Sourcebook of Alternative Technologies for Freshwater Augumentation in Africa

Table 2: SUMMERY EVALUATION OF ALTERNATIVE TECHNOLOGIES FOR FRESHWATER AUGMENTATION IN AFRICA

AGRICULTURE (WATER HARVESTING)

Technology	Extent of use	O & M	Level of involvement	Costs	Effectiveness	Suitability	Advantages	Disadvantages	Cultural Acceptability	Comments and Recommen-dations	Environmental Impact
Planting Pits ZAY/ZAI	Moderate	Low	Community	Low	High	Semi-arid degraded land	Simple Higher yields		Highly acceptable	Requires more promotion
Demi-Lunes or semi-circular hoop	Widely in Kenya and Niger	Low	Community & Extension workers	Low	High	200 - 800 mm rainfall	Cheap Easy Improved vegetation	Takes time, not suitable for mechanisation Can break with high runoff	In highest population densities but low in pastoralists	Further research in yield Labour inputs on rainfall	Increases vegetation cover on degraded lands
Katumani pitting	Kenya	Low	Community	Moderate	Very high	Grazing lands-500-800 mm of rainfall	Improved grazing and crops	Labour intensive	No cultural problems	Needs wider promotion	Rehabilitation effect on river course and water quality
Permeable rock dams	Burkina Faso	No Data	Community, NGOs, Government	High	Very high	Less than 700 mm of rain Local supply of stones Valley bottoms slope <2%	Increased crop production Erosion control Improves soils Controls gulley formation	Cost of transport (stones) Large quantities of stone required	Acceptable	Requires technical advice	Positive effect on river course and water quality
Contour stone bunding	Burkina Faso, Mali	Low	Community	Low if stones are readily available	High	Semi arid 700-800 mm of rainfall Stone available Wetter areas to prevent overgrazing	Simple Increased inland use	Leads to shortage of stones High cost transport of stones	Highly acceptable	Extension support required. Research in eventual silting required	Rehabilitation of degraded land and reduction of soil erosion
Tied contour ridge	Moderate	Low	Government, NGO, Community	Low	High	Variety of climatic and soil conditions Water shortage and severely degraded areas	Low cost Both mechanical or labour possible	Labour intensive Low planting density	Acceptable	Required effective promotion	Land rehabilitation and reduces soil erosion
"Fanya-juu" terracing	Morocco, Kenya	Moderate	Community	Moderate	Very high	>700 mm if rainfall Deep soils slopes < 5%-50%	traditional method Increase in crop yields	Labour costs high	Highly acceptable	Promotion in other areas required	Effective control of erosion
Flood harvesting using bunds	Somalia	Low	Community	No data Low	High	150-300 mm of rainfall Clay soils	Simple Improved food security	Results in occasional water logging and bund breakage	Highly acceptable	Introduces contour surveying and research in optimum spacing of bunds and positioning of spill ways	Poor management of flows can lead to erosion
Earth bunds "Teras"	Sudan	Low	Community	No data Low	High	150-400 mm of rainfall	Farmer managed Soil and water conservation	Lack of spill ways	Acceptable	Develop spillways to improve efficiency and reduce operations & maintenance	Reduces degradation
External catchments using contour ridging	Niger, Kenya, Egypt	High	Community, NGO, Government	Moderate	Very high	350-650 mm of rainfall Reclamation of degraded land	Increased More reliable crop production	Labour intensive Community not fully involved	Not fully assessed	Need demonstration and promotion involving the community	Reduction of soil erosion
Sand abstraction	Zimbabwe, Botswana, Libya, Algeria	High	Private sector, Government, Communities	High	High	Sandy river beds, usually seasonally dry	Reliable source of water Ranges from small to large scale	Capital cost high sand can shorten life span of equipment	Highly acceptable	Research relating various productivity parameters required	Over abstraction may reduce downstream flows
Lagoon front hand-dug well irritation	Ghana	Low	Community	Low	Locally appropriate and effective	Good shallow groundwater	Local materials Local skills Income generating	Shallow wells may dry up	Acceptable	Studies needed on saline intrusion	None expected
Sub-surface dams, small dams, sand dams	Kenya, Zimbabwe, Egypt, Libya, Tunisia, Algeria	Low	Local agencies	High	High	Sandy seasonal rivers prone to siltation	Good quality water Encourage silt deposition and water filtering Crop production made possible	Mainly limited to drinking water augmentation	Acceptable	Need to promote the technology more	Reduction of erosion, silt deposition and increased moisture infiltration
Cloud seeding	Zimbabwe	Very High	Government Community	Very high		Limited rainfall Agriculture a major commercial activity	No long term effect on weather Politically attractive Equipment can be put to other use	Depends on weather High expertise required A belief that rain would have fallen anyway	No cultural problems	Better indicators of impact of cloud seeding	No expected environmental effects
Tidal irrigation	Gambia	Low	Government Community	Very high	Very successful	Where river is in relatively flat basin with high tide intrusion	Low operation and maintenance Income generating for community	Unavailability of spare parts	Acceptable	No further development foreseen

AGRICULTURE (WATER QUALITY UPGRADING)

Technology	Extent of use	O & M	Level of involvement	Costs	Effectiveness	Suitability	Advantages	Disadvantages	Cultural Acceptability	Comments and Recommen-dations	Environmental Impact
Utilisation of artificial wetland for wastewater treatment	East and Southern Africa	Low	Community Government	Low	High	Small communities up to 5000 people treatment of waste water from towns, mine drainage, livestock, production, paper mills, tannerles, food processing plants, etc	Not dependent on external energy or chemicals Low operations and maintenance Effluent can be used for irrigation	Possibility of increased salinity	Acceptable	Important to ensure acceptability before promoting the technology More research in design and operation required	Aesthetically pleasing on the type of plants chosen Wetland can be a home for a wide range of birds and plants Can be used for recreation

AGRICULTURE (WATER CONSERVATION)

Technology	Extent of use	O & M	Level of involvement	Costs	Effectiveness	Suitability	Advantages	Disadvantages	Cultural Acceptability	Comments and Recommen-dations	Environmental Impact
Conservation tillage	Eastern and Southern Africa	Low	Government, community, NGOs	Low	High	Most soils and slopes-strip cropping well drained soils and slopes of 6-15% Contour farming, slopes of 3-8%	Soil erosion and runoff control Conserves moisture Mulch and strip improve soils	Strip and mulch can harbour pests Special skills may be needed for contour Cost of chemicals can be high Require use in combination	No cultural norms against	Promotion required	Conserves soil moisture and reduces soil erosion Chemical use under zero tillage can be harmful to environment
Deficit irrigation	Zimbabwe and South Africa	Low	Government Community	Inadequate data		Where water if limited	Conserves water There will be some harvest	The yield depend on percentage deficit and will always be less than optimal		Further research on how this could be combined with water harvesting required	Conserves water and enables plants/crops to be grown
Savanna wetland cultivation	Zimbabwe and Tanzania	Moderate	Community	Low	High	Shallow seasonally water logged depressions	Small scale approach most suitable Provides food security, and drinking water in the dry season		Acceptable	There is high potential for expansion in Africa The impact on the environment should be further investigated
Plans for water conservation gardening	Household level Africa wide	Low	Community	Low	High	Urban water conservation	External water supply Simple	Knowledge of plants required	Acceptable	Promotion of appropriate plants needed	Promotes use of indigenous plants
Porous clay pots and pipes	Zimbabwe	Low	Community Government	Low	High	<500 mm of rainfall	Cost pf pipes low Reduces weed problems Can be used for several seasons	Initial high labour input Porosity of pots decreases with time		Need to market this strategy	Conserves water

AGRICULTURE (WASTEWATER TREATMENT AND REUSE)

Technology	Extent of use	O & M	Level of involvement	Costs	Effectiveness	Suitability	Advantages	Disadvantages	Cultural Acceptability	Comments and Recommen-dations	Environmental Impact
Wastewater reuse	Widely used	Moderate	Local authority Government Farmers	Low to the farmer	High	Cultivation of fish Irrigation Agriculture	Reduces amount and use of other artificial fertilizers Polishing ground for the removal of nutrients Low cost nutrient water to farmers	Can use pollution Effluent contains pathogens Significant mechanisation required	General social aversion to close association with excreta	There is need for further promotion of the technology	Reduces further exploitation of fresh water Pollution of environment possible especially if waste water is not properly managed

DOMESTIC WATER SUPPLY (WATER HARVESTING)

Technology	Extent of use	O & M	Level of involvement	Costs	Effectiveness	Suitability	Environmental Implication	Advantages	Disadvantages	Cultural Acceptability	Comments and Recommen-dations
Protected springs	Extensively used	Low	Community Government, NGOs	Low capital and recurrent	High	Areas with springs	Prevention of soil erosion	Low cost Appropriate	Low services level	Highly acceptable	High potential and should be promoted
Rock and roof catchment systems	Extensively used	Low	Community Government NGO	Moderate	Moderate	Suitable in arid and semi-arid areas	Minimizes soil erosion	Good water quality Ease of operations and maintenance	Low level of services	Acceptable	Should be promoted for adaption
Fog harvesting	Rarely used	Low	Government	High capital investment	Limited	Suitable for areas with scarce water resources		Low operations and maintenance costs	Limited production	Acceptable	To be used where other technologies and limited
Ground water abstraction-Handpump equipped wells	Extensively used	Low	Community Government NGO	Low in capital and recurrent	High	Suitable where ground water is available within reasonable depth	Point sources can cause degradation of environment	Low costs Good quality water Ease of community management	Low level of services	Moderately acceptable	Should be promoted and community participation intensified
Rope washer pumps	Moderately used	Low	Community Government, NGOs	Low	Low	Shallow wells Surface water		Low costs	Limited use	Acceptable	To be adapted whenever feasible
Artificial Recharge	Low	Low	Government NGOs	High	Moderate	Regions lacking alternative water sources	Can cause water/aquifer pollution	Water conservation achieved	Need for abstraction systems to reuse it	Acceptable	To be used if other methods are not feasible
Well tank Borehole /well	Moderate	Low	Community Government NGOs	High capital and low recurrent	High	In areas with very deep water tables		Low in operation and maintenance	High capital costs	Acceptable	Should be adapted in regions where water is found in great depths

DOMESTIC WATER SUPPLY (WATER QUALITY UPGRADING)

Technology	Extent of use	O & M	Level of involvement	Costs	Effectiveness	Suitability	Environmental Implication	Advantages	Disadvantages	Cultural Acceptability	Comments and Recommen-dations
Denitrification of Groundwater	Low	Moderate	Community NGOs Community	Low in capital and recurrent	Moderate	In regions with high level of nitrate concentration		Low in operations and maintenance	High capital costs	Acceptable	Should be adapted in regions where water is found in shallow depth
Iron removal unit	Mali Burkina Faso	Low	Community Government NGOs	Moderate capital Low recurrent	High	In regions with high level of iron concentration in groundwater		Low costs Ease of maintenance Saving achieved on rehabilitation of pumps	None identified	Acceptable	To be promoted for adaption
Use of natural plants	Extensively used in West and Central Africa	Low	Community	Low	High	Surface water treatment		Low costs Good water quality	Seeds not available throughout the year	Acceptable	Should be promoted for adaption
In stream water quality upgrading	Ghana	Low	Community Government NGOs	Low capital and recurrent	Moderate	In rural areas with surface water		Low costs No chemical required Good quality water	Low level services Lifting mechanism required	Acceptable	To be adapted whenever possible

DOMESTIC WATER SUPPLY (WATER CONSERVATION)

Technology	Extent of use	O & M	Level of involvement	Costs	Effectiveness	Suitability	Environmental Implication	Advantages	Disadvantages	Cultural Acceptability	Comments and Recommenda-tions
Urban water conservation	High	High	Government Water supply agencies	High	High	Urban areas		Water is conserved Saving resources	High costs	Acceptable	Application should be intensified

DOMESTIC WATER SUPPLY (WASTEWATER TREATMENT AND REUSE)

Technology	Extent of use	O & M	Level of involvement	Costs	Effectiveness	Suitability	Environmental Implication	Advantages	Disadvantages	Cultural Acceptability	Comments and Recommenda-tions
Direct reuse of treated municipal wastewater	Low	High	Government Water supply agencies	High	Moderate	Areas with scarce water resources	Can cause health problems	Augmentation of water	High costs Possible health hazards	Low	To be considered for used in the absence of alternative sources of water
Indirect reuse
Regeneration water	Zimbabwe	Moderate	Government Farmers	High capital and moderate recurrent	Moderate	In regions with limited water resources		Augmentation of volume of water achieved	High costs Saline water	Acceptable	To be used in areas of scarce water resources

MINING AND INDUSTRY (WATER QUALITY UPGRADING)

Technology	Extent of use	O & M	Level of involvement	Costs	Effectiveness	Suitability	Advantages	Disadvantages	Cultural Acceptability	Comments and Recommen-dations	Environmental Impact
Electrodialysis	Mining operation in South Africa	Requires skilled labour, close monitoring	Established mining or industrial concerns	High investment and running	80% removal of salts	Industrial and mining	Effective method of removal of salts from brackish water Reduces corrosion Water is reused	Not suitable for small scale application High capital and operational costs Highly skilled manpower Further treatment of product required to make it portable	No cultural concern	Analysis was based on trial test report	Proper disposal of liquid and gaseous by products required

MINING AND INDUSTRY (WASTEWATER TREATMENT AND REUSE)

Technology	Extent of use	O & M	Level of involvement	Costs	Effectiveness	Suitability	Advantages	Disadvantages	Cultural Acceptability	Comments and Recommen-dations	Environmental Impact
Industrial water reuse	Eastern and Southern Africa	Industry specific	Skilled manpowerEnforcement of regulations	Industry specific	Significant reduction in water demand	Urban water conservation	Reduce water demand	Investment in technology	No cultural barriers	Requires guidelines for other countries and industries	Minimizes pollution
Water conservation-Recycled water used for blending freshwater	Brewery and bottling industry-Achimota, Ghana	Regular maintenance of mechanical system	Skilled manpower	High initial capital costs Reasonably low operating costs	Significant reduction in raw water demand	Industry that demands a lot of boiler water	Saving on water demands and industry Can be modified to include other sources of water such as groundwater	Only applicable where there are heat exchanges Impure water could result in scaling of boilers	No cultural barriers		No adverse environmental impact
Water recycling in Gold Mines	Underground gold mines Extensive application in Ghana	Pumps operate 10 hours a day Regular maintenance of pumps and reservoir required	trained personnel needed to manager pumping system Regular maintenance of pumps and reservoir	High capital and mining costs	Ensure adequate primary treatment of waste water from mining operations Ensure year round supply of water for mining operation	Applicable in subsurface mining systems	Limits pollution load on surface augmentation	Required fuel/energy for pumping Further treatment of reservoir water might be required to meet effluent standards	No cultural concerns	Technology specifically relevant to case at Tankwe Golden Mines in Ghana	Technology minimizes direct pollution of surface water Proper disposal of waste products is reservoir is required to minimize environmental pollution

MINING AND INDUSTRY (WASTEWATER TREATMENT AND REUSE)

Technology	Extent of use	O & M	Level of involvement	Costs	Effectiveness	Suitability	Advantages	Disadvantages	Cultural Acceptability	Comments and Recommen-dations	Environmental Impact
Dry cooling at power station	Available in South Africa	Skilled manpower	Power utilities	Integral part of costs and generating stations	Water consumption for cooling is less than 20% of west cooling draft towers	Suitable for areas prone to water shortage with utilizes thermal power stations for power	Power production not influenced by drought Station siting not limited by proximity to river	Higher capital costs Less efficient than wet cooled systems Requires higher quality of groundwater that wet cooled system	No cultural problems
Utilisation of seawater for cooling	South Africa	Skilled labour	Power facilities	High capital costs	Avoids use of freshwater resources	Coastline situations	Alternative freshwater uses	Limited applicability	No cultural problems		Localised marine impact

MINING AND INDUSTRY (WATER HARVESTING)

Technology	Extent of use	O & M	Level of involvement	Costs	Effectiveness	Suitability	Advantages	Disadvantages	Cultural Acceptability	Comments and Recommen-dations	Environmental Impact
Ground water harvesting	Widespread	Moderate	Industry managed	Moderate	Significant for African industries	Where piped supplies are erratic	On site water availability Cost effective	Uncontrolled pumping	No cultural problems

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