Rapid flood inundation assessment is critical for antici- pating disruptions to transportation networks and informing evacuation planning. This study evaluates a GIS-based flood simulation workflow in ArcGIS Pro by analyzing inundations associated with the Ditwah cyclone in the accessibility near the Kaduwela interchange. The simula- tion is forced by event-based rainfall and river discharge and represents inundation as a terrain-controlled surface flooding, rather than explicitly solving the shallow-water equations. The simulated inundation extents are validated satellite-derived flood maps by using spatial overlay analy- sis and the Critical Success Index (CSI). The results show moderate skill overall (CSI of 0.38), with better agreement in higher-elevation areas, and larger discrepancies across river-dominated zones. Simulated water-level time series evacuation window before key links become impassable. during flood events.
