b5cc8af3-d85d-4423-9096-fe8d2a65ae0a SANBI The Metadata Manager +27 21 799 8738 Kirstenbosch Research Centre Cape Town Claremont 7735 South Africa bgishelp@sanbi.org.za 2022-08-18T15:16:48 SANS 1878 FGDC-STD-001-1998 WGS 1984 Mean Annual Runoff 2013 2013 1.0 This GIS layer represents the Strategic Water Source Areas (SWSAs) as “fuzzy blobs” for South Africa, Lesotho and Swaziland. Strategic Water Source Areas are those areas that supply a disproportionately high amount of the country’s mean annual runoff, in relation to their surface area, here defined as those areas that contribute >50% of the country’s mean annual runoff. These areas have been mapped for South Africa, originally derived from a 1 x 1 minute grid (MAR_SWSA) which is also on BGIS. They make up 8% of the land area across South Africa, Lesotho and Swaziland but provide 50% of the water in these countries. The intention of the SWSA_blobs layer is to denote fuzzy boundaries around general areas considered to be Strategic Water Source Areas, and to attach names to these “blobs”. “Blobs” for the Strategic Water Source Areas were derived by roughly circling the general area where mean annual runoff for South Africa (mm/year for each 1 x 1 minute grid cell) = 135 mm/year. This was based on MAR_SWSA (also on BGIS) which represents mean annual runoff derived from disaggregating the Water Resources Assessment 2005 data (Middleton and Bailey 2009), which represents the most commonly-used national mean annual runoff data used by the Dept of Water Affairs for water resources planning and management. Blobs depict and name general areas of Strategic Water Source Areas for South Africa. Strategic Water Source Areas are those areas that supply a disproportionate amount of mean annual runoff to a geographical region of interest. Dr Jeanne Nel Principal Researcher The GIS Officer + 27 (21) 888 2484 Stellenbosch Western Cape 0001 South Africa jnel@csir.co.za Strategic Water Source Areas South Africa - 50000 environment 2016-01-01 15.292968749999995 33.486328125 -35.17380831799959 -21.616579336740585 SANBI bgishelp@sanbi.org.za ZIP 1 http://bgismaps.sanbi.org/server/rest/services/BGIS_Projects WWW:LINK-1.0-http--link A list of services published are available at this URL. BGIS Map Services http://bgis.sanbi.org/SpatialDataset/Detail/505 WWW:LINK-1.0-http--related A list of spatial data-sets are available at this URL. BGIS Spatial Datasets Methodology: On-screen digitizing of oval polygons roughly around Strategic Water Source Areas identified according to MAR_SWSA, SWSA_grid and SWSA_poly (GIS layers that are all on BGIS). Available documentation: Nel, J.L, Colvin, C., Le Maitre, D.C., Smith, J. and Haines, I. 2013. South Africa’s Strategic Water Source Areas. CSIR Report CSIR/NRE/ECOS/ER/2013/0031/A, CSIR, Stellenbosch, South Africa.