COMPARISON OF FLOOD EXTENT DETERMINATION IN THE LIMPOPO RIVER BASIN, SOUTH AFRICA USING ELEVATION DATA AND SYNTHETIC APERTURE RADAR

The Limpopo River Basin (LRB) is a transboundary watershed that spans Botswana, Mozambique, South Africa, and Zimbabwe. It is home to over 18 million people, critical agricultural areas, and iconic conservation areas. The ecosystem services of the conservation areas are vital for downstream users. Variable precipitation across the LRB can cause flooding, which is difficult to predict or model. Flood extent data is limited to population centers or observation sites in conservation areas. To contrast methods of flood extent determination, we used two methods to examine a flood in Kruger National Park, South Africa, within the LRB. First, we used digital elevation model data from the Shuttle Radar Topography Mission to extrapolate water levels from known high-water data from observation points in the park. Second, we used synthetic aperture radar (SAR) data from Sentinel-1 to determine the flood extent. The primary advantage of SAR is that the radar signal can penetrate moderate cloud cover, which is not possible with optical remote sensing. The SAR-derived flood extent could be used to develop flood risk models based on river discharge statistics. This would have implications for flood extent risk, sediment transport, aquatic habitat remodeling, and water resources management.