coaltech upper olifants river catchment wetland inventory ...

4. METHODS
4.1 Aerial photographs
Georeferenced aerial photographs could only be obtained for a small portion of the
catchment. Digital1:50 000 aerial photographs (not georeferenced), were obtained from the
Chief Directorate: Surveys and Mapping at the Department of Land Affairs, Mowbray,
Cape Town for the whole catchment. The aerial photographs were georeferenced with
ArcView 9.1, using the 1:50 000 topographical map shapefile layers as a reference. The
spatial reference of the aerial photographs is geographic, with the ellipsoid as WGS84. The
aerial photographs were taken during a 2003/2004 survey of the area.
We investigated Google Earth for potential to use in this survey, but found the quality of the
images too poor to be of use for this project.
During phase 2 of the project, aerial photographs abtained from some of the mines were
used to verify the presence of wetlands indicated in the UORC wetland database. These
aerial photographs only cover a small portion (approximately 10%) of the catchment.
4.2 Compilation of the wetland and dam layers
Three existing wetland databases were incorporated into one to obtain a baseline wetland
database for the area. The wetland databases were:
• The wetland database of the catchment as included in Palmer et al (2002) (Figure 9);
• The draft Mpumalanga C-Plan wetland database (Figure 10); and
• The water bodies’ shapefile layer of the 1:50 000 topographical maps (Figure 11).
Wetland Database for UORC - 70 -