Rapid flood inundation mapping for dam failure and operations

Dam failure often causes catastrophic flooding. Although conventional hydrodynamic models are available for generating flood inundation maps, there is a need for low-complexity models that can provide rapid inundation estimates during emergency situations. Operational releases of large volumes may also lead to downstream flooding. This study utilizes two DEM-based models, OWP HAND-FIM and FLDPLN, to produce flood inundation maps for near-real-time operational applications. Three dam-related scenarios, including failures and controlled operations, are examined using these simplified models for the Fall River Dam in Kansas. Breach flows are estimated using empirical relationships, and discharge attenuation is calculated using an analytical approach. The resulting inundation maps are evaluated against HEC-RAS simulations. Model performance is assessed based on the predicted flood extent and its impact on buildings. The results demonstrate satisfactory agreement with the HEC-RAS outputs, yielding average accuracy values of 0.92 for OWP HAND-FIM and 0.94 for FLDPLN in identifying inundation extents. The proposed flood mapping technique is also tested for an actual dam-break flood. The terrain-based approach provides a considerable operational advantage over hydrodynamic simulations of dam-breach flooding in real-time by reducing run-time by a factor of more than 1000. • Flood inundation maps were developed using low-complexity DEM-based models for dam-related floods. • High accuracy in identifying dam-break flood extents compared with HEC-RAS model. • Significant reduction in computation time for emergency planning and management.