Adambo is a class of complex shallowwetlands in central, southern and eastern Africa, particularly inZambia,Malawi andZimbabwe. 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.[1] Similar African words includembuga (commonly used inEast Africa),matoro (Mashonaland),vlei (South Africa),fadama (Nigeria), andbolis (Sierra Leone); the Frenchbas-fond and GermanSpültal have also been suggested as referring to similar grassy wetlands.[2]
Dambos are characterised by grasses, rushes and sedges, contrasting with surrounding woodland such asmiombo woodland. They may be substantially dry at the end of the (dry season), revealing grey soils or black clays, but unlike aflooded grassland, they retain wet lines of drainage through the dry season. They are inundated (waterlogged) in the (wet season) but not generally above the height of the vegetation, and any open water surface is usually confined to streams and small ponds or lagoons (small swamps) at the lowest point generally near the centre.
The name dambo is most frequently used for wetlands on flat plateaus which form theheadwaters of streams. The definition for scientific purposes has been proposed as "seasonally waterlogged, predominantly grass covered, depressions bordering headwater drainage lines".[3]
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 theMbereshi River where it enters theswamps of theLuapula River in Zambia,09°43′30″S28°46′00″E / 9.72500°S 28.76667°E /-9.72500; 28.76667.
A 1998 report of theFood and Agriculture Organization distinguishes between 'hydromorphic/phreatic' dambos (associated with headwaters) and 'fluvial' dambos (associated with rivers), and also referred to five geomorphological types in Zambia'sLuapula Province:upland,valley,hanging,sand dune andpan dambos.[4]
Dambos are fed by rainfall which drains out slowly to feed streams and are therefore a vital part of thewater cycle. As well as being complex ecosystems, they also play a role in thebiodiversity of the region.[4]
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 fromaquifers.[5]Springs are seen in some dambos. Thus 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 cannot be explained by the previous year's rainfall. Dambos may be involved, for instance, in explaining puzzling variations in water level or flow inLake Mweru Wantipa and Lake Chila inMbala.
Traditionally, dambos have been exploited:
More recently, they have been used forfish ponds and growing uplandrice. 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.[4]
A dambo can be seen at11°28′S28°54′E / 11.467°S 28.900°E /-11.467; 28.900 (30 km south ofMansa, Zambia) in a forest reserve. Unlike in the neighbouring areas which have been cleared for farming and charcoal-burning, the dambo contrasts well with the undisturbedmiombo 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 at16°22.003′S24°18.580′E / 16.366717°S 24.309667°E /-16.366717; 24.309667 (102 km north-west ofMulobezi, Zambia). 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.
