A review of remote sensing of flood monitoring and assessment in southern Africa

Southern Africa is one of the most vulnerable regions to flooding and this severely impacts its economic development, human livelihoods and ecosystem functioning. In this regard, there is need to identify strategies to monitor flood occurrence, to minimize effects. Remote sensing is one of the key data sources for natural hazards monitoring, over space and time. This paper therefore provides the state-of-the-art review on flood monitoring, using remote sensing in southern Africa, since the emergency of earth observation technologies. Specifically, the review focused on how southern Africa has embraced remote sensing for mapping flood extent, vulnerable areas and impacts, over time. The review also highlights available remote sensing data and products, to monitor floods, including their success, limitations, and prospects for improved flood monitoring in the region. Overall, there has been limited use of remote sensing data in flood monitoring in southern Africa, until 2010. Since then, there was an increase in the use of remote sensing data, for flood monitoring. Most of these studies used the freely available Landsat and MODIS datasets, and these studies focused more on mapping the extent of flooding. However, as much as considerable strides were made, there is still more work to be done. Future research needs to shift towards the use of new generation remote sensing data, including radar, as well as high spatial resolution drones, before, during and after flood occurrence. Advanced cloud-computing, such as Google Earth Engine and machine learning algorithms, also present opportunity for time series analysis of flooding.