Assessment of physical vulnerability to flooding using Geographic Information System (GIS)-based Multi-Criteria Decision Analysis (MDCA) in Lephalale Local Municipality in Limpopo, South Africa

Abstract

Floods are one of the most common recurring natural disasters globally. They impact communities by damaging natural resources, disrupting economic activities, destroying property and livelihoods, displacing people and causing loss of lives. In South Africa, predictions are that flood incidences are likely to increase due to climate change, hence placing communities at risk of floods. This study sought to assess and map the physical vulnerability of areas to flooding in the Lephalale Local Municipality using a Geographical Information System (GIS)-based Multiple Criteria Decision Analysis (MCDA) approach. Using various indicators, a composite map was developed showing the different levels of vulnerability to floods in the municipal area. Physical vulnerability to floods was found to be higher in the central regions compared to the rest of the municipal area, because of the high magnitude of the rainfall in the central region, its proximity to rivers, and the presence of impermeable bare soils that increase runoff. The north, west and southern parts of the municipal region showed moderate to low levels of vulnerability due to their slightly higher elevation, longer distances from rivers, and the presence of natural vegetation land cover. The study concluded that physical vulnerability to floods in the area was largely a result of the interaction of various factors, namely: proximity to river channels, precipitation amount, altitude, and soil type. Although the study demonstrated the usefulness of the GIS-based MCDA approach in assessing physical vulnerability to floods, we recommend that future studies also consider integrating social, economic, cultural and institutional indicators to capture the multi-scale and multi-faceted dimensions of flood vulnerability.