Given the conditions of unpredictable rainfall, and very high evaporation losses, the Zambezi Basin is generally poor in water resources.

Although several public water institutions and agencies are doing their best to save and use water efficiently, there are many examples of inefficiency, unfairness in allocation and unsustainability in the use and management of water resources which make it very difficult to satisfy the growing demand for safe water supplies.

Regional estimates put renewable freshwater resources at an annual average of 650 million cubic metres, distributed in the basin's rivers, lakes and groundwater. Rainfall is the main source of water, and is critical to the success of agriculture and industry and to the survival of people, plants and wildlife.

Freshwater resources
Rainfall
There are variations in the amount of rain and its onset and intensity during the wet season. The pattern of rainfall in the basin is influenced mainly by three major factors: ocean currents, global air circulation and topography.

The Zambezi Basin is characterised by low to fairly good rainfall. Droughts are frequent and can occur more often. Rainfall is variable in terms of the total amount received as well as in its duration during the season, and these factors tend to vary even more in arid areas.

Source: J. Pallet, Sharing Water in Southern Africa
Surface waters
Wetlands, together with rivers and lakes, are the major sources of water and are rich areas in terms of the numbers and diversity of plants and animals. Almost 13 percent of the basin is made up of freshwater wetlands which can be divided into four main types. These are natural and artificial lakes, rivers, dams and palustrine areas (swamps, marshes and dambos).

There are a number of internationally known marshes in the basin, such as Kafue flats. The Barotse and Kafue in Zambia hold enough water during the rainy season to sustain economic activities such as inland fisheries and the Elephant marshes of Malawi are important for fish-spawning.

Natural and artificial lakes
There are three large artificial lakes in the basin, Kariba, Cahora Bassa and Kafue Gorge. These are primarily intended for hydropower generation. However there are many other medium size dams and thousands of small ones used for urban and rural water supply, livestock watering and irrigation.

Lake Malawi/Nyasa, Africa's third largest, is the only natural lake within the Zambezi Basin. While rivers can be used to feed reservoirs, lakes are useful water sources to those within their vicinity. The natural and artificial lakes of the basin require funds to develop as water sources to meet future needs.

Groundwater
Groundwater is the main source of water for many rural people throughout the Zambezi Basin, catering for about 80 percent of the human and animal populations in Botswana and at least 50 percent in Namibia. Malawi has more than 10,000, Tanzania more than 4,000 and Zimbabwe about 35,000 boreholes.

The demand for groundwater in the basin is increasing and will continue to increase, as will demand for water from all sources. Among water managers there is a general feeling that data on groundwater is insufficient and record-keeping inadequate. Supplies and their quality are not really known except in specific cases, levels of usage are only estimates, recharge rates are partially known and processes are debated.

Water availability and distribution
Across the basin, the year is divided into a dry season without rain and a wet season when rain may occur. The length of the wet season varies from a few weeks to seven months. The distribution, occurrence and availability of water resources are uneven in the basin as well as in individual countries.

Developments that impact on water resources are population growth, economic development, land-use patterns and climate change at basin and national levels. As the basin population is estimated to rise, from present 31.7 million to about 70 million by 2025, there will be less and less water available per person.

The natural environment can supply only a certain amount, and if demand exceeds that limit, social unrest can be expected. For example, in Zambia population growth has placed heavy demands on wetland resources such as fish, resulting in overexploitation in some wetland areas such as Kafue flats.

Water demand
Increasing water demand is a crucial concern in the Zambezi Basin and the southern African region at large. This is owing to increasing human population and associated demand for resources, especially food. The demand for water is for both consumptive and non-consumptive uses.

Consumptive use occurs when water is removed from its source and supplied for a specific purpose such as domestic needs, agriculture and industry. Non-consumptive use is when water is utilised without taking it out of the water body or returned there if it is. Hence it can be re-used and is not lost. Hydropower generation is an example of non-consumptive use of water.

Seasonal variations and unreliability of rainfall make irrigation important in the basin. Irrigation is of particular concern when considering the region's future planning. It accounts for almost three-quarters of all water used and of this amount, about 60 percent of the water is wasted.

A total of eleven hydropower plants with a total installed capacity of 4,620 MW and an average annual generation of some 33 TWh have been developed in the Zambezi Basin. Of the installed capacity about 5 percent is in Malawi, 45 percent in Mozambique, 36 percent in Zambia and 14 percent in Zimbabwe.

About 75 percent of the installed capacity is on the Zambezi River itself. The demand for electricity is certain to increase with population and economic growth, which will increase the development of more hydroelectric power and exert additional pressures or demands on the resource.

- Means unavailable

Source: P. Heyns, for SARDC, 1995

* This total does not include water demand for nature

Management of water resources
Water resources have always been central to human life and as such water has been described as the single most important resource for our future and the pivot on which all future development depends. There is not enough water to satisfy everyone's needs and this makes it necessary to manage or control the demand for it.

Water resources management affects and is affected by all other forms of land use such as agriculture, industry and environmental needs and therefore must take place at levels where interaction between these sectors can occur easily.

Rural communities, poor peri-urban dwellers and people in fringe areas often come up with their own solutions for water supply. For example there are ways of harnessing surface and rainwater with roof catchments, ponds, small dams and locating promising spots for groundwater. Such efforts require commitment, a few days' labour and ongoing maintenance among other resources.

However the biggest challenge would be to provide incentives for communities to undertake self-help projects that direct the people towards safe and sustainable exploitation of the resource.

In cases where water demand grows beyond what is immediately accessible, management should deal with competition between various interests and allocate set amounts to such interests.

Setting priorities for certain uses of water must be coordinated across the length and breath of a river basin.

Land and water uses, rural and urban interests and upstream and downstream areas should be integrated with the help of formal institutions. All affected parties should jointly and responsibly decide on the allocation of water throughout the basin.

At national level management, central government and its agencies should have the responsibility to decide on basic principles of water resources by:

1. Setting policy for water use in the country.
2. Assuming regulatory and controlling function of deciding on standards,         control and combat pollution and ensure environmental sustainability of                any developments.
3. Providing technical, administrative, financial and legal services.
4. Addressing social functions of water, guaranteeing that nobody is denied a lifeline quantity of water because of their socio-economic position.
5. Coordinating various sectors of the economy to ensure realism of development plans in terms of water demand.

While competition over water exists within and between countries in the basin, mechanisms such as the Zambezi River Action Plan (ZACPLAN) and the protocol on Shared Watercourse system in the Southern African Development Community (SADC) are in place to better manage water resources and minimise conflicts.

Technical water management measures should consider storage of surface or groundwater, aquifer recharge, water desalination, water recycling, reduction in wastage and water pollution control. The economic measures of pricing policies that control and limit wastage or control pollution and incentives such as tax exemptions to promote rational water use are also recommended.

Institutional measures take into consideration existing administrative institutions and capacity, available water resources, service delivery programmes and future systems needed to safeguard the quantities and quality of water without harming the environment.

The main task of water management is to cope with the conditions of water availability set by the environment, while satisfying people's needs and safeguarding the functioning of ecosystems, now and in the future.

Water resources management has, in the past, concentrated heavily on the technical side of supplying water, that is importing and exporting water, without balancing the environmental, economic and political aspects of water management. Managing water resources should take place at the lowest appropriate levels, that is at the levels where the constraints and needs are being encountered in society. In several countries this is now considered to be at catchment or sub-catchment level.

In all the riparian countries' rural societies, women are the main providers and users of household water. Rural women fetch and supply drinking water for their families and are heavily dependent on rain-fed agriculture.

Unless women are fully involved in discussing the problems and in deciding solutions, little success can be expected. Water programmes may fail or work ineffectively because of poor recognition of women's abilities.

Conclusion
Water consumption by the different countries in the basin is expected to increase especially with population growth, expanding industrialisation, agriculture and urban settlements. A basin-wide approach towards water management is necessary in order for countries to appreciate the implications of water management activities within their borders and at the regional scale.

Water is a finite resource and its effective management requires an integrated approach that takes into account various uses and environmental aspects of water resources and their utilisation.

Cost-effective integrated water management depends on a proper understanding of the multidisciplinary nature of water resources and a willingness to balance aspirations against practicalities.

Glossary

Arid means dry. An area with an arid climate has little precipitation.
Climate is the type of weather that is particular to a region or area seen from a long term perspective.
Climate change means any departure of weather conditions in region or area from its normal climate.
Evaporation is the process by which a solid or a liquid turn into vapour; loss of moisture as vapours.
Rainfall variability is the pattern of rainfall in arid environments when the amount of rain and where it falls differs widely from year to year.
Topography is natural features on the surface of the earth.

Sources

Direccao Nacional di Aguas    Rua Rainha, Ginga No. 210  
10 Andar, Luanda    
Angola   
Tel: 244-2-390 385  
Fax: 244-2-397 979   
       

Arquivo do Patrimonio Cultural e Juventude   
Caixa Postal 2702    
Rua do Bagamoyo No. 201, Maputo   
Mozambique   
Tel: 258-1-431366   
Fax: 258-1-429700   
       
   
Ministry of Energy and Water Development   
P.O Box 50288    
Lusaka Ridgeway 15101   
Zambia   
Tel: 260-1-252 011  
Fax: 260-1-252 589    

Department of Water Affairs   
P. Bag 0029
Gaborone 
Botswana   
Tel: 267-352 241  
Fax: 267-374 372    

Department of Water Affairs    
P. Bag 13193    
Windhoek   
Namibia  
Tel: 264-61-208 7111
Fax: 264-61-208 7227   

Ministry of Construction and Water   
ARA Sul Regional Water Authority    
P.O. Box 4033 Maputo  
Mozambique   
Tel: 258-1-431055/7 
Fax: 258-1-431058    

Ministry of and Water Development   
Department of Hydrology   
P. Bag 390, Lilongwe 3  
Malawi   
Tel: 265-780 344
Fax: 265-784 678    

Ministry of Water, Energy and Minerals  
Department of Environment   
P.O. Box 2000, Dar es Salaam   
Tanzania  
Tel: 255-51-314 33/5  
Fax: 255-51-371 39   

Ministry of Rural Resources and Water Development   
P. Bag 7712   
Causeway Harare 
Zimbabwe  
Tel: 263-4-704 119/707 861
Fax: 263-4-722 752   

    Bibligraphy

Chenje M., Johnson P. (eds.). 1996, Water in southern Africa, SADC/IUCN/SARDC, Maseru, Harare.
Pallet J., 1997. Sharing Water in southern Africa, Windhoek.

Dalal-Clayton B., 1997. Southern Africa Beyond the Millennium: Environmental Trends and Scenarios to 2015, International Institute for Environmental and Development, March, London.

SARDC-IMERCSA, 1997. State of the Environment Reporting Programme in the Zambezi Basin Project Document, November, Harare.

Mubvami T., 1998. Population and Settlement in the Zambezi Basin (unpublished paper), Harare.