The City of Johannesburg is on the verge of completing its Climate Action Plan (CAP).
The plan recognises the key climate change hazards such as flooding and extreme heat identified in the 2018 adaptation plan and its suggested actions.
These will be solidified in the final CAP document that will be completed in the last quarter of 2020.
The plan seeks to mitigate the after effects of the summer rainfall season whose onset can happen as early as September and cease in March, which presents a possibility of flooding in the city of Johannesburg.
Flooding in the city has tended to happen during the December to February period. This flooding often happens following sudden and violent afternoon thunderstorms that are accompanied by hail and heavy lightning. During these storms tornadoes can also occur. Sometimes, as was the case in the recent 7-8 Feb 2020 flooding, persistent rainfall can intensify late at night or in the morning.
The extreme rainfall that fell in the city between 7-9 Feb 2020, leading to flooding in many areas was associated with the presence of tropical moisture. Tropical moisture is known to make intrusions in the sub-tropics that include the interior of South Africa from the North West province extending up to the coast of KwaZulu Natal.
This moisture is usually in the form of cloud bands, and these were found to be among the major rain bearing systems in South Africa during summer months (Hart et al, 2013). These cloud bands according to Hart and fellow authors can also be associated with heavy rainfall events.
Rainfall totals in excess of over 100mm measured over 24 hours were observed in various rainfall stations dotted across the city (see Figure 1). Usually, warnings are issued by the South African Weather Service (SAWS) when 50mm of rainfall are likely to occur (and in this case SAWS issued warnings on Friday, 6 Feb 2020).
Therefore, rainfall in excess of over 100mm can be considered severe. Similar to the 2010 flooding event that affected Coka and Mtipa streets in Soweto, this event dumped significant rainfall in the middle of the night. This would have given communities little or no time to assess the danger of flooding and therefore evacuate on time.
Figure 1. 7-8 Feb 2020 Rainfall totals. Source: Marieke de Groen communication 11Feb 2020.
This flooding wreaked havoc in the city with many low-lying roads inundated, stormwater overflowing, trees falling on roads. Two fatalities were reported. These were drowning cases: a child of about 8 years old and an adult. It must be noted as well that at the time of writing, the body of the adult who drowned has not yet been recovered, however the search is still ongoing.
The recently amended Disaster Management Act of 2015 included specific requirements for all spheres to address climate change adaptation. The Act states that municipalities must “provide measures and indicate how [they] will invest in disaster risk reduction and climate change adaptation, including ecosystem and community-based adaptation approaches".
In the city, the Environment and Infrastructure Services Department (EISD) has been entrusted with the responsibility of championing climate change action planning. As recent at December 2018, EISD concluded the review of the city's climate change adaptation plan. This plan reconfirmed that hazards such as floods and heat waves pose a risk to the city's infrastructure and human lives.
1. Hart, N.C., Reason, C.J. and Fauchereau, N., 2013. Cloud bands over southern Africa: seasonality, contribution to rainfall variability and modulation by the MJO. Climate dynamics, 41(5-6), pp.1199-1212.