H&H Engineer II Waggoner Engineering Inc., Alabama, United States
Abstract Submission: Flooding presents a severe environmental risk that demands effective and affordable solutions for both analysis and mitigation efforts. The cost of traditional physical models, 3D models for scenario analysis, or inaction against floods can be enormous. Therefore, this study explores the utility of terrain modification within HEC-RAS (a widely used open-source hydraulic modeling software) to evaluate different flood mitigation strategies in the City of Canton. As two-dimensional (2D) hydraulic modeling gains popularity in flood analysis, this research leverages a calibrated HEC-RAS model to examine how changes to the terrain—such as building floodwalls, enlarging culverts and bridges, modifying channels, or restoring floodplains—can influence flood reduction. By simulating a 100-year, 24-hour storm event and comparing the results to FEMA benchmarks, the study analyzes the impacts of these modifications on water surface elevations and flood extents. The findings show that terrain modifications can represent structural interventions, with some scenarios lowering flood levels by as much as 3 feet, significantly reducing the overall extent of flooding and alleviating backwater impacts on tributaries. This suggests that terrain modification tools, combined with economic feasibility studies, can offer an effective early-stage framework for assessing flood mitigation strategies. While Digital Elevation Models (DEMs) provide useful data, they may not fully capture the intricacies of natural terrain. Therefore the ability to modify terrain within hydraulic models also marks a significant advancement in simulation accuracy. Additionally, this study highlights the value of terrain manipulation in HEC-RAS as a flexible and cost-efficient method for testing flood reduction alternatives. This enables communities to assess potential solutions and make informed decisions to enhance resilience. Policymakers can use this approach as a foundational tool for evaluating risks, exploring mitigation options, performing cost-benefit analyses, and raising awareness among stakeholders.
Learning Objectives/Expected Outcome (Optional) : 1. Learn about the HEC-RAS' capability of terrain modification allows us to test different what-if scenarios for flood mitigation 2. Learn how alteration of the landscape can impact the flow characteristics such as water surface elevation, inundation extent, and velocity. 3. Learn how the tools can help communities visualize various scenarios and make an informed decision.
