Evaluating the effectiveness of ratio-based change detection with integrating river gauge data for delineating inundated extents: a case study of the River Dee

Abstract

Ratio-based change detection has been widely applied to flood mapping large river systems, but its effectiveness in narrow, topographically diverse catchment such as the River Dee in Scotland has not been previously evaluated. This study applies ratio-based change detection to Sentinel-1 SAR imagery to delineate inundation patterns across the River Dee for three flood events (2015-16, 2019, and 2020), while integrating hydrometric data from the Scottish Environment Protection Agency (SEPA) to validate and interpret results.

The analysis resulted in several factors influencing the mapped inundation extents. By combining gauge data with satellite-derived inundation maps, this study highlights both the strengths and limitations of using ratio-based change detection in complex upland and lowland river systems.