Floodline Delineation for Brandfort Area of South Africa: An Integrated Approach

Abstract

Floodline estimation was approached from an integrated developmental view-point in this study. The objective was to determine areas prone to flooding. This was done to serve as an early warning mechanism to support planning and development. The paper estimates the design flood with various return periods for the sub-catchment. Investigations integrated together to derive the floodline areas were the geographical information system (GIS), extraction of catchment properties from Google earth maps, digital elevation models (DEM), modelling using hydrological engineering center and river analysis system (HEC RAS). Delineated catchment parameters show that the Brandfort sub-catchment area covers 48.63 km², while the channel length is 7.124 km. The channel slope is 0.489% indicating a flat and flood-prone region. 1:50 years and 1:100 years floodline modelling shows that larger areas of the catchment have the potential of being flooded. The significance of the study suggests that by using an integrated approach, floodline delineation can serve as an early warning tool for proper flood management in order to prevent future disasters.