The Okavango Delta comprises permanent marshlands and seasonally flooded plains in the northwest of Botswana. It is a rare wetland in that it is a major interior delta system that does not flow to the sea and has the unique characteristic of annual flooding during the dry season. The Delta functions as a fluvial lifeline to the myriad of species that inhabit the region, and the area is an exceptional example of the interaction between climatic, hydrological and biological processes. Furthermore, the Delta supports multiple iconic species such as the African Elephant as well as threatened species such as the African Wild Dog, Lion, Cheetah and Black Rhinoceros.
NATURAL WORLD HERITAGE SITE
2014: Inscribed on the World Heritage List under Natural Criteria vii, ix and x
STATEMENT OF OUTSTANDING UNIVERSAL VALUE
The UNESCO World Heritage Committee adopted the following Statement of Outstanding Universal Value at the time of inscription:
The Okavango Delta is a large low gradient alluvial fan or ‘Inland Delta’ located in north-western Botswana. The area includes permanent swamps which cover approximately 600,000 ha along with up to 1.2m ha of seasonally flooded grassland. The inscribed World Heritage property encompasses an area of 2,023,590 ha with a buffer zone of 2,286,630 ha. The Okavango Delta is one of a very few large inland delta systems without an outlet to the sea, known as an endorheic delta, its waters drain instead into the desert sands of the Kalahari Basin. It is Africa’s third largest alluvial fan and the continent’s largest endorheic delta. Furthermore it is in a near pristine state being a largely untransformed wetland system. The biota has uniquely adapted their growth and reproductive behaviour, particularly the flooded grassland biota, to be timed with the arrival of floodwater in the dry, winter season of Botswana.
The geology of the area, a part of the African Rift Valley System, has resulted in the ‘capture’ of the Okavango River that has formed the Delta and its extensive waterways, swamps, flooded grasslands and floodplains. The Okavango River, at 1,500kms, is the third largest in southern Africa. The Delta’s dynamic geomorphological history has a major effect on the hydrology, determining water flow direction, inundation and dehydration of large areas within the Delta system. The site is an outstanding example of the interplay between climatic, geomorphological, hydrological, and biological processes that drive and shape the system and of the manner in which the Okavango Delta’s plants and animals have adapted their lifecycles to the annual cycle of rains and flooding. Subsurface precipitation of calcite and amorphous silica is an important process in creating islands and habitat gradients that support diverse terrestrial and aquatic biota within a wide range of ecological niches.
Criterion (vii): Permanent crystal clear waters and dissolved nutrients transform the otherwise dry Kalahari Desert habitat into a scenic landscape of exceptional and rare beauty, and sustain an ecosystem of remarkable habitat and species diversity, thereby maintaining its ecological resilience and amazing natural phenomena. The annual flood-tide, which pulses through the wetland system every year, revitalizes ecosystems and is a critical life-force during the peak of the Botswana’s dry season (June/July). The Okavango Delta World Heritage property displays an extraordinary juxtaposition of a vibrant wetland in an arid landscape and the miraculous transformation of huge sandy, dry and brown depressions by winter season floods triggers spectacular wildlife displays: large herds of African Elephant, Buffalo, Red Lechwe, Zebra and other large animals splashing, playing, and drinking the clear waters of the Okavango having survived the dry autumn season or their weeks’ long migration across the Kalahari Desert.
Criterion (ix): The Okavango Delta World Heritage property is an outstanding example of the complexity, inter-dependence and interplay of climatic, geo-morphological, hydrological, and biological processes. The continuous transformation of geomorphic features such as islands, channels, river banks, flood plains, oxbow lakes and lagoons in turn influences the abiotic and biotic dynamics of the Delta including dryland grasslands and woodland habitats. The property exemplifies a number of ecological processes related to flood inundation, channelization, nutrient cycling and the associated biological processes of breeding, growth, migration, colonization and plant succession. These ecological processes provide a scientific benchmark to compare similar and human-impacted systems elsewhere and give insight into the long-term evolution of such wetland systems.
Criterion (x): The Okavango Delta World Heritage property sustains robust populations of some of the world’s most endangered large mammals such as Cheetah, White and Black Rhinoceros, Wild Dog and Lion, all adapted to living in this wetland system. The Delta’s habitats are species rich with 1061 plants (belonging to 134 families and 530 genera), 89 fish, 64 reptiles, 482 species of birds and 130 species of mammals. The natural habitats of the property are diverse and include permanent and seasonal rivers and lagoons, permanent swamps, seasonal and occasionally flooded grasslands, riparian forest, dry deciduous woodlands, and island communities. Each of these habitats has a distinct species composition comprising all the major classes of aquatic organisms, reptiles, birds and mammals. The Okavango Delta is further recognized as an Important Bird Area, harbouring 24 species of globally threatened birds, including among others, six species of vulture, the Southern Ground-Hornbill, Wattled Crane and Slaty Egret. Thirty-three species of water birds occur in the Okavango Delta in numbers that exceed 0.5% of their global or regional population. Finally Botswana supports the world’s largest population of elephants, numbering around 130,000: the Okavango Delta is the core area for this species’ survival.
The property covers most of the Delta, encompassing a vast area of over 2 million ha of substantially undisturbed wetlands and seasonally flooded grasslands. It is of sufficient size to represent all of the delta’s main biophysical processes and features and support its communities of plant and animal species. Because of its vast size and difficult access the delta has never been subject to significant development and it remains in an almost pristine condition. Tourism to the inner Delta is limited to small, temporary tented camps with access by air. Facilities are carefully monitored for compliance with environmental standards and have minimal ecological impact. Most importantly, the source of the Okavango Delta’s waters in Angola and Namibia remain unaffected by any upstream dams or significant water abstraction and the three riparian states have established a protocol under the Permanent Okavango River Basin Water Commission (OKACOM) for the sustainable management of the entire river system. OKACOM has formally supported the inscription of the Okavango Delta on the World Heritage List. It is imperative that upstream environmental water flows remain unimpeded and that over-abstraction of water, the building of dams and the development of agricultural irrigation systems do not impact on the sensitive hydrology of the property.
Concerns have been noted regarding fluctuating populations of large animals. Elephant numbers have been increasing whilst other species are reported as exhibiting significant declines. Data is variable, subject to different survey techniques and uncoordinated surveys undertaken by different institutions which all contribute to an unclear picture of the Okavango Delta’s wildlife. Authorities have initiated efforts to establish a comprehensive and integrated wildlife monitoring system that can accurately track population size and trends for the entire property, however ongoing work is needed to realise this. Causes of decline are attributed to seasonal variability, poaching (for example of giraffe for meat) and veterinary cordon fencing used to manage animal sanitation and control the spread of disease between wildlife and domestic stock. Mining activities including prospecting will not be permitted within the property. Furthermore, potential impacts from mining including concessions in the buffer zone and outside the buffer zone need to be carefully monitored and managed to avoid direct and indirect impacts to the property, including water pollution. The State Party should also work with State Parties upstream from the Delta to monitor any potential impacts, including from potential diamond mining in Angola, which could impact water flow or water quality in the Delta.
Protection and Management Requirements
The Okavango Delta comprises a mosaic of protected lands. About 40% of the property is protected within the Moremi Game Reserve, and the remainder is composed of 18 Wildlife Management Areas and Controlled Hunting Areas managed by community trusts or private tourism concession-holders. Legal protection is afforded through Botswana’s Wildlife Conservation and National Parks Act, 1992 and an associated Wildlife Conservation Policy. The Tribal Land Act of 1968 also applies to the property and the whole of the property (and the buffer zone) is communally-owned Tribal Land under the control of the Tawana Land Board.
As noted above the underlying causes of wildlife population declines are not clear, but an imposed hunting ban will further strengthen conservation measures in the property. The State Party is encouraged to develop a coordinated and systematic wildlife monitoring programme to establish population baselines for key species and to track trends. Veterinary cordon fences are known to cause significant disruption to wildlife at individual, population and species levels. Most of the property’s core and buffer zones are free of veterinary cordon fencing and the location of site’s boundaries was guided by these considerations. However, the Southern Buffalo Fence defines the southern boundary of the World Heritage property and whilst damage has compromised its effectiveness in disease control, it acts as a locally known demarcation to stop cattle grazing within the property. The Northern Buffalo Fence, also within the alignment of the property buffer zone, is known to disrupt connectivity in particular for the region’s Roan and Sable Antelope populations. Veterinary fencing is recognised as a sensitive, multi-dimensional issue. The State Party is encouraged to continue efforts to rationalize fencing, removing it when its effectiveness for disease control has become questionable or where more holistic approaches to animal sanitation and disease control are possible.
Ongoing vigilance is critical to ensure mining developments do not adversely impact the property. Past mining prospecting licences have been extinguished, and will not be renewed or extended. No extractive activity is undertaken in the property, and no new licenses will be issued within the property. The State Party should implement rigorous environmental impact assessment procedures for mining activities outside the property but which have the potential to negatively impact on its Outstanding Universal Value, to avoid such impacts. The Delta has been inhabited for centuries by small numbers of indigenous people, living a hunter-gatherer existence with different groups adapting their cultural identity and lifestyle to the exploitation of particular resources (e.g. fishing or hunting). This form of low-level subsistence use has had no significant impact on the ecological integrity of the area, and today mixed settlements of indigenous peoples and later immigrants to the area are located around the fringes of the delta, mostly outside the boundaries of the property. Continued special attention is needed to reinforce the recognition of the cultural heritage of indigenous inhabitants of the Delta region. Ongoing efforts should focus upon sensitively accommodating traditional subsistence uses and access rights consistent with the protection of the property’s Outstanding Universal Value. Efforts should centre on ensuring that indigenous peoples living in the property are included in all communications about the World Heritage status of the property and its implications, that their views are respected and integrated into management planning and implementation, and that they have access to benefits stemming from tourism. The State Party is encouraged to address a range of other protection and management issues to improve integrity. These include enhanced governance mechanisms to empower stakeholders in the management of the property; the development of a property specific management plan which harmonizes with planning in the wider landscape; ensuring adequate staffing and funding to build the capacity of the Department of Wildlife and National Parks; and programmes to strengthen the control and elimination of invasive alien species from the property.
1996: Okavango Delta is gazetted as a Ramsar, Wetland of International Importance.
IUCN MANAGEMENT CATEGORY
Miombo Woodland Woodland/Savanna (3.7.4)
South African Woodland/Savanna (3.8.4)
The Okavango Delta’s panhandle starts in close proximity to the Namibian border, where the water runs through Mahango Game Reserve and into Botswana. The panhandle subsequently fans out to encompass the wide delta we recognise today. The Okavango Delta Property lies between 21° 45’ E 23° 53’ E and 18°15’ S 20° 45’ S. The approximate centre of the site lies within the Moremi Game Reserve at 19° 17’ S and 22° 54’ E.
DATES AND HISTORY OF ESTABLISHMENT
1963: Moremi Game Reserve (4610 km2) created.
1964: Batawana announce first game reserve established on tribal land.
1965: Formal establishment of the Okavango Delta Reserve.
1976: Extension of the Okavango Delta boundaries eastwards to connect with the southwest corner of the Chobe National Park, and westwards to include the traditional protected area of Chief’s Island, enlarging the area by 3,900 km2.
1979: Reserve handed over to central government to be run by the Department of Wildlife and National Parks.
1992: New revision and extension of the boundaries of Moremi were again revised and extended.
1996: Okavango Delta is gazetted as a Ramsar Site (Wetland of International Importance).
The Department of Lands holds and administers the land on behalf of the Government. Most of the Delta land is communally owned, and is therefore held in trust for communities by the Tawana Land Board, which performs land management functions in accordance with the provisions of the Tribal Land Act of 1968.
The property covers 2,023,590 ha with an additional buffer zone of 2,286,630 ha.
The majority of the Okavango Delta lies beneath 1000m above sea level, and varies very little within the property itself.
The Okavango Delta is underlain by Proterozoic solid basement bedrock which is overlain by the Mesozoic Karoo Supergroup of rocks which lie beneath 20-300 m of Kalahari Sands. The solid basement bedrock is aligned into two trends of NW-SE (older) and NE-SW (younger). Renewed movement of the latter trend has caused the Delta to form in a down-faulted depression which is a part of the African Rift Valley System with the active Thamalakane, Kunyere and Gumare Faults.
Faults in the underlying geology that are orientated north-west to south-east confine the flow of the Okavango River south-eastwards towards the Delta area. Inside Botswana the upper Delta flows between two narrow parallel faults, creating a convoluted river meandering between permanent floodplains, approximately 20 km wide and 100 km long, called the ‘Panhandle’. Once out of the confines of these faults, the Okavango River slows and spreads outwards, creating a large triangular shaped alluvial and wetland fan, approximately 16 000 km2 in extent, as the slowing waters deposited their sediment load.
The Okavango Delta is situated in a semi-arid region with rainfall at Maun ranging from 195 to 940 mm per annum. During summer months (November to March) the average rainfall varies from 455 mm at Maun to 480 mm in the south and 490 mm in the northern part of the Delta, whilst the evapotranspiration rate is about 200 mm. The rainfall is highly variable with a coefficient of variation of annual rainfall of 35% characteristic of an arid environment. The monthly mean temperature range varies between 16-26°C in June (winter) to 28-40°C in October (summer), with the highest daily maximum temperature of 34-39°C in October and the lowest of 24-25°C in July. The mean minimum night time temperature during July can fall as low as 8°C (Mendelsohn & Obeid, 2004). Frosts do occur in winter but are uncommon and thin ice may form occasionally on very shallow waters in the Delta.
The Okavango Delta has a rich assemblage of plant species with a total of 1068 species of flowering plants and ten species of ferns, both covering 530 genera (Ramberg et al., 2006). There are five important plant communities in the perennial swamp: Papyrus Cyperus papyrus in the deeper waters, Miscanthus in the shallow-flooded sites, and between these two the reed Phragmites australis, Typha capensis and Pycreus communities occur. The swamp-dominant species, which are usually found in perennial swamp also extend far into the seasonally inundated areas. P. australis reed beds grow best in slow flowing waters of medium depth and are prominent at channel sides. On the islands and mainland edges above the flooded grasslands different communities of flora are found. These species are located according to their water preference, for example Philenoptera violacea requires little water, is found at the highest elevations in the perennial swamps, and is common on drier seasonal swamp islands. Trees restricted to islands within the perennial swamp are a mixture of the palm Hyphaene petersiana and Acacia spp.
On the mainland the vegetation is notably drier due to higher lying ground and is a characteristic mosaic of grassland and woodland communities comprised of trees, shrubs and understory herbs. Some of the principal genera, which make up the majority of the plant species within the Okavango Delta, include species of Acacia, Bosica, Combretum, and Terminalia. The exceptionally high plant diversity within this region is due in part to a periodical natural phenomenon – the annual flood in the dry season and the distinct rainy season in time of low water. Succession processes at different phases of development are therefore on-going in all plant communities in the Delta. These processes are the main driving forces for the species and habitats to diversify.
The Okavango Delta supports an outstanding assemblage of animal life (Junk et al., 2006), with many species being at their southernmost point of distribution in Botswana. Whilst there are a few endemic species in the Delta, there are no endemic large mammals or birds; however, the Delta does have an assemblage of large mammal and bird species not found elsewhere in Botswana, many of which are listed as threatened on the IUCN Red List. Examples of threatened mammals include: black rhinoceros Diceros bicornisi (CR), cheetah Acinonyx jubatus (VU), lion Panthera leo (VU), the African elephant Loxodonta Africana (VU) and the ground pangolin Manis temminckii (VU) (IUCN Red List, 2015). Botswana has the largest population of elephants in the world, with a growing population reported in the northern region (Mosepele et al., 2009). A Near Threatened species also present is the leopard Panthera pardus and the white rhinoceros Ceratotherium simum.
Botswana has 590 recorded species of birds (320 non-passerines and 250 passerines) of which 82% (482 species) are considered to occur in the property. Despite the low level of endemism found in the Okavango Delta, the near-endemic Slaty egret Egretta vinaceigula (VU) has over 85% of its global population confined to the property. The Okavango Delta also has the largest single population of the threatened wattled crane Grus carunculatus (VU) in the world, numbering around 1300 birds. There are an additional 20 globally threatened bird species which occur in significant numbers in the Delta, including six vulture species, and four other raptors. Lastly, the Delta is also of vital importance as a breeding area for water birds such as the marabou Leptoptilos crumeniferus and yellow-billed stork Mycteria ibis.
Aquatic biodiversity is of high significance in the Okavango Delta with an estimated 71 fish species (Rambert et al., 2006), many of which are an important food source for local people. The fish act as a crucial component of the food web, and facilitate the nutrient cycle (Mosepele et al., 2009). With regard to threatened fish species, there are two Tilapia species classed as Endangered (EN), in part because of the introduction of Nile tilapia (Oreeochromis niloticus). There is a low density of fish in the Delta compared to other wetland systems, with the local seasonal floodplains having higher yields.
With regard to the herpetofauna, there is only one threatened reptile in Botswana, the Southern African rock python Python natalensis (National Red List). The Nile crocodile Crocodylus niloticus has no protection status in Botswana, which may in part be why it is showing a declining population. A study between 2000 and 2002 found a total of 94 Odonata species (33 Damselflies and 61 Dragonflies) in the Okavango Delta (Kipping, 2003). Little research has been done on other clades such as Lepidoptera.
The Okavango Delta is one of only a few large scale alluvial fans in Africa, where the waters never reach the sea. The Okavango Delta is one of the least disturbed natural wetlands on earth, which is perhaps why there are such rich assemblages of flora and fauna (Junk et al,. 2006), including many iconic species such as the African elephant Loxodonta africana and lion Panthera leo. The Okavango Delta functions as an essential provider of ecosystem services to the surrounding communities, and as a fluvial lifeline to the myriad of species which reside within the protected area. The Delta further supports the livelihoods of approximately 130,000 local people, most of who depend on the Delta for resources.
The flooded grasslands and savannas biome, which the Okavango Delta represents, has been mentioned as a gap in representation of World Heritage sites, and the nominated property overlaps with protected areas which are considered highly irreplaceable, emphasising its global importance to species conservation (Le Saout et al., 2013)
The Okavango Delta population consists of five ethnic groups, each with a unique identity and language. They are: the Hambukushu, Dceriku, Wayeyi, Bugakhwe and IIanikhwe. The Hambukushu, Dceriku and Wayeyi are all Bantus who have traditionally been involved in millet agriculture as well as fishing and hunting. The Bugakhwe and IIanihwe are bushmen who have traditionally practiced fishing, hunting and the collection of wild foods. The ethnic groups of the region are renowned for their high level of hunting and fishing skills (Wawrzyniak, 2013).
LOCAL HUMAN POPULATION
According to the property’s nomination file, the oldest inhabitants within the Okavango Delta were the Basarwa, a diverse group who were later joined by the Bayei and Hambukushu in the 18th Century. Local populations were perhaps limited in size by the past presence of tsetse fly and malaria, which had an impact on their ability to successfully rear cattle or use other domestic animals. The prevalence of small communities changed with the formation of the Tawana state in the 19th Century. In 1964, there were roughly 42,000 residents in the region, by 1991, approximately 90,000 people lived in the broader Ngamiland province, and by 2006, this figure was closer to 130,000, and the figure is still rising. The State Party has confirmed there are currently 530 residents in three settlements within the property.
VISITORS AND VISITOR FACILITIES
There is a growing tourist industry in the Okavango Delta (Ramberg et al., 2006). The Department of Tourism noted in 2010 that the Okavango region, when compared to other regions in Botswana, had the highest number of accommodation facilities (116 facilities with 1125 rooms and 2,129 beds. As of 2005, approximately 50,000 tourists were visiting the Okavango Delta each year (Mbaiwa, 2003), a figure which will have risen subsequently. It is clear that the property’s exceptional biodiversity is a major asset, if not the main attraction for tourists, and as such it is important that the site’s biodiversity is preserved (Mladenov et al., 2007).
SCIENTIFIC RESEARCH AND FACILITIES
The University of Botswana Okavango Research Institute (ORI), located 15km NE of Maun and is mandated to carry out research on the biophysical and socio-ecological functioning of the Okavango Delta. The origins of the ORI can be traced back to the 1980s, when the University of Botswana created the Maun Field Research Station, but it was not until 1991 that the centre became a fully fledged national research centre.
The Okavango Delta site is managed according to several government plans, such as the Okavango Delta Management Plan (OMDP), which was adopted in 2008 and has a six year planning horizon. The ODMP vision is “A carefully managed, well functioning ecosystem that equitably and sustainably provides benefits for local, national and international stakeholders”. Additionally, the Permanent Okavango River Basin Water Commission (OKACOM), which is jointly managed through a tripartite agreement between Botswana, Namibia and Angola, was established to oversee the management and use of the water system on a sustainable basis. The Ministry of Environment, Wildlife and Tourism (MEWT) is the predominant user and manager of the resources found within the Okavango Delta World Heritage Site. The Okavango Delta has multiple management objectives separated into several different zones. The entire ‘core’ zone is wholly utilized for non-consumptive (photographic) tourism, where camps and lodge sites are leased to operators. The Moremi Game Reserve is zoned into a medium density tourism zone, a low density zone and a wilderness zone, in which there are progressively decreasing human activities. There are also nine controlled hunting areas that are zoned for community management, while a further twelve are zoned for commercial management.
Some of the highlighted barriers to conservation in the area include: the location and extent of fires, the changing hydrology (and the affect this has on vegetation distribution), the abundance and movement of key herbivore and carnivore species, fish catches, and the use of traditional and motor boats. Poaching does occur within the property even though anti-poaching activities and wildlife management activities are carried out by patrol staff in Moremi Game Reserve. On-the-ground management of wildlife is highlighted as an area which could benefit from being expanded. The sourcing of management funding has also been indicated as an area which could be improved. One of the reasons for this is that there is as of yet no method of retaining funds created within the property, from tourism for example, as all this revenue is given to the national treasury.
As of 2014 there were four professional staff and eight support staff in Maun responsible for the overall coordination and implementation of the Management Plan, and a further 180 staff classed as professionals or technicians. There are a further four stations in Moremi with an additional 25 staff.
The Okavango Delta is managed by a number of organisations and institutions. The implementation of the National Development Plan and District Development Plan are primarily financed by the government. Nationwide, the Ministry of Environment, Wildlife and Tourism receives 890 million Pula (US\$108 million), which is divided between the district offices. The district offices of the ministerial departments are given approximately seven million Pula annually (US\$875,000), a portion of which goes into the management of resources within the Delta.
Permanent Secretary Ministry of Environment Wildlife and Tourism Address: Private Bag B0199, Gaborone.
The principal source for the above information was the original nomination for World Heritage status.
Le Saout, S. et al. (2013). Protected areas and effective biodiversity conservation. Science, 342 (6160), 803-805.
The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 11 February 2015
Junk, W. et al. (2006). The comparative biodiversity of seven globally important wetlands: a synthesis. Aquatic Sciences, 68 (3), 400-414.
Kipping, J. (2003). Odonata recorded from the Okavango Delta, in Alonso, L.E. & L. Nordin (eds), 137- 140.
Mbaiwa, J. E. (2003). The socio-economic and environmental impacts of tourism development on the Okavango Delta, north-western Botswana. Journal of Arid Environments, 54 (2), 447-467.
Mendelsohn, J. & El Obeid, S. (2004). Okavango River: The Flow of a Lifeline. Struik.
Mladenov, N. et al. (2007). The value of wildlife-viewing tourism as an incentive for conservation of biodiversity in the Okavango Delta, Botswana. Development Southern Africa, 24 (3), 409-423.
Mosepele, K. et al. (2009). Fish, floods, and ecosystem engineers: aquatic conservation in the Okavango Delta, Botswana. BioScience, 59 (1), 53-64.
Ramberg, L. et al. (2006). Species diversity of the Okavango Delta, Botswana. Aquatic sciences, 68 (3), 310-337.
Vié, J. C. et al. (2009). The IUCN Red List: a key conservation tool. Wildlife in a changing world–An analysis of the 2008 IUCN Red List of Threatened Species, 1.
Wawrzyniak, S. (2013). Khoisan–the Best Hunters in the World. INVESTIGATIONES LINGUISTICAE, 28