NWM5_Confidence_map_AEA

South African Inventory of Inland Aquatic Ecosystems.

The Confidence map is part of the South African Inventory of Inland Aquatic Ecosystems (SAIIAE) and was compiled to identify areas where wetland extent and HGM units attained at a higher level of certainty compared to other areas. Mapping the locality of wetlands is essential so that they may be classified into the different wetland ecosystem types across the country, which in turn can be used along with other data to identify wetlands of significance.

Van Deventer, H., Smith-Adao, L., Mbona, N., Petersen, C., Skowno, A., Collins, N.B., Grenfell, M., Job, N., Lötter, M., Ollis, D., Scherman, P., Sieben, E. & Snaddon, K. 2018. South African National Biodiversity Assessment 2018: Technical Report. Volume 2a: South African Inventory of Inland Aquatic Ecosystems (SAIIAE). Version 3, final released on 3 October 2019. Council for Scientific and Industrial Research (CSIR) and South African National Biodiversity Institute (SANBI): Pretoria, South Africa. Report Number: CSIR report number CSIR/NRE/ECOS/IR/2018/0001/A; SANBI report number http://hdl.handle.net/20.500.12143/5847.

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The confidence rating map should always be consulted to assess whether the NWM5 is fit for purpose. Please see Van Deventer et al., 2018 for more information.

WGS 1984

Projection: Albers

False_Easting: 0.0

False_Northing: 0.0

Central_Meridian: 25.0

Standard_Parallel_1: -24.0

Standard_Parallel_2: -33.0

Latitude_Of_Origin: 0.0

Linear Unit: Meter (1.0)

A confidence map was compiled to identify areas where the extent and HGM units attained a higher level of certainty compared to other areas. For the purpose of this first version of the SAIIAE, higher levels of certainty are associated with areas that have been visited in-field by a wetland specialist(s) over multiple seasons and cycles of the hydroperiod of a wetland, and accurately represented in the dataset. Accuracy, on the other hand, reflects the degree to which the spatial boundaries and/or attributes of the wetlands match those in the real world. A higher confidence score would imply an increase in accuracy, assuming that the spatial boundaries of a wetland had been informed by water, soil and vegetation indicators, and recorded with differential GPSs. Low confidence scores would imply the inverse.

The confidence rating map should always be consulted to assess whether the NWM5 is fit for purpose. The confidence of estuarine and coastal ecosystems is not reflected in this confidence map (Figure 4.16). In general, areas mapped as a Low confidence, is likely to still have a 50% omission error, though the commission error may have been reduced to < 10% compared to the previous versions of the NWMs. The appropriate scale of use would be 1:50 000. Where the confidence rating is Low to Medium, Medium and Medium to High, we estimated the omission error to be < 30% and the commission error < 10%. The appropriate scale of use would be 1:10 000.

Please see Van Deventer et al. (2018) for more information.

SANS 1878

FGDC-STD-001-1998