HEC-RAS Flood Risk Mapping for Local Creeks

ISEF Category: Environmental Engineering

Subcategory: Water Resources Management  ·  Difficulty: Advanced  ·  Setup: University Lab  ·  Time: Full Year

The Hook

A school can sit outside the flood zone on one map and inside it on another. That gap can mean the difference between a routine storm and a building that loses access, power, or both. You can test that gap with real flood models and real storm data. That makes this project feel local fast.

What Is It?

This project asks a simple question with real stakes, how much does the flood risk map change when you swap older design storms for newer ones? A design storm is a rainfall pattern engineers use to estimate flooding from rare, heavy storms. HEC-RAS is software that turns terrain, stream shape, and runoff assumptions into a flood depth map.

Think of the creek like a bathtub with a bent drain. If you pour in more water, or pour it faster, the water line rises and spreads into nearby areas. FEMA maps often reflect older assumptions, while NOAA Atlas 14 gives updated rainfall estimates for many places in the United States. Your job is to compare the two storm sets, model the water spread in 2D, and see which schools, hospitals, or other critical sites fall into newly flooded areas.

Why This Is a Good Topic

This is a strong science fair topic because you can test a real, local problem with clear numbers. You can compare two storm datasets, map flood depth, and count how many critical buildings move into risk zones. You also learn skills that matter in water resources work, like GIS, model setup, calibration, and spatial analysis. The results are easy to explain because a map tells the story fast.

Research Questions

• How does using NOAA Atlas 14 instead of FEMA design storms change the predicted flood extent along a local creek?
• What is the effect of storm return period on the number of schools and hospitals inside the modeled inundation zone?
• Does adding updated terrain data change which buildings appear newly at risk?
• To what extent do predicted flood depths differ between the FEMA-based and NOAA-based scenarios at critical facilities?
• Which creek segments show the largest increase in flood spread under updated storm inputs?
• What is the effect of upstream land cover assumptions on the modeled inundation area?

Basic Materials

• Laptop or desktop computer with enough memory to run HEC-RAS and GIS software.
• HEC-RAS software with 2D modeling capability.
• GIS software such as QGIS for mapping sites and terrain layers.
• Digital elevation model or LiDAR terrain data for the study area.
• Stream centerline, creek cross-section, or terrain boundary data for the local watershed.
• FEMA flood map layers for the study area.
• NOAA Atlas 14 precipitation data for the same region.
• List of schools, hospitals, and other critical facilities with addresses or coordinates.
• Spreadsheet software for organizing outputs and calculating differences.
• Notebook for tracking assumptions, model versions, and scenario settings.

Advanced Materials

• University-grade workstation or access to a computer lab with strong RAM and processor speed.
• HEC-RAS with hydraulic modeling support and export tools.
• ArcGIS Pro or QGIS with advanced geoprocessing tools.
• High-resolution LiDAR terrain and hydrograph or rainfall-runoff inputs.
• Local stream gauge data for calibration, if available.
• Surveyed channel geometry or field measurements for validation.
• Census or parcel data for adding exposure analysis.
• Python or R for automating comparisons and statistics.
• ImageJ or similar image analysis software for checking map outputs and overlays.
• External storage for large raster and model files.

Software & Tools

• HEC-RAS: Simulates river and floodplain hydraulics in one and two dimensions for your study area.
• QGIS: Maps flood extents, buildings, and terrain layers with free GIS tools.
• Python: Automates scenario comparison, raster cleanup, and exposure calculations.
• R: Helps test differences between storm scenarios and graph model outputs.
• PubMed: Finds review articles on flood exposure, public health, and risk mapping.

Experiment Steps

1. Define the exact creek reach, critical facilities, and flood scenarios you will compare.
2. Gather terrain, storm, and infrastructure layers, then check that they all use the same coordinate system.
3. Build one baseline model that matches the local creek geometry and drainage boundaries.
4. Create parallel storm scenarios from FEMA and NOAA Atlas 14, then keep every other model input the same.
5. Plan how you will measure change, such as flood extent, depth at buildings, and the number of sites newly exposed.
6. Design a validation check using any gauge data, photos, past flood reports, or observed high-water marks you can find.

Common Pitfalls

• Using mismatched map projections, which shifts schools or hospitals into the wrong flood zone.
• Comparing FEMA and NOAA storms without keeping the terrain and boundary conditions constant, which hides the real cause of change.
• Choosing a creek reach that is too small or too clean, which makes the model look neat but weakens the real-world story.
• Treating a flood polygon as exact without checking depth, which can overstate risk near building edges.
• Skipping validation against any local evidence, which makes the model look like a guess instead of an analysis.

What Makes This Competitive

A stronger project goes beyond making a flood map. You compare scenarios with careful controls, test how sensitive the result is to terrain or rainfall assumptions, and quantify exposure at specific buildings instead of only showing colored overlays. You can also add a tougher angle, like depth thresholds for access loss or a statistical comparison of scenario differences across the creek reach. That turns the project from a mapping exercise into a real risk analysis.

Project Variations

• Use a different local waterway, such as a tributary, urban ditch, or drainage canal, to compare how storm updates change exposure patterns.
• Replace schools and hospitals with fire stations, nursing homes, or evacuation routes to study different critical infrastructure.
• Add a climate or land-use comparison by testing whether future rainfall or new development changes the same flood risk map.

Learn More

• HEC-RAS User’s Manual: Read the official modeling guide from the US Army Corps of Engineers, usually available through the HEC website and public documentation pages.
• NOAA Atlas 14: Use NOAA precipitation frequency data and technical reports, available through NOAA’s precipitation frequency portal and documentation.
• FEMA Flood Map Service Center: Find official flood maps, map layers, and community flood information for your study area.
• USGS National Map: Download elevation data and hydrography layers for terrain and stream mapping.
• QGIS Documentation: Learn free GIS mapping workflows from the official QGIS documentation and training materials.
• Water Resources Research: Search the journal for flood modeling, design storm, and inundation mapping studies through a library database or journal site.