A brief overview of wetland definition, functions and values and classification is presented. I conclude that wetlandsof arid regions, even where the interval between flooding may be several years, can be accommodated within existing classification system. A preliminary analysis of the return frequency of extreme rainfall events indicates that temporary waterbodies in Namibia may provide adequate for wetland processes such as breeding of waterfowl once in every five to ten years. I suggest that because of regional variations in rainfall and the wide distribution of these wetlands, suitable habitats are likely to be available for nomadic species at considerably shorter intervals. Keywords: Brackish, Coastal zones, Controlling water cycles, Ecosystem type, Estuarine, Fen, Fresh water, Lacustrine, Life-support systems, Marine, Marsh, Palustrine, Peatland, Riparian, Riverine, Salt, Vegetation and Waterbirds.