Western Cape Wetlands Directory Data

This layer was created using point data generated from various reports and studies included in the Western Cape Wetland Directory database (Dallas and Seymour 2006). Wetlands were broadly defined using the definition used by the RAMSAR convention: `areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tides does not exceed 6 meters` (Peck 1999) `This includes all aquatic ecosystems such that wetlands included fall into three groups of marine, estuarine and inland systems (see Dallas and Seymour for more details) Where studies specify latitudes and longitudes (lat-longs), theses were used to point locations of the wetlands to which they referred. For studies which did not state (lat-longs), but which described proximities to landmarks or towns, this information, together with existing GIS coverages (i.e. sensitive wetlands coverage (Shaw and de Villiers 2001) and the CAPE freshwater component (van Nieuwenhuizen and Day 2000) was used to generate point localities. These are indicated in the directory: if lat-longs given are derived from the original data source, they are denoted as `data source`. If they were derived using landmarks and supplementary GIS coverages, they are denoted as `map`. Owing to varying accuracy and settings of GPS instruments and data sources, points often did not align with each other or with the sensitive wetlands layer (Shaw and de Villiers 2001) or the CAPE freshwater component (van Nieuwenhuizen and Day 2000). These points were therefore nudged so that they would align, and generated new lat-longs for these points. The original data remain within the database, but the point GIS coverage (Western Cape Directory Data.shp contains modified lat-longs.