National Wetland Map 5: An improved spatial extent and representation of inland aquatic and estuarine ecosystems in South Africa

  • Heidi van Deventer 1. Council for Scientific and Industrial Research (CSIR), PO Box 395, Pretoria 0001, South Africa; 2. School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand (WITS), Private Bag 3, Johannesburg 2050, South Africa http://orcid.org/0000-0002-7854-2155
  • Lara van Niekerk 1. Council for Scientific and Industrial Research (CSIR), PO Box 320, Stellenbosch 7600, South Africa; 2. Institute for Coastal and Marine Research (CMR), Nelson Mandela University, Private Bag X6531, Port Elizabeth 6530, South Africa http://orcid.org/0000-0001-5761-1337
  • Janine Adams Department of Botany, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031, South Africa http://orcid.org/0000-0001-7204-123X
  • Millicent Ketelo Dinala South African National Biodiversity Institute, Private Bag x101, Pretoria, 0001, South Africa
  • Ridhwannah Gangat School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand (WITS), Private Bag 3, Johannesburg 2050, South Africa http://orcid.org/0000-0003-3334-5956
  • Stephen J Lamberth 1. Institute for Coastal and Marine Research (CMR), Nelson Mandela University, Private Bag X6531, Port Elizabeth 6530, South Africa; 2. Department of Environmental Affairs: Fisheries Research and Development, Private Bag X2, Vlaeberg 8018, Cape Town, South Africa; 3. South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown 6140, South Africa
  • Mervyn Lötter Mpumalanga Tourism and Parks Agency (MTPA), Private Bag X1088, Lydenburg 1120, South Africa
  • Namhla Mbona South African National Biodiversity Institute, Private Bag x101, Pretoria, 0001, South Africa http://orcid.org/0000-0001-8760-7857
  • Fiona MacKay 1. Oceanographic Research Institute, South African Association for Marine Biological Research, PO Box 10712, Durban 4056, South Africa; 2. School of Life Sciences, University of KwaZulu-Natal, Durban, 3630, South Africa
  • Jeanne L Nel 1. Wageningen Environmental Research, Postbus 47, 6700 AA, Wageningen, The Netherlands; 2. Sustainability Research Unit, Nelson Mandela University, Private Bag X6531, George 6530, South Africa http://orcid.org/0000-0001-6220-770X
  • Carla-Louise Ramjukadh Council for Scientific and Industrial Research (CSIR), PO Box 320, Stellenbosch 7600, South Africa
  • Andrew Skowno 1. South African National Biodiversity Institute, Private Bag x101, Pretoria, 0001, South Africa; 2. 14Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch, South Africa http://orcid.org/0000-0002-2726-7886
  • Steven P Weerts 1. Council for Scientific and Industrial Research (CSIR), 359 King George V (5th) Avenue, Durban 400, South Africa; 2. Department of Zoology and CRUZ, University of Zululand, Private Bag X1001, Kwadlangezwa 3886, South Africa http://orcid.org/0000-0002-9826-3209
Keywords: wetland inventory, National Wetland Map, inland aquatic ecosystems, estuarine functional zone, macro estuaries, micro estuaries, National Biodiversity Assessment, Sustainable Development Goal (SDG) reporting, Ramsar

Abstract

The improved representation of freshwater and estuarine ecosystems and associated data was a key component of the 2018 National Biodiversity Assessment, and is an essential step in enhancing defensible land use planning and decision making. This paper reports on the enhancement of the National Wetland Map (NWM) version 5 for South Africa and other data layers associated with the South African Inventory of Inland Aquatic Ecosystems. Detail is provided on (i) the extent of wetlands mapped in NWM5, compared to previous versions of the NWMs; (ii) the improved extent of inland wetlands mapped in focus areas in NWM5 relative to NWM4; (iii) the type of cover associated with the wetlands (inundated, vegetated or arid); (iv) the ecotone between rivers and estuaries; and (v) level of confidence for the inland wetlands in terms of how well the extent and hydrogeomorphic units were captured for each sub-quaternary catchment of South Africa. A total of 4 596 509 ha (3.8% of South Africa) of inland aquatic ecosystems and artificial wetlands have now been mapped, with NWM5 delineating 23% more inland wetlands (2 650 509 ha or 2.2% of SA) compared with NWM4. The estuarine functional zone, which encapsulates all estuarine processes, and associated habitats and biota, was refined for 290 systems totalling 200 739 ha, with the addition of 42 micro-estuaries totalling 340 ha. Nearly 600 000 ha (0.5% of SA) of artificial wetlands were mapped in SA. Inland wetlands are predominantly palustrine (55%), with some arid (34%) and a few inundated systems (11%). Ecotones between rivers and estuaries, ecotones where biota and processes continuously vary from freshwater to estuarine, formed a small fraction (<1.5%) of river total extent (164 018 km). Most inland wetlands (~70%) had a low confidence ranking for designation of extent and typing, because they were not mapped by a wetland specialist and not verified in the field. Future improvements of the map should be focused on catchment-based improvements, particularly in strategic water-source areas, areas of high development pressure and those with low confidence designation.

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Published
2020-01-30
Section
Research paper