Mapping risk of levee overtopping using LiDAR data: A case study in Nakdong River Basins, South Korea

Overtopping occurs when the flood water’s level is greater than the levee’s height. Mapping risk of levee overtopping is efficient for assessing levee stability, generating flood hazard maps and planning flooding management. This paper proposes a methodology for mapping the risk of levee overtopping using the topographic Light Detection and Ranging (LiDAR) data taken in Nakdong River Basins, South Korea. The procedure is as follows: A slope map is generated from the LiDAR data, then the levee crown polygons and the riverside levee boundaries are extracted from the slope map by using the levee crown detection method. The levee crown segments with the risk of overtopping are identified using the values of the average height of the levee crown polygon, the designed flood level, and the freeboard. Next, different-colored levee boundaries are generated to show the risk of overtopping on each levee crown segment. Finally, the areas with the height lower than the designed flood level are shown on the levee crown surfaces as the red points. In this research, the risk of overtopping on the two levees (Jungsan Levee and Daesan Levee) parallel to the Nakdong River’s mainstream are assessed by using the proposed methodology. This research shows that Jungsan Levee do not have the risk of overtopping, while Daesan Levee has the risk of overtopping.