Ecosystem Services in the Gariep River basinThe Southern African Millennium Ecosystem Assessment (SAfMA) included eight assessments, one of which that was an assessment of the Gariep River basin(this includes a large portion of the the Orange-Senqu River basin). The SAfMa defined the Gariep River basin as “the area of South Africa and Lesotho drained by the Senqu-Gariep-Vaal River system, as well as two primary catchments connected to this system by major water transfer schemes: the Tugela (or Thukela) in KwaZulu-Natal Province, and the Great Fish in the Eastern Cape Province” (SAfMA 2004). Therefore, it is important to note that Namibia and Botswana are not included in this assessment. The table below illustrates the ability of ecosystems in the Gariep River basin study area to supply basic requirements for human well-being such as food, water, energy and minerals. This looks at whether there are adequate supplies and effective distribution, associated health impacts, and sustainability of provision. Table: Ability of Ecosystems in the Gariep River basin to fulfill basic requirements for human well-being.
Source: Bohenski et al. 2004 Hotspots are indicated by “irreplaceable areas for food production (able to supply caloric and protein requirements) and for biodiversity, areas in which water requirements are approaching available surface water supply, areas in which groundwater is high in salinity, municipalities in which one quarter of households or fewer have access to electricity from a local authority, municipalities with significant mining activity, and a synthesis map of several key services (Bohenski et al. 2004)”. Regions in the basin that were identified as being critical for the provision of food or high levels of surface water runoff also coincided with the regions that had a high biodiversity value. The high levels of agriculture and urbanisation are well-known concerns in the basin and have already affected its ecological integrity, with most of the indigenous grasslands under severe threat. The basin is a source of mineral wealth and contains several irreplaceable biodiversity sites, such as the Succulent Karoo (see the Box below) due to the concentration of many endemic species (Bohenski et al. 2004). Box: Succulent KarooThe Succulent Karoo’s botanical diversity is unparalleled by any other arid region on Earth. This eco-region is home to over 5 000 higher plant species, nearly 40% of which are endemic, and 18% of which are threatened. It has the richest succulent flora in the world, harboring about one-third of the world’s approximately 10 000 succulent species. Other unique features include the diversity of miniature succulents (435 spp.) and geophytes (630 spp.). The eco-region is also a center of diversity and endemism for reptiles and many invertebrate taxa, especially monkey beetles (Rutelinae: Hoplinii). This eco-region extends down the western coast of Namibia from the town of Luderitz into South Africa, and then penetrating further inland. It comprises two major biogeographical domains, the Namaqualand-Namib Domain and the Southern Karoo Domain (Jürgens 1991). The Namaqualand-Namib Domain encompasses the fog-affected coastal plain and adjacent escarpment in the west. It is made up of several sub-regions: the Sperrgebiet of southern Namibia; the Richtersveld, which is a desert mountain region adjacent to the Orange River; the Sandveld, or sandy coastal plain, south of the Orange River; the Hardveld, or granitic uplands, of the Great Escarpment; the Kamiesberg, a granite massif of 1 800 m along the escarpment; and the quartz-strewn plains of the Knersvlakte in the extreme south. This domain receives most of its rain in winter. Source: World Wildlife Fund 2001
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