As remote sensing technologies for environmental and hydrological applications have been unprecedentedly increasing, the use of microwave remote sensing (rather than optical remote sensing) for land and hydrological monitoring becomes very known. The microwave sensor, Synthetic Aperture Radar (SAR) is one of the microwave sensors for near real time flood detection and mapping. This thesis work applies the microwave sensor, Sentinel-1A SAR time series images to detect and map the incident of flood event, taking a case study on Lake Koka catchment of Awash River basin, Ethiopia. The work hopefully provides the way how to process and analyze the SAR image for flood detection. It shows methods for detail technical and procedural work-flows for SAR imagery based on the context of flood detection and mapping.