South Africa is already hydrologically vulnerable and this is likely to be exacerbated by both nonpermanent ENSO-related as well as more permanently greenhouse-gas forced climate changes. Climate change effects are explained by way of the hydrological equation. This serves as a backdrop to a brief review, in a hydrological context, of projected perturbations to temperature, rainfall and potential evaporation, over southern Africa. Methodologies for simulating hydro logical responses to climate change are assessed. These include more direct GCM-derived output, with some emphasis on recent advances in climatic downscaling, and the application of appro priate hydrological models for use in impact studies. Scale problems of importance to hydrologists are highlighted. Directions to which climate change-related hydrological research efforts should be expended in South Africa are summarized, before two case study simulations, one a general sensitivity study of hydrological responses to changes in rainfall over southern Africa, the other a more specific hydrological response study to the El Niño of the 1982-83 season, are presented. The article concludes with a discussion on whether or not water resources practitioners in South Africa should respond to climate change.
Bass, B.1993: Summary report on IGBP/BAHC workshop on Focus 4: the Weather Generator Project. Berlin: IGBP-BAHC Core Project Office, Department of Meteorology, Free University, Berlin.
2.
Belachew, A.B.1996: Filtering the effect of orography from moisture recycling patterns. MSc thesis, International Institute for Infrastructural, Hydraulic andEnvironmental Engineering, Delft.
3.
Beran, M.1989: Hydrological impacts - what if we are right? In Berger, A., Schneider, S.H. and Duplessy, J.C., editors, Climate and geo-sciences: a challenge for society in the 21st century. NATO ASI Series C: Mathematical and Physical Sciences285, 661-65.
4.
Body, D.N.1991: Water sciences at the threshold of the 21st century: are we preparing sufficiently for the global change likely to occur? In: Proceedings of the IHP symposium on 25 years of IHD/IHP , Paris: UNESCO, 147-57.
5.
Da Cunha, L.V.1989: Climate changes and water resources development . In Berger, A., Schneider, S.H. and Duplessy, J.C., editors, Climate and geo-sciences: a challenge for society in the 21st century. NATO ASI Series C: Mathematical and Physical Sciences285, 639-57.
6.
Fowler, A.M. and Hennessey, K.J.1995: Potential impacts of global warming on the frequency and magnitude of heavy precipitation. Natural Hazards11, 283-303.
7.
Hewitson, B.C. and Crane, R.G.1994: Neural nets: looks and uses. In Hewitson, B.C. and Crane, R.G., editors, Neural nets: applications in geography, Dordrecht: Kluwer Academic.
8.
— 1996: Climate downscaling: techniques and application, Climate Change, in press.
9.
Hewitson, B.C. and Main, J.L.P.1996: Regional climate change scenarios for precipitation and temperature from GCMs. Interim report. Pretoria: Water Research Commission.
10.
Hulme, M., editor, 1996: Climate change and southern Africa: an exploration of some potential impacts and implications in the SADC region. Norwich: Climate Research Unit, University of East Anglia.
11.
Intergovernmental Panel on Climate Change (IPCC)1992: 1992 IPCC supplement: scientific assessment of climatic change. Report prepared by Working Group I, WMO-UNEP. ( Houghton, J.T., Callander, B.A. and Varney, S., editors). Cambridge University Press.
12.
— 1995: Climate change 1995: impacts, adaptations, and mitigation. Summary for policymakers. Geneva: WMO/UNEP.
13.
Jones, P.D.1994: Hemispheric surface air temperature variability - a reanalysis and an update to 1993. Journal of Climate7, 1794-802.
14.
Joubert, A.M.1995: Simulations of southern African climate by early generation general circulation models. South AfricanJournal of Science91, 85-91.
15.
Joubert, A.M. and Hewitson, B.C.1997: Simulating present and future climates of southern Africa using general circulation models. Progress in PhysicalGeography21, 51-78 (this issue).
16.
Joubert, A.M. and Tyson, P.D.1996: Equilibrium and coupled GCM simulations of future southern African climates. South AfricanJournal of Science92, 471-84.
17.
König, W., Sausen, R. and Sielmann, F.1993: Objective identification of cyclones in GCM simulations . Journal of Climate6, 2217-31.
18.
Kulshreshtha, S.N.1993: World water resources and regional vulnerability: impact of future changes. IIASA Research Report 93-30. Laxemburg , Austria: IIASA.
19.
Kundzewicz, Z. and Somlody, L.1993: Climate change impact on water resources - a systems view . IIASA Working Paper 93-30. Laxemburg, Austria: IIASA.
20.
Kunz, R.P. and Schulze, R.E.1993: A sensitivity analysis of runoff production in southern Africa to global climate change. In: Proceedings, sixth South African national hydrological symposium, Pietermaritzburg : University of Natal, Department of Agricultural Engineering , 203-10.
21.
Loaiciga, H.A., Valdes, J.B., Vogel, R., Garvey, J. and Schwarz, H.1996: Global warming and the hydrologic cycle. Journal of Hydrology174, 83-127.
22.
Mason, S.J., Joubert, A.M., Cosijn, C. and Crimp, S.J.1996: Review of seasonal forecasting techniques and their applicability to southern Africa. Water SA22, 203-208.
23.
Murphy, J.M. and Mitchell, J.F.B.1995: Transient response of the Hadley Centre coupled ocean-atmosphere model to increasing carbon dioxide. Part 2. Spatial and temporal structure of the response. Journal of Climate8, 57-80.
24.
Nemec, J.1995: General circulation models, climate change, scaling and hydrology. In Kite, G.W., editor, Time and the river, Highlands Ranch, CO: Water Resources Publications, 317-56.
25.
Parry, M.L., Carter, T.R. and Hulme, M.1996: What is dangerous climate change?Global Environmental Change6, 1-6.
26.
Penman, H.L.1948: Natural evaporation from open water, bare soil and grass . Proceedings of the Royal Society ( London ) A193, 120-46.
27.
Pittock, A.B.1991: Developing regional climate change scenarios: their reliability and seriousness. Hawkesbury Centenary Conference , University of Western Sydney, 25-27 November (Mimeograph).
28.
Schulze, R.E.1990: Climate change and hydrological response in southern Africa: heading towards the future. South AfricanJournal of Science86, 373-81.
29.
— 1991: Global climate change and hydrological response: a southern African perspective. In Proceedings, fifth South African national hydrological symposium, Cape Town: NSI, 1-1 to 1-17.
30.
— 1993: Downscaling from global to mesoscale: an approach to assessing hydrological impacts of climate change in southern Africa. Presentation to a workshop on scale issues in hydrology/environmental modelling, Robertson, Australia.
31.
— 1995: Hydrology and agrohydrology. Water Research Commission Report TT 69/95. Pretoria: Water Research Commission.
32.
Vorosmarty, C.J., Gutowsky, W.J., Perron, M., Chen, T.C. and Chase, D.1993: Linked atmosphere-hydrology models at the macroscale . In Wilkinson, W.B., editor, Macroscale modelling of the atmosphere. IASH Publication 214, Wallingford : IASH, 3-27.
33.
Whitmore, J.S.1971: South Africa's water budget. South AfricanJournal of Science67, 166-76.
