, fitted on a 12 m steel tower, is capping a shallow well. The location of this well in a low point of an oshana appears to be less suitable, but was determined by the local people. The quality of the water is apparently acceptable to them, but could be better if another site would have been chosen. No storage tank at the windmill exists as yet.

3. Ohaingu

This ongoing shall well project, fitted with a 3" 'Climax' hand pump is very near completion. There is some room for improvement as far as the trough and the drainage are concerned. It would also be advisable to be able to lock the manhole cover in the apron, to prevent children falling into the well and avoiding sabotage.

4. Onambango

Unlike above mentioned wells, of which the lining was made of concrete, this one is of cemented bricks. Communication problems between the 'CCN Water Desk' and the local builders resulted in an apron which will not fit the well. This could be rectified by increasing the diameter of the well over the last couple of metres, instead of decreasing it.

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 [23].

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 [24].

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 [26].

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 [27].

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 [28]:

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 [29]:

- to meet the basic needs of all Namibians for adequate water for drinking, washing and other domestic use

- to provide and maintain a reliable supply of water for agriculture, mining and industry

- to train Namibians swiftly as to localise and use optimally the restricted water resources in the country