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Okavango Delta

Date of Submission: 27/05/2010
Category: Natural
Submitted by:
Department of National Museum and Monuments
State, Province or Region:
Ngamiland
Coordinates: 19 17S 22 54E
Ref.: 5554
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Description

 Okavango Delta System is located in the northwestern part of Botswana linked by a major channel of Okavango River (forming the panhandle) that originates in the Angolan highlands as two rivers of Cubango and Cuito that confluence into a broad channel flowing through Namibia into Botswana. Three main features characterize the region; the Okavango, the Kwando and Linyanti River system connected to the Okavango Delta through the Selinda spillway and the intervening surrounding dry land areas. The Delta has developed in a depression in the Kalahari bedrock covering approximately 6000 km of permanent swamps with seasonal variation of swamps between 4000 and 10 000km2 in size. The annual inflow ranges between 7000 and 15 000 million cubic meters of which 97% is lost to evapotranspiration and seepage leaving only 3% to exit past Maun through the Thamalakane River, about 500km from the panhandle. This is a pristine inland Delta measuring over 16,000 km2 in size which supports the lives of over 120 000 people by providing freshwater, food, building materials, medicinal plants as well as employment through a viable tourist industry.

The Delta is situated in a semi-arid region with rainfall (in Maun) ranging from 195 and 940 mm per  annum with summer months (November to March) recording an average of 455mm in Maun and 480mm over the Delta. The rainfall is highly variable with a coefficient of variation of annual rainfall of 35% which is characteristic of an arid environment. The monthly mean temperature ranges from 16-26oC in June (winter) and October (summer) respectively.

The Okavango Delta is a wetland in an otherwise arid environment that is an extension of Botswana's Kalahari Desert and incorporates a variety of habitats including woodlands, riverine forests grasslands, floodplains and sand veldt islands. Most vegetation in flooded areas consists of sedges, grasses and aquatic plants. Woody species are restricted to the dry land areas and islands, with the exception of water fig. The maximum flooding occurs in the winter (dry) months and thus provides important dry season forage and water for wildlife. Dry land areas form important grazing areas in the rainy season. Fluctuations in flooded areas are very important for productivity, both primary and secondary. Permanent and seasonal floodplains form critical habitat for many species of wildlife and birdlife that are at their southern limits of distribution in the region.

 The Delta supports an outstanding biodiversity of life including 150 species of mammals, over 500 species of birds, 90 species of fish, as well as plants, reptiles, invertebrates and amphibians. The Moremi Game Reserve is a part of the Delta System and in this area all wildlife is protected. This game reserve is unique in that it was founded by the local tribe. Outside the game reserve and the Wildlife Management Areas is communal land where subsistence farming and livestock farming are the common forms of land use. Fishing for subsistence also takes place.

Justification of Outstanding Universal Value

 The Okavango Delta is a vast freshwater inland Delta situated within the extensive dry Kalahari Desert woodland region, biologically rich and vital to sustaining the ecosystem services that support all life present in the area.  Okavango Delta is the largest inland delta in the world (16 000km2) and displays an expansive landscape with superlative natural scenic beauty. It has a dramatic geological and hydrological history. The Delta overlies solid basement bedrock which is aligned into two trends of NW-SE (older) and NE-SW (younger). Tectonic movement of the younger formation has caused a down faulted depression to form. The depression captured the Kavango River from the Zambezi River. This depression is an extension of the East African Rift System with currently active Faults (Thamalakane, Kunyere and Gumare) that have influenced the flow of the waters and associated biodiversity. The Delta System is one of the most diverse ecosystems in sub Saharan Africa in terms of wetland and dryland natural habitats supporting a large, diverse terrestrial and aquatic biota within a wide range of ecological niches.

Criteria

 The Okavango Delta System fulfills criteria vii, viii, ix and x for natural sites.

vii.          contain superlative natural phenomena or areas of exceptional natural beauty and aesthetic importance;

Okavango Delta is a natural feature of great aesthetic importance in the sense that the numerous channels transformed the otherwise dry desert environment into scenic landscape with permanent crystal clear waters and associated islands resulting in outstanding natural scenic beauty which is even more pronounced by the fact that flooding takes place during drier winter season. This outstanding beauty which is particularly more appreciated from air attracts thousands of tourists from abroad annually.

viii.      be outstanding examples representing major stages of earth's history, including the record of life, significant on-going geological processes in the development of landforms, or significant geomorphic or physiographic features;

Okavango Delta is an inland alluvial fan within southern terminus of the East African Rift Valley system extension with currently active faults that have influenced the flow of the waters and associated biodiversity. The dynamics of the flow regimes of the Delta are highly controlled by the ongoing geological tectonic movement than the normal sediment deposition load. The Okavango Delta overlies solid basement bedrocks which are aligned into two trends of NW-SE (older) and NE-SW (younger). Tectonic movement of the younger formation has caused a down faulted depression to form. The depression captured the Kavango River from the Zambezi River to form this major inland Delta in the otherwise dry Kalahari Desert landscape dominated by stabilized linear sand dunes. The continuous transformation of geomorphic features such as islands, channels, river banks, flood plains, oxbow lakes and lagoons significantly influence the dynamics of ecological habitats  of the Delta.

ix.           be outstanding examples representing significant on-going ecological and biological processes in the evolution and development of terrestrial, fresh water, coastal and marine ecosystems and communities of plants and animals;

The Okavango Delta is an outstanding example of interplay between the geological, geomorphological and hydrological processes that drive the ecological and biological processes in the development of terrestrial and freshwater ecosystems and communities of plants and animals. The Delta supports an outstanding biodiversity including 150 species of mammals, over 500 species of birds, 90 species of fish, as well as plants, reptiles, invertebrates and amphibians. Okavango Delta is a magnet of ecological establishment of the area which has resulted in unique food chain/web interrelations of a complex nature whereby all major animal classes are adequately represented from both land and aquatic species. Since the delta floods during dry winter season when water is critically needed in the area, most animals converge in the delta and an interesting interaction is set up.

In the Delta there are large variations in habitat patterns over small distances, although the Delta is very flat and is made up of homogeneous sand. Small differences in altitude of 1-2m result in large differences in the frequency and duration of flooding, which creates habitat gradients from permanent rivers and lagoons, to permanent swamps with reed and papyrus, seasonally flooded grasslands, occasionally flooded grasslands, and riverine woodlands and dry woodlands. Each of these habitats has a distinct species composition of plants and animals comprising all the major classes of reptiles, birds and mammals.

 x.            contain the most important and significant natural habitats for in-situ conservation of biological diversity, including those containing threatened species of outstanding universal value from the point of view of science or conservation.

In the Delta there are large variations in habitat patterns over small distances, although the Delta is very flat and is made up of homogeneous sand. Small differences in altitude of 1-2m result in large differences in the frequency and duration of flooding, which creates habitat gradients from permanent rivers and lagoons, to permanent swamps with reed and papyrus, seasonally flooded grasslands, occasionally flooded grasslands, and riverine woodlands and dry woodlands. Each of these habitats has a distinct species composition of plants and animals comprising all the major classes of reptiles, birds and mammals.

The existing Moremi Game Reserve within the Okavango Delta has some of the highest animal species populations in southern Africa that is comparable with the rich savannas in the East African Rift Valley. Okavango Delta supports globally threatened and endangered species of both plants and animals. Such animal species include wild dogs, cheetahs, lions, black and white rhinos, Red lechwe and sitatunga antelopes. The Delta provides habitat for aquatic species such as hippopotamus, sitatunga and Red lechwe which fall under the IUCN Red List. There are about 444 confirmed bird species occurring in the Okavango Delta of which 8 are globally threatened and near threatened. Furthermore, Okavango Delta is a habitat to 1061 plant species of which 20 have been selected for the Red List Status using the IUCN Red list criteria.

Statements of authenticity and/or integrity

 Integrity

Okavango Delta is a massive physiographic feature that covers 16 000 km2 of land with a wide range of natural features that have only been undergoing geological processes. The area therefore, accommodates all the natural processes encompassing the geomorphic, hydrogeological and biological components. There is little transformation still operating in near natural aspects of the environment. There are no manmade dams and major hydrological infrastructural developments such as canals and water abstraction. However, the only developments that have taken place are limited tourism activities being negligible of the total proposed area.

 The Moremi Game Reserve which covers an area of 4 865km2 was initially set up by the local community as a protection area before the country's independence. The Government later took over and committed itself to the Management of the Reserve.  The Government further established Wildlife Management Areas and Community Hunting Areas in an effort to involve local communities in sustainable utilization and conservation of the natural resources of the area. In the Game Reserve only non-consumptive activities takes place. The Reserve therefore has remained in its wilderness with very little human interference providing total protection of the wildlife and natural vegetation. Controlled Hunting Areas (CHAs) and Wildlife Management Areas (WMAs) provide control to the use of natural resources in the Delta especially the wildlife.

 The Management Authority of the proposed site is the Ministry of Environment, Wildlife and Tourism which comprises all departments relevant for the management of the Delta.  Land use in the buffer zone is strictly controlled by the Tawana Land Board which is the land authority representing the government. The control of land use in the area provides the necessary protection of natural resources in the area. Furthermore and most importantly the Okavango Delta as a Ramsar site enjoys the highest levels of conservation as per the Ramsar convention clearly defined and gazette boundaries. The Okavango Delta Management Plan also provide protection as it encourages wise use of resources in the area and provide strategic goals and objectives needed to manage the area effectively.

 There are adequate laws, policies and regulations in place that the Botswana Government is administering for the protection of the Okavango Delta. These include Environmental Impact Assessment Act of 2005, Wildlife Conservation and National Parks Act of 1992, Monuments and Relics Act of 2001, Forest Act of 1976 and Water Act of 1968.  Botswana is a signatory to some crucial international conventions that include RAMSAR, Convention on Biological Diversity(CBD), Convention on International Trade on Endangered Species of Wild Fauna and Flora (CITES)  and World Heritage as well as regional treaties that include the Permanent Okavango River Basin Commission (OKACOM) and Southern African Development Community (SADC) Shared Watercourse Systems Protocol. These two regional agreements are critical for the protection of the source point and panhandle of the Delta System

Comparison with other similar properties

 In a world-wide biodiversity comparison of seven globally important wetlands, of which 6 are located in tropics and sub-tropics, the Okavango has the highest number of reptiles and bird species, second highest number of plant and mammal species, and third highest number of fish species (Junk et al, 2006). The existing Moremi Game Reserve within the Okavango Delta has some of the highest different animal species populations in southern Africa that is comparable with the rich savannas in the East African Rift Valley