Ecological Function

Many people live in and around the Okavango Swamp region, using the swamp for agricultural purposes as well as recreationally. The indigenous peoples of the country live in close proximity to the swamp in order to benefit from the rich deposits of silt and nutrients carried down the Okavango River. They use the swamp for fishing, hunting, collecting wild plants, pastoralism, and mixed economies in agriculture.

There is also another aspect to using the swamp as a source of subsistence and survival. Many people who live in regions close to the swamp engage in tourism. Tourism is a growing sector of Botswanan livelihood. They are very knowledgeable about their country and are proud to share their knowledge with others. Sustainable tourism not only helps support the greater Botswanan economy, but allows others to become more knowledgeable about another part of the world and to help with conservation efforts--the last remaining vestiges of untouched land need to be conserved rather than thrown away because it's just easier.

The Okavango Swamp aids not only in the primary productivity of the system, but in flood control, erosion of the land, and supporting a huge diversity of flora and fauna. As the water surged from the Angolan Highlands, through Namibia and into the Okavango Swamp, it gathers larger amounts of nutrients and silt, and deposits them in the basin of the Okavango Swamp. The silt and nutrients carried by the Okavango River supports and diverse number of trees, grasses and flowering plants, as well and hundreds of species of birds, mammals, and reptiles. As the flood waters reach the Okavango Swamp, the productivity of the swamp kicks into over drive and the vegetation flourishes and the animal life returns to exploit the vegetative resources of the swamp.

Flood control of the Okavango River is aided by the sand-silt characteristic of the soil, as well as the intense vegetation cover. The soil has an intermediate porosity and permeability, with the water accumulating above the soils surface, with only a fraction penetrating into the groundwater. As the water levels rise in the Okavango Swamp, the Thamalakane River (a tributary leaving the swamp) discharges excess water into Lake Dow. And during extraordinary flood years, the Okavango Swamp sends a surplus of water to the Kwando River which, in turn, joins the Zambezi. If the Zambezi floods arise early, however, the process may be reversed. Most of the water loss from the Okavango Swamp, in late October/early November, is due to evaporation, with a small fraction leaching into the ground water.

The intense vegetative cover of the swamp also helps in prevent surface erosion of the soil as the water surged into the swamp from the high velocity Okavango River. The vegetation slows the flow of the river and allows the water to accumulate in the Okavango basin, enhancing not only the deposition of nutrients and silt, but aiding in increased vegetation growth and supporting a diverse range of wildlife. The swamp provides great wildlife habitat with both great food resources and great protection from predators. There is also high diversity in the type of wildlife that inhabits the swamp because there are both islands, shallow reed beds and lily ponds, and open water channels. By supporting a high diversity of wildlife, the productivity is enhanced by the nutrient input and cycling as they eat the vegetation and eliminate in the swamp. The nutrient cycling follows the same cycle as the flood waters--thus is the dry season, nutrients are more scarce; while during the flood season, nutrients are abundant and replenished frequently. Thus, without the Okavango Swamp, there would be intense floods, no nutrient traps, and thus the diversity of wildlife would be greatly diminished.

The widllife follows the flood patterns of the swamp. As the waters surge into the swamp in late May/early June, thw widllife is drawn back into the swamp by the tempting vegetation and abundant food supply. But, when the waters receed in late October/early November, the animals follow the water. During the dry season, the animals move into the northern regions of the swamp, where the water is more permanent and the resources are more predictable. These seasonal migrations are more influenced by the water levels rather than the need to just move from one place to the next--this is the same type of animal migrations that take place all over the African continent.