A comprehensive review of flood inundation mapping using HEC-RAS: Advances, challenges, and future perspectives

Floods are among the most destructive natural hazards, causing severe damage to human life, infrastructure, agriculture, and the environment. Accurate flood inundation mapping is essential for effective flood risk management, emergency response, and sustainable land-use planning. The Hydrologic Engineering Center’s River Analysis System (HEC-RAS) has become one of the most widely used hydraulic modeling tools for flood inundation studies due to its accessibility, reliability, and continuous technical improvements. This review presents a comprehensive assessment of flood inundation mapping using HEC-RAS, highlighting recent advances, key challenges, and future research opportunities. The study examines the evolution of HEC-RAS from conventional one-dimensional (1D) steady-flow models to advanced two-dimensional (2D) unsteady-flow simulations capable of representing complex floodplain dynamics. Integration with Geographic Information Systems (GIS), remote sensing, LiDAR-derived Digital Elevation Models (DEMs), and climate datasets has significantly enhanced the accuracy and applicability of flood mapping. Recent developments such as real-time forecasting, coupled hydrologic-hydraulic modeling, and machine learning-assisted calibration are also reviewed. Despite these advancements, several challenges remain, including uncertainty in terrain data, boundary conditions, Manning’s roughness coefficients, computational limitations, and lack of reliable hydrological data in ungauged regions. Urban flood modeling also remains complex because of drainage systems, impervious surfaces, and rapid land-use changes. Future research should focus on high-resolution data integration, artificial intelligence for rapid prediction, IoT-based monitoring systems, and climate-resilient flood management strategies. Overall, this review highlights the growing importance of HEC-RAS as a robust decision-support tool for flood hazard assessment and provides guidance for researchers, engineers, and policymakers to improve flood resilience through advanced inundation mapping practices.