The Okavango Delta Region

Okavango Delta in Botswana: A Socio-Economic Perspective

3.3 The Okavango Delta Region

The Okavango Delta occupies the northwestern region of Botswana, in the Ngamiland district. This district is the third largest in the country, with a total area of 109 130 square kilometers, and forms part of the international boundary between Botswana and Namibia. Both the geographic location and the physical characteristics of the district give it remote area status. Soils are generally dominated by heavy Kalahari sand, and the fluctuating waters of the Okavango swamp can make traveling within this district difficult (Ross, 1987; Republic of Botswana Environmental Statistics, 2000).

The Okavango delta is a 13 000 square kilometre lush, tropical wetland, surrounded by

Kalahari Desert savannah, and is recognized as one of the world's largest inland

delta's (Ross, 1987). However, not all of the 13000 square kilometres is a flooded

'swamp'. The delta fluctuates in size as a result of a complex relationship involving an

annual flood from Angola and local rainfall events. In the current climate regime, and

during the driest time of the yearly cycle, the perennially flooded part of the delta will

amount to only an estimated 6 000 square kilometers. At the height of the flood as

much as 13 000 square kilometers may be inundated, and there is geomorphologic evidence which suggests that in the past, the delta may have been as large as 22 000 square kilometers (http://www.places.co.za).

The Okavango River rises in the highlands of southern Angola, and cuts south through Namibia's Caprivi Strip, and then enters northwestern Botswana (Ross, 1987; Bock, 1993; Hitchcock, 2000). It is the last surviving remnant of the great Lake Makgadikgadi, whose waters and swamps once covered much of the middle Kalahari. It is also

closely connected with the Kwando-Linyanti-Chobe swamps and river systems to the northeast. It is thought that in the past the Okavango, Chobe, Kwando and upper Zambezi waterways flowed as one massive river across the middle Kalahari, to join the Limpopo River and then flow to the Indian Ocean. The flow of this river was later impeded by tectonic movements in the earth's crust causing a damming back of the giant river which resulted in the formation of a series of huge and complex swamps (Ross, 1987). As the Okavango River left the humid highlands of southern Angola, and entered the arid, extreme flatness of the Kalahari, it slowed and deposited its sediment load (http://www.icun.org ... html ; Ross, 1987; Hitchcock, 2000). As a result, channels became blocked and the water sought other courses, continuing to drop its sediments wherever it traveled. Over time, around two million tons of sand and debris were deposited over the Kalahari, creating the characteristic fan shape of the Delta. The Okavango's waters still cut paths through these deposits, and drop their sand load, causing the channels to continue changing direction (Ross, 1987).

Two parallel faults now determine the direction in which the Okavango River enters the

Kalahari Basin, in an area in the northern part of the delta called the Panhandle (Ross,

1987; Hitchcock, 2000). Here there is still enough of an elevation change that the water

fans out for only fourteen kilometers. This area contains immense 'islands' of densely

packed papyrus and reeds. On either side of the Panhandle, Kalahari Desert savanna

extends for hundreds of kilometres. Further south the narrow Panhandle gives way to

the Delta, which spreads out for over a hundred kilometres to the south, east and west

(Ross, 1987; Hitchcock, 2000). This area is a patchwork of swampy land and islands,

with a rich diversity of mammals .and birds. Central to this ecosystem is the annual

flood which brings water with nourishment to the Delta. The summer rains in Angola

bring a flood in the winter months (June to September). The flood makes travel for both

people and wildlife difficult, and the islands become surrounded by water. Once the

flood recedes, the area can become quiet dry, the formerly riverine floodplains

becoming grassy plains. In many ways this flood determines the lifecycle, not only for the animals and plants, but also for the people of the Delta (Bock and Johnson, 2002).

3.3.1 Climate

The Ngamiland district experiences a semi-arid to arid climate. The presence of a southern sub-tropical high-pressure belt influences the climate, causing a large-scale downward movement of air. Convectional rainfall is common in the area, which, like elsewhere in Botswana, is erratic. Annual rainfall levels vary from 450 millimeters to 660 millimeters in the Ngamiland district and tend to occur during the months of November to March. The southward movement of the Inter Tropical Convergence Zone (ITCZ) also adds to the relatively high rainfall amounts in the area - in

comparison to the rainfall levels throughout the rest of Botswana. Maun receives an average of 545 millimeters of rainfall annually. The average minimum temperatures vary from 15 degrees Celsius to 20 degrees Celsius for winter and summer months, respectively. Maximum temperatures range from 25 degrees Celsius to 34 degrees Celsius, with peaks in October to November (Makhwaje

et aI,

1995; Ndubano, 2000).

3.3.2 Soil and Vegetation

The vegetation in the Okavango delta region can be broadly divided into Northern Kalahari Tree and Bush Savannah and Aquatic Grassland. The major soil type in the Ngamiland district is the arenosols, which is a typical Kalahari-sand type of soil. This soil-type fringes the Okavango delta and Panhandle, but clay rich luvisols are dominant within the delta itself. These luvisols are important for arable agriculture in the area (Makhwaje

et aI, 1995).

3.3.3 Wildlife

Ngamiland district contains a large diversity of wildlife which is an important natural

resource to Botswana. According to the eighth National Development Plan (NDP 8),

(1998 to 2003), wildlife has the potential to present an alternative to the countries

dependence on minerals by way of tourism (Republic of Botswana Environmental Statistics, 2000).

In order to conserve this wildlife resource, several national parks and game reserves have been developed throughout the country, covering different ecological zones. The Moremi National Park is situated on the northeastern side of the Okavango delta.

Established in 1965, this reserve covers some 3 900 square kilometres of formerly

communal land. With habitats ranging from dry savannah woodland, semi-desert like

Knobthorn

(Acacia nigrescens) and Mopani (Colophospermum mopane) forests,

riparian woodland, floodplain and reed beds to permanent papyrus

(Cyperus papyrus)

swamp, it is arguably the Okavango delta's primary tourist attraction (Republic of

Botswana Environmental Statistics, 2000; Ndubano, 2000).