Flooding is a major hazard in rural and urban areas worldwide and accounts for a large portion of life and economic losses caused by natural disasters. Non-structural measures to reduce flood damage are very economical compared to structural measures.
Accurate and rapid prediction of flood inundation extent is an important task to reduce flood risk. Non-structural measures make it possible to predict inundation areas by combining accurate flood forecast and real-time observations.
Seeded Region Growing (SRG) is widely used for flooded area extraction. The seeded region growing method requires a large amount of memory space because the entire DEM dataset is initially assigned to memory, which cannot be implemented with the existing PC’s memory space. Furthermore, the limited use of computer memory space prevents the implementation of computational continuity during flood inundation analysis. When there is a large area of inundation extent and a large amount of DEM data, many recursive operations required by the seeds region growing algorithm reduce computational efficiency and can cause stack overflow due to the large data. For this reason, the use of seeded region growing algorithm applied to flood inundation prediction is limited.
Ko Song Hwan, a researcher at the Institute of Information Technology, proposed an isosurface region growing method to reduce floodplain extraction time using high resolution DEM, and a locally detailed grid SRG method to solve the problem of different inundation area by different DEM resolutions.
On a contour map with small contour intervals, if all the intersected points on the two adjacent contour lines are submerged, it can be seen that the isosurface between those contours is completely submerged. The isosurface region growing method can reduce the time for flood inundation extent extraction more than the seeded region growing method as it extends inundation areas by isosurface along the contour tree. The locally detailed grid SRG method divides the cells intersecting with top contours of the terrain barrier into small size cells. Then, a seed point is selected on the isosurface which is not completely submerged and the seeded region growing method is applied. This method can solve the problem of distorted diffusion of inundation areas around the terrain barrier.
Comparing the inundation area extraction time by the seed area growth method with that by the contour area growth method and the detailed grid SRG method, he found that the proposed method consumes less computation time.
His paper “Flood inundation extent extraction using isosurface region growing and locally detailed grid SRG” was presented at “2025 10th International Conference on Intelligent Information Technology (ICIIT 2025)”.
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