Indications of progressive desiccation of the Transvaal Lowveld over the past 100 years, and implications for the water stabilization programme in the Kruger National Park

Abstract

All available rainfall statistics recorded for the Kruger National Park area since 1907, coupled with an analysis of all the historical climatological data on hand, appear to confirm the quasi-twenty-year rainfall oscillation in precipitation pattern for the summer rainfall area. This was first pointed out by Tyson & Dyer (1975). The dendrochronological data obtained by Hall (1976) from a study of growth rings of a very old yellowwood tree (Podocarpus falcatus) in Natal, also appear to indicate a superimposed, long-term (80-100 years) pattern of alternate below- average and above-average rainfall periods. The historical data relating to climate in the park, during the past century or two, seem to bear out such a pattern. If this can be confirmed, it will be an enormous aid not only in wildlife-management planning, but also to agriculturists, demographic planners and others. It would appear that the long, relatively dry rainfall period of 1860-1970, with its concomitant progressive desiccation of the @ area in question, has passed over into the next aboveverage rainfall era. This does not mean that there will be no further cataclysmic droughts during future rainfall trough periods. It is therefore wise to plan ahead to meet such contingencies. The present water distribution pattern in the park (natural plus artificial water) is conspicuously still well below that which pertained, during dry seasons, at the turn of the century, when the Sabi and Shingwedzi game reserves were proclaimed. It is the declared policy of the National Parks Board of Trustees to simulate natural regulating mechanisms as closely as possible. In consequence the artificial water-for-game program is a long way from completion. The large numbers of game animals in the park (including dominant species such as elephant Loxodonta africana and buffalo Syncerus coffer) can no longer migrate out of the area to escape natural catastrophes (such as the crippling droughts of 1911-1917, the 1930s, 1940s and 1960s), and a reliable supply of artificial water in all the areas where natural supplies have dried up since 1902 should be provided, to prevent an irreversible population crash of many animal species during future periods of protracted drought. Such a catastrophe could well spell the end of the park as a viable, self-sustaining wildlife sanctuary and destroy its well-established tourist industry. Special measures will have to be taken to safeguard the perennial rivers of the park and their unique aquatic life from the calamitous effects of progressive desiccation or serious pollution.