Modeling the Effects of Sea-Level Rise on Flooding in the Lower Ozama River Basin, Santo Domingo, Dominican Republic

Sea-level rise (SLR) and extreme precipitation increasingly threaten low-lying tropical cities, yet flood assessments in the Dominican Republic have relied primarily on static, elevation-based approaches. This study develops a multi-model framework to evaluate the impacts of SLR and compound fluvial and tidal interactions on flooding in the lower Ozama River Basin, Santo Domingo. A one-dimensional (1D) HEC-RAS model was reconstructed from Belliard (2020) with newly incorporated bathymetric data, while a two-dimensional (2D) unsteady flow HEC-RAS model and a static bathtub model were used to simulate present and future inundation scenarios. The 1D simulations showed that including bathymetry increased hydraulic accuracy and produced larger flood extents for higher return period events. The 2D model captured spatial and temporal flood dynamics across SLR scenarios of 0.30–1.00 m and in compound configurations combining SLR with 25-, 50-, and 100-year discharges. Compared with the bathtub model, which predicted 1.97 km² of inundation, the 2D simulations yielded 0.52 km² for equivalent SLR levels, indicating that static methods overestimate flood area by neglecting flow connectivity and backwater effects. Compound scenarios produced the most extensive and prolonged flooding, confirming that interactions between river discharge, tides, and SLR amplify inundation nonlinearly. Results identify Domingo Savio, Los Tres Brazos, and Los Guandules as the most flood-prone neighborhoods and highlight the need for dynamic hydraulic modeling in urban adaptation planning. The framework developed here provides a physically consistent basis for improving flood risk mapping and advancing scientific understanding of coastal and riverine flooding in the Dominican Republic.