Improving the spatial inland wetland data for National Wetland Map 5 in South Africa to inform policy and decision-making.
Abstract
It is widely agreed that it is a high priority to achieve an accurate map of South Africa's wetlands. Such a map will provide a critical baseline into the future, where, over time, the extent to which different forms of land use impinge into wetland extents can be mapped, and inferences can be drawn in terms of wetland condition and functioning. Compiling inventories of wetlands in order to collect information on their location, size, type, condition and other important features is fundamental to a strategic approach to the protection, rehabilitation and sustainable management of wetlands. Such inventories underpin the ability to develop policies, strategies and plans that are responsive and relevant to the problems identified and focus on matters of priority. A strategic framework can guide fine-scale local efforts so that they contribute effectively to wetland management and conservation objectives at regional, national and even international scales. Inventories provide information needed to prioritise the most important wetlands systematically and allocate limited resources accordingly. The National Wetland Inventory (NWI), housed within the South African National Biodiversity Institute (SANBI), is the current repository of national spatial information regarding wetlands in South Africa. The NWI generates the National Wetland Map (NWM), which is the primary wetland layer used in national planning projects such as the National Freshwater Ecosystem Priority Areas (NFEPA) and the 2011 National Biodiversity Assessment (NBA). The NFEPA project created a wetlands layer that was adopted by SANBI as NWM4. Based on the available data at the time of preparation of NWM4, the 2011 NBA published by SANBI identified wetlands as the most threatened ecosystem type in South Africa, with 48% of wetland ecosystem types classified as critically endangered, 12% as endangered and 5% as vulnerable. Much funding and specialist time has already been invested by the Water Research Commission (WRC), the Council for Scientific and Industrial Research (CSIR), the Department of Water and Sanitation, the Department of Environmental Affairs and SANBI in the collaboration that generated the Atlas of Freshwater Ecosystem Priority Areas in South Africa and its supporting technical and implementation manuals. The NFEPA project was a tremendous step forward in consolidating existing knowledge and generating new knowledge on the distribution, type and condition of freshwater ecosystems. However, experience in using the maps has shown that there still room for considerable improvement in both the wetland map (the mapping accuracy was low in extensive areas) and assessing the ecological condition of South Africa's wetlands (which was conducted at a very low resolution). For example, the wetland area mapped in WRC Project TT614/14, completed in 2015, that focused on the Mpumalanga Highveld coalfields showed a 75% improvement compared with the NFEPA wetlands layer, also referred to as NWM4. As a consequence of this mapping work, 23 wetland types had their threat status moved to less threatened classes for the Mpumalanga Highveld. Another recent study showed that fine-scale mapping increased the area of wetlands within the municipal boundaries of the City of Cape Town by almost 50% compared with NWM4. Report TT614/14 concluded that sufficient data has been collected to indicate that the weaknesses in NWM4 are severe and widespread, which warrant investment to improve the quality of the NWM as a matter of urgency. It also reiterated the consensus view within the community of practice that the magnitude of the task of improving the quality of wetland inventory data for the country as a whole is beyond the ability of any single organization. The report further recommended that additional research and development are needed to improve techniques to determine the wetland type and condition accurately at desktop level.