A pixel in the Lydenburg area, at 1600m resolution, is selected to illustrate how this analysis can yield areas where there are differences in the altitude values. This initial investigation shows that DEM2 and DEM8 can be used to highlight areas of possible errors in DEM16. DEM8 reflects that the altitude for this pixel is 2772m and this pixel is sub-divided into four by four 200m pixels and the altitude values from DEM2, the altitude from the topographical map at the centre of the pixel and the representative or average altitude was determined for these 16 pixels, Fig. 2 . Manual inspection of the area reveals that the average altitude is approximately 2390m. Mowbray, South Africa.
Mapping mean annual and other rainfall statistics over southern Africa.
Univ. of Natal, Dept. Eng., ACRU Report 27, Water Research Commission, Pretoria, South Africa.