Newsletter and Technical Publications
<Sourcebook of Alternative Technologies for Freshwater Augumentation
1.4.3 Savanna Wetland Cultivation
This technique involves the cultivation of valley wetlands found in the
plateau savanna regions of Africa (called dambos in southern Africa;
Figure 24). Dambos are a multipurpose land and water resource being
used for water supply, grazing and cultivation. Dambo catchments
were thought to act as hydrological reservoirs, storing water in the rainy
season and releasing it through evapotranspiration from the dambo surface
and dry season stream flow. This was used as a basis for legislative
protection of wetland but has not been supported by more recent
hydrological investigations (Owen et al., 1995).
Figure 24. Dambo distribution in southern Africa (Bell
et al., 1987).
Erosion plot and gully monitoring studies suggest that garden
cultivation does not appreciably increase soil losses from dambos.
Figure 25. Dambo land use recommendations (Bell et
This technology may be called micro-scale irrigation and involves the
utilisation of water around the periphery of a wetland using conventional
agricultural methods (Figure 25).
Garden cultivation appears best suited to the upper wet zone of the dambo
and should not normally exceed 10% of the total catchment area.
Extent of Use
Dambos are used for small- scale cultivation on farms ranging in area
from 15 to 20 000 ha in Zimbabwe. Discouraged by colonial legislation, they have
been developed entirely through local initiatives.
Operation and Maintenance
Depending upon the season, raised beds may be necessary to protect crops from
Level of Involvement
This technology is entirely farmer-initiated and managed.
There are no additional costs relative to conventional cultivation techniques
incurred through the use of this technology.
Effectiveness of the Technology
Studies have shown that the upper dambo zone, which normally remains
wet throughout the year, offers an insurance against years when rain-fed crops
fail. Gardens on dambos provide food security through the production of
staple crops, dietary variety through the production of vegetables, and also
cash income to farmers and their families.
This technology is suitable for shallow, seasonally-waterlogged depressions
at the head of a drainage network. Such depressions are quite common and
therefore this method is suitable for increasing crop production in these areas.
Experiments carried out jointly by the University of Loughborough and the
University of Zimbabwe have shown that there are no adverse environmental
The small size of dambos (0.1 to 1 km wide by 0.5 to 5 km long)
suggests that a small-scale approach is most suitable. It provide food security
in years of poor rain-fed agricultural production and allows some dry season
Perceptions of environmental risk, which have not been dispelled by the
limited data available, remain.
The practice has been developed by local people, who have no cultural
problems with it.
Further Development of the Technology
There is a potential for considerable expansion of wetland cultivation in
Africa which will probably require a clarification of the policy situation and
removal of restrictive legislation. The impact on the environment should be
Bell, M., R. Faulkner, P. Hotchkiss, R. Lambert, N. Roberts, and A. Windram
1987. The Use of Dambos in Rural Development, with Reference to Zimbabwe.
Loughborough University, University of Zimbabwe.
Owen, R., K. Verbeek, J. Jackson, and T. Steenhuis (Editors) 1995. Dambo Farming
in Zimbabwe: Water Management, Cropping and Soil Potentials for Smallholder
Farming in Wetlands. Conference Proceedings. University of Zimbabwe, CIIFAD