AfriBasin

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Overview

Supported by START/NORAD and UNESCO/IOC and hosted by UNEP’s Regional Office for Africa in co-operation with the Pan African START Secretariat, PASS, the second LOICZ AfriBasins workshop took place in Nairobi, Kenya 29 Oct-2 Nov 2001.  Building on AfriBasins I, two working groups (western and eastern coasts) identified coastal change and river catchment-based forcing of change in eight sub-regions by considering coastal geomorphology, coastal habitats/biodiversity, climatic conditions, people relationships (demography and drivers), catchment size and seasonal runoff, land use and cover.

 

Catchments assessed in AfriBasin

 

The sub regions were:

·        the Nile, including the wider coastal stretches influenced by the Nile catchment reflecting land-based drivers including the Aswan dam, Cairo urbanisation and agriculture in the Delta.

·        East Africa (Somalia to northern Mozambique), featuring the small- and medium-sized catchments under monsoonal forcing (seasonal flushing) and subject to damming, and extensive coral reefs.

·        Southern/central Mozambique, again with high seasonality in runoff characteristics and transboundary issues including damming and impacts such as salinisation in the coastal zone.

·        South-east Africa, ranging from subtropical in the north to the warm temperate on the Cape coast and characterised by generally small catchments that are subject to various human use patterns with plans in place for intensive damming.

·        South-west Africa (Cape of Good Hope to southern Angola), mainly dominated by the upwelling system of the Benguela current, cool and temperate in the south, arid in the north with limited river runoff to the coastal sea.

·        the Congo, a central African sub-region with a very large catchment with extensive rainforest but little information available about its land-based drivers and how they relate to coastal issues.

·        West Africa, featuring a variety of large rivers subject to major damming resulting in reduced sediment and water fluxes and reduced coastal stability as a growing threat to the lagoon-based cities.

·        North-west Africa, a relatively arid sub-region with seasonal runoff and, at least in Morocco, major human pressure through diversion and damming causing a variety of coastal change issues. 

 

Results of the assessment scaled up to the continental level. (Results for individual catchments and regions are in the report)

Coastal geomorphological change, erosion and sedimentation were identified as a significant and progressive impact in nearly all of the sub-regions, the problem being acute on the Nile delta and in West African lagoon systems. Damming was viewed as the principal driver in such change, with consequent reductions in stream flow and sediment flushing.  Other coastal impacts ascribed to river damming include salinisation, e.g., in the Incomati estuarine plain in Mozambique, and nutrient depletion in coastal seas e.g., Kwazulu-Natal. In most sub-regions deforestation and agriculture were seen as important drivers, particularly in respect of coastal sedimentation from medium and small catchments, e.g. the Tana and Sabaki rivers in Kenya. Human settlement was regarded as a major contributor to eutrophication and the occurrence of aquatic weeds in the large West African catchments.  Elsewhere, while eutrophication and pollution were recognised as important issues, they were related in many cases to local (coastal) urban-industrial sources e.g., Alexandria, Mombasa, Saldanha Bay and Cape Town. Loss of biodiversity or biological functioning was another common issue, though related probably to complex ranges of human and natural drivers. In general these data are characteristic of developing economy situations where economic growth and water use exceed development of the necessary urban and industrial infrastructure. This finding parallels those made in the South American (Lacerda et al. 2002 – LOICZ R&S 21 in press), and East Asian basins assessments (Hong et al., in prep.). However, the heterogeneity of the African sub-regions seems to be more pronounced, making the ranking of issues and drivers in Africa a more complex challenge. 

Late 2002 a project started (AfriCat) in four African catchments focusing on hydrological issues.

DOCUMENTS:

Executive summary (PDF files, 270 Kb) 

Participants first workshop (PDF file, 25 Kb)

Participants second workshop (PDF file, 29 Kb)

Download full report (PDF file, 54 MB)

Download AfriBasin presentation (R. Arthurton) prepared for the Miami-Loicz meeting (May 2002) (PowerPoint file 351kB)

 Regional Coordinator :

Prof. Dr. E. Odada
University of Nairobi
eodada@uonbi.ac.ke

 

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