Mapping embankments and merlons in the Upper Seine River basin : A GIS-based approach for comprehensive floodplain dynamics.

There is currently no pre-existing map of embankments, dikes, levees and merlons in the Upper Seine River basin as existing data is limited to specific local studies. Developing a comprehensive map of these features is needed for effective flood risk management and planning. Embankments and merlons play a significant role in shaping the basin’s hydrological and geomorphological dynamics, influencing water flow patterns, floodplain connectivity, and sediment transport. Accurate mapping enables authorities to identify areas where these structures may exacerbate flood risks or disrupt natural floodplain functions, which are essential for mitigating flood impacts. Leveraging advancements made in GIS and LiDAR DEM data, an automated tool was developed to detect and map these features within the floodplain. Their detection was made possible by extracting morphometric parameters related to relative height, slope, and convexity. The mapped features were then characterized to evaluate their potential impact on flood dynamics. This characterization considers three parameters: the valley’s width, the embankment’s position within the valley and its elevation. The tool demonstrates encouraging outcomes, with good detection accuracy and a characterization protocol consistent with field observations. These findings establish a scalable methodology that can be applied to geomorphologically similar regions, providing a framework for improved floodplain management.