|
|
Vulnerability to change usually includes identifying both the external (hazard) factors shaping vulnerability and the internal (coping or susceptibility) factors shaping coping capacity. One also needs to be very clear about what one is measuring: vulnerability and risk to what?
In this study, the REVAMP research group will collaborate with other consultants working for the City of Johannesburg to begin to develop a risk and vulnerability assessment for the City. The risk or hazard that will form the focus of this component of the study is flooding and extreme rainfall events. Ideally, the communities impacted should also be included in the study (e.g. their perception of risks and coping capacities), but time may not permit this to be done.
The study will be divided into three components:
- Firstly, some background details and data on local hydrology, wetland status and flooding are to be provided, with consultants already engaged in this part of the research. These data will provide a 'baseline' on which to base further assessments.
- Assessment of extreme rainfall events in Johannesburg: physical and social perspectives.
- Identification of implications for adaptation strategies and plans that will be provided, building on the adaptation planning that is currently ongoing in the City.
The following provides some background to component 2 of the study:
In February 2009 a series of intense thunderstorms passed though Johannesburg. One storm in particular wreaked havoc in Soweto. Houses and roads were flooded, bridges and cars washed away and three people died in the flooding (Mail & Guardian, 17 Feb 2009). The question that remains is whether the recent extreme rainfall events are within the cyclic oscillation of rainfall variability; or if they fall outside of this range (Tyson et al, 1975). Moreover, the links between climate variability and climate change remain an area of keen debate (e.g. IPCC, 2007). There is still uncertainty in the modelling of climate change that frustrates efforts to better enable coping and effective risk reduction measures to possible future extreme rainfall.
The aim of this component of the research is to examine retrospectively convective storms in Johannesburg from 1960-2008. In light of the uncertainty regarding forecasting models, the trends found in the frequency of convective storms might be the most useful tool to project a likely situation for the future.
Extreme rainfall events can have severe consequences for socio-economic as well as natural systems (CCSP, 2008b). It is necessary to have a thorough understanding of the risks (in this case thunderstorms) facing a community, now and into the future, to create an appropriate risk response (Vogel et al, 2008).
The specific aims of this component will thus include:
- To investigate and identify any possible patterns and trends in frequency and magnitude of convective thunderstorms in Johannesburg. Rainfall. Weather data has been obtained from the South African Weather Service (SAWS) and these will be analysed in order to identify thunderstorms in the month of December for the period of 1960-2008. A frequency analysis of storms will be done within this time frame in search of any trends or patterns (better understanding of the hazard).
- To compare the thunderstorm results with the SAWS CAELUM database of major storms which have been newsworthy, as well as to Munich Re insurance loss data. This step will help verify the identified storms and give an indication of their intensity and effect (some understanding of the impacts).
- To assess the City's response/ coping strategies as well as risk reduction and management approaches to extreme rainfall events and their consequences (better understanding of the internal/ coping response strategies). This will include, where possible, working with sectors in the City, including the Johannesburg Road Agency, stormwater engineers, etc.
By Prof Coleen Vogel
References can be provided if required.
|
|
