A dambo is a class of complex shallow wetlands in central, southern and eastern Africa, particularly in Zambia and Zimbabwe. They are generally found in higher rainfall flat plateau areas, and have river-like branching forms which in themselves are not very large, but combined add up to a large area. Dambos have been estimated to comprise 12.5% of the area of Zambia. Similar African words include mbuga, matoro, vlei, fadama, and bolis ; the French bas-fond and German Spültal have also been suggested as referring to similar grassy wetlands.
Characteristics of dambos
Dambos are characterised by grasses, rushes and sedges, contrasting with surrounding woodland such as Miombo woodland. They may be substantially dry at the end of the dry season, revealing grey soils or black clays, but unlike a flooded grassland, they retain wet lines of drainage through the dry season. They are inundated in the wet season but not generally above the height of the vegetation and any open watersurface is usually confined to streams, rivers and small ponds or lagoons at the lowest point, generally near the centre. The name dambo is most frequently used for wetlands on flat plateau which form the headwaters of streams and rivers. The definition for scientific purposes has been proposed as “seasonally waterlogged, predominantly grass covered, depressions bordering headwater drainage lines”.
Types of dambo
The problem with the preceding definition is that the word may also be used for wetlands bordering rivers far from the headwaters, for example the dambo of the Mbereshi River where it enters the swamps of the Luapula River in Zambia,. A 1998 report of the FAO distinguished between ‘hydromorphic/phreatic’ dambos and ‘fluvial’ dambos, and also referred to five geomorphological types in Zambia’s Luapula Province: upland, valley, hanging, sand dune and pan dambos.
Hydrology of dambos
Dambos are fed by rainfall which drains out slowly to feed streams and rivers, and are therefore a vital part of the water cycle. As well as being complex ecosystems in themselves they also play a role in the biodiversity of the region. There is a popular idea that dambos act like sponges to soak up the wet season rain which they release slowly into rivers during the dry season thus ensuring a year-round flow, but this is opposed by some research which suggests that in the middle to late dry season the water is actually released from aquifers. Springs are seen in some dambos. What this means in practice is that it may take a long time, perhaps several years, for water from a heavy rainy season to percolate through hills and emerge in a dambo, creating lagoons there or a flow in downstream rivers which can't be explained by the previous year's rainfall. Dambos may be involved, for instance, in explaining puzzling variations in water level or flow in Lake Mweru Wantipa and Lake Chila in Mbala.
for growing vegetables and other food crops, which can be vital in drought years since dambo soils usually retain enough moisture to produce a harvest when the rains fail
for fishing in those dambos with streams and rivers
More recently, they have been used for fish ponds and growing upland rice. Efforts to develop dambos agriculturally have been hampered by a lack of research on the hydrology and soils of dambos, which have proved to be variable and complex.
Example
A good example of a dambo can be seen at in a forest reserve. Unlike in the neighbouring areas which have been cleared for farming and charcoal-burning, the dambo contrasts well with the undisturbed Miombo woodland canopy. Headwater dambos have a branching structure like rivers. Most of the dambos have roughly the same width and form the same sort of pattern. An example of a pan dambo can be seen at . The water in the pan has dried out and the grass has been burnt off giving the dark appearance at the centre of the dambo. To the east and west of the pan dambo a series of dambos can be seen along two river courses.
