This map illustrates satellite-detected flood water extent along Tana River, Galole and Garsen sub counties, Tana River county, Kenya. The analysis was conducted by analyzing Sentinel-1 imagery acquired on the 4 May 2018. The analysis extent is focused on the river bed of Tana, the surrounding land between the primary road and the limit of the Tana River boundary, specifically where the population is concentrated. Within the analysis extent, around 22,700 ha of land appears to be inundated and more than 21,600 people are living inside this flood water extent. It is likely that flood waters have been systematically underestimated along highly vegetated areas along main river banks and within built-up urban areas because of the special characteristics of the satellite data used. This is a preliminary analysis and has not yet been validated in the field.