is a word used for a class of complex shallow wetlands in central, southern and eastern Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, particularly in Zambia
Zambia , officially the Republic of Zambia, is a landlocked country in Southern Africa. The neighbouring countries are the Democratic Republic of the Congo to the north, Tanzania to the north-east, Malawi to the east, Mozambique, Zimbabwe, Botswana and Namibia to the south, and Angola to the west....
Zimbabwe is a landlocked country located in the southern part of the African continent, between the Zambezi and Limpopo rivers. It is bordered by South Africa to the south, Botswana to the southwest, Zambia and a tip of Namibia to the northwest and Mozambique to the east. Zimbabwe has three...
. They are generally found in higher rainfall flat plateau areas, and have river-like branching forms which may be nowhere very large, but common enough to add up to a large area. For instance, dambos have been estimated to comprise 12.5% of the area of Zambia. Similar African words include mbuga
(commonly used in East Africa), matoro
(South Africa), fadama
(Nigeria), and bolis
(Sierra Leone); the French bas-fond
and German Spültäl
have also been suggested as referring to similar grassy wetlands.
Characteristics of dambos
are characterised by grasses
The Poaceae is a large and nearly ubiquitous family of flowering plants. Members of this family are commonly called grasses, although the term "grass" is also applied to plants that are not in the Poaceae lineage, including the rushes and sedges...
Juncus is a genus in the plant family Juncaceae. It consists of some 200 to 300 or more species of grassy plants commonly called rushes...
and sedges, contrasting with surrounding woodland such as Miombo woodland
Miombo is the Swahili word for Brachystegia, a genus of tree comprising a large number of species. Miombo woodland is classified in the tropical and subtropical grasslands, savannas, and shrublands biome...
. 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 (waterlogged) in the wet season but not generally above the height of the vegetation and any open water surface is usually confined to streams, rivers and small ponds or lagoons at the lowest point, generally near the center.
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
The Mbereshi River drains the northern Zambian plateau north of Kawambwa and flows west into the Luapula valley. It enters the Luapula swamps near the Mofwe Lagoon. It gives its name to the village and former mission of Mbereshi situated near its south bank....
where it enters the swamps of the Luapula River
The Luapula River is a section of Africa's second-longest river, the Congo. It is a transnational river forming for nearly all its length part of the border between Zambia and the DR Congo...
in Zambia, 09°43′30"S 28°46′00"E.
A 1998 report of the FAO distinguished between ‘hydromorphic/phreatic’ dambos (associated with headwaters) and ‘fluvial’ dambos (associated with rivers), and also referred to five geomorphological types in Zambia’s Luapula Province
Luapula Province is one of Zambia's nine provinces, and is located in the north of the country. The provincial capital is Mansa. Luapula Province was named after the Luapula River....
, sand dune
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
The water cycle, also known as the hydrologic cycle or H2O cycle, describes the continuous movement of water on, above and below the surface of the Earth. Water can change states among liquid, vapor, and solid at various places in the water cycle...
. As well as being complex ecosystems in themselves they also play a role in the biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
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
A spring—also known as a rising or resurgence—is a component of the hydrosphere. Specifically, it is any natural situation where water flows to the surface of the earth from underground...
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
Lake Mweru Wantipa is a lake and swamp system in the Northern Province of Zambia. It has been regarded in the past as something of mystery, displaying fluctuations in water level and salinity which were not entirely explained by variation in rainfall levels; it has been known to dry out almost...
and Lake Chila in Mbala
Mbala is Zambia’s most northerly large town and seat of Mbala District, occupying a strategic location close to the border with Tanzania and controlling the southern approaches to Lake Tanganyika, 40 km by road to the north-east, where the port of Mpulungu is located. It had a population of about...
Use of dambos
, dambos have been exploited:
- as a dry-season water source
- for rushes used as thatching
Thatching is the craft of building a roof with dry vegetation such as straw, water reed, sedge , rushes, or heather, layering the vegetation so as to shed water away from the inner roof. It is a very old roofing method and has been used in both tropical and temperate climates...
and fencing material
- for clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
used for building, brick-making and earthenware
Earthenware is a common ceramic material, which is used extensively for pottery tableware and decorative objects.-Types of earthenware:Although body formulations vary between countries and even between individual makers, a generic composition is 25% ball clay, 28% kaolin, 32% quartz, and 15%...
- for hunting (especially birds and small antelope
Antelope is a term referring to many even-toed ungulate species indigenous to various regions in Africa and Eurasia. Antelopes comprise a miscellaneous group within the family Bovidae, encompassing those old-world species that are neither cattle, sheep, buffalo, bison, nor goats...
- 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 soaking bitter cassava
Cassava , also called yuca or manioc, a woody shrub of the Euphorbiaceae native to South America, is extensively cultivated as an annual crop in tropical and subtropical regions for its edible starchy tuberous root, a major source of carbohydrates...
in dug ponds
- for fishing
Fishing is the activity of trying to catch wild fish. Fish are normally caught in the wild. Techniques for catching fish include hand gathering, spearing, netting, angling and trapping....
(generally using fish traps) in those dambos with streams and rivers
, they have been used for fish ponds
Fish farming is the principal form of aquaculture, while other methods may fall under mariculture. Fish farming involves raising fish commercially in tanks or enclosures, usually for food. A facility that releases young fish into the wild for recreational fishing or to supplement a species'...
and growing upland rice
Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...
. 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.
A good example of a dambo can be seen at 11°28′S 28°54′E (30 km south of Mansa
Mansa is a Mandinka word meaning "king of kings". It is particularly associated with the Keita Dynasty of the Mali Empire, which dominated West Africa from the thirteenth to the fifthteenth century...
, 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 undisturbed Miombo woodland canopy. Note also that headwater dambos have a branching structure like rivers. Most of the dambos have roughly the same width and form the same sort of pattern.