Flash flood risk management in a South African township: a case study of Alexandra

Abstract

Several studies have been carried out on improvement of flood risk assessment and management in South Africa. Despite all these studies, the problem of F lash Flood (FF) persists. This study was designed to determine the most appropriate Flash Flood Inundation Model that could be applied in flash flood risks management in a South Africa Township: a case study of Alexandra. Alexandra Township being a FF prone area was chosen for this study from where a sample of 30 respondents was purposively selected. A survey (Questionnaire) and document search were used to collect relevant quantitative data and qualitatively based secondary information from the sample population respectively. Also, data were collected through in-depth interviews of senior officials in the Disaster Management Services for more well-rounded information. Content analytical method was used to process the qualitative information. The study adopted complementary analytical tools, namely, R-programming and appropriately selected tools from the Statistical Package for Social Sciences (SPSS version 21.0) to analyze the quantitative data and to determine the most appropriate Flash Flood Inundation Model. In search of mitigating the risk of the FF in Alexandra Township, a FF inundation model was determined. People were educated on FF not to build shacks along Juskei River and were trained to prepare for and manage FF. Early Warning messages were sent and community volunteers were trained on managing risks related to FF. The main observed risk factors of FF where building of shacks without abiding by the rules and regulation, blocking of drainage system by illegal dumping of solid waste and growth in population. The major risk factors the respondents agreed to cause FF where annual rainfall intensity (70.0%), poor drainage (56.7%) and human settlement (50.0%). The three Principal Components identified to be contributing to FF in Alexandra Township were terrain, soil texture and poor drainage system. This factors contributed 82.0% of FF risk factors in Alexandra Township. The model revealed that appropriate solid waste disposal, construction of sewers, dredging of Jukskei River, and construction of Gabions along Jukskei River will mitigate flash flood risk and related hazards in Alexandra Township.