Flood monitoring and mapping using passive microwave remote sensing in Namibia

Space-based river monitoring can provide a systematic, global, timely and impartial way to monitor disastrous floods. This paper describes a methodology to use daily passive microwave observations to detect, map and size floods, both for the purposes of global humanitarian organizations and national hydrological services. In the best case, floods can be detected as early as 2 h after they occur. Early warning is possible by monitoring upstream areas, with warning lead times up to 30 days. Flood maps are of a low resolution but match maps derived from high-resolution imagery. The interest lies in their daily availability, allowing us to understand the dynamic aspects of floods. Finally, objective flood sizing is achieved by integrating information over time and space. This paper details the results of the technique for the 2009 floods in Southern Africa and experiences for the 2010 flood season in Namibia.