Plan for the new norm to secure water
WORLD Meteorological Day is observed every year on March 23 and commemorates the 1950 Convention that established the World Meteorological Organisation.
It showcases the essential contribution of National Meteorological and Hydrological Services to the safety and well-being of society.
The theme this year is “The Sun, the Earth and the Weather”. It is based on the premise that the sun delivers the energy that powers all life on Earth and drives the weather, ocean currents and the hydrological cycle.
The Water Research Commission (WRC) hosts a climate change flagship programme that funds various research and development partners to conduct research on aspects of weather and climate as it affects development, particularly for the water-linked sectors. Water is a critical determinant for development, economic growth and a better life. Its availability depends on the weather and climate.
Most rainfall comes from the condensation of water vapour originating from the flux of moisture from ocean to atmosphere, but the temperature of the remote and surrounding oceans has an impact on the inter-annual variability of rainfall.
Little work has been done to connect stream flow to the El Niño southern oscillation. A recently completed WRC study, led by Professor Mathieu Rouault of UCT, looked at the tropical Atlantic Ocean, which is closer to South Africa but smaller, where a phenomenon similar to El Niño occurs, the Benguela Niño.
Closer to South Africa, the Agulhas current was known to affect the atmosphere above it due to a high turbulent flux of moisture from sea to atmosphere. In this case, the results showed analyses of atmospheric dynamics associated with global ocean-atmosphere modes of variability which influence vital southern African rainfall.
It is also important to consider that, at the regional scale, anthropogenic climate change signals will be strongly modulated by natural climate variations, which are likely to induce variations at the decadal time scales.
Tropical weather systems invade the northern parts of South Africa in the late summer months and are often associated with heavy rainfall and flooding. Tropical disturbances peak between December and February.
Due to the high frequency of heavy rainfall events in summer over the eastern and north-eastern parts, it is important to develop better forecasting techniques.
Of note is that the 2015/16 El Niño and associated drought brought water restrictions to Gauteng, given that it was the third season of below-normal rainfall over eastern South Africa. A water crisis was looming, but good rains in the late summer of 2016/17, which occurred in association with a La Niña event, broke the drought.
Nevertheless, this demonstrated South Africa’s vulnerability to multi-year drought in the mega-dam region. Drastic increases in temperature are likely to lead to increased evaporation in the mega-dams and drastic reductions in soil moisture.
These assessments and future projections advocate planning that considers a future climate while adapting to the new norm, which is characterised by extreme weather events. It is important to plan adequately to respond to both droughts and floods while increasing resilience. This will reduce societal vulnerability while encouraging sustainable development.