Drone Mapping Gully Erosion Over Time

ISEF Category: Environmental Engineering

Subcategory: Land Reclamation  ·  Difficulty: Advanced  ·  Setup: School Lab  ·  Time: Full Year

The Hook

A gully can grow fast enough to eat into a field or park in one school year. That means a small channel can become a real land-loss problem before anyone notices. You can measure that change with drone photos, then turn the images into a 3D terrain model. The result is a project that connects cameras, maps, and soil loss.

What Is It?

This project asks you to measure how a gully changes over time. A gully is a small but deep channel cut by running water. When rain washes soil downhill, the ground surface drops in some places and stays the same in others. You can capture that shape with drone photos and turn the images into a digital elevation model, or DEM, which is a height map of the land.

Think of it like making a topographic version of a before-and-after photo. One model shows the surface at one point in time, and another shows it later. If you subtract one DEM from the other, you can estimate where soil was lost or deposited. That process is called DEM differencing. It gives you a measurable number for erosion instead of just a visual guess.

Open Drone Map is open-source software that helps convert overlapping aerial photos into maps and elevation models. With careful flight planning, ground control points, and repeat surveys, you can track how the gully changes across a school year. This turns a local land problem into a data project you can analyze with real spatial measurements.

Why This Is a Good Topic

This is a strong science fair topic because you can measure a real environmental process over time. Erosion is easy to spot, but hard to quantify well. Your project lets you test whether a site is losing soil, where the worst change happens, and how much the shape shifts after storms or seasons. You can also learn geospatial analysis, photogrammetry, and change detection, which are useful skills in environmental engineering.

Research Questions

• How does gully depth change between the start and end of the school year?
• What is the effect of rainfall exposure on the measured volume of soil loss in a monitored gully?
• Does the gully headcut migrate farther upstream in wetter months?
• To what extent do slope position and vegetation cover predict where the largest elevation drop occurs?
• Which parts of the gully show the most change when comparing DEMs from different survey dates?
• How does the measured erosion differ between the gully centerline and the gully edges?

Basic Materials

• Drone with a stabilized camera or a phone-mounted aerial platform.
• Smartphone with GPS and a high-resolution camera.
• Laptop with Open Drone Map or similar photogrammetry software.
• Measuring tape or survey rope.
• Ground control point targets made from printed markers or painted boards.
• Handheld GPS unit or smartphone GPS app.
• Clipboard or field notebook.
• Weather and rainfall records from a local station or NOAA.

Advanced Materials

• Drone with RTK or PPK capability.
• Survey-grade ground control points.
• Total station or differential GPS for control point surveying.
• Reference markers for accurate alignment between surveys.
• University computer with enough RAM and storage for photogrammetry processing.
• GIS software for DEM differencing and spatial analysis.
• ImageJ or similar tool for quick image comparison checks.
• Statistical software for uncertainty analysis.

Software & Tools

• OpenDroneMap: Builds orthomosaics and DEMs from overlapping drone images for terrain comparison.
• QGIS: Aligns, clips, and compares elevation rasters for change detection.
• ImageJ: Checks image sharpness, contrast, and consistency before processing.
• R or Python: Analyzes elevation change, summarizes volume loss, and graphs trends over time.
• NOAA Climate Data Online: Provides local rainfall data for linking erosion change to weather.

Experiment Steps

1. Define the gully boundary and decide how you will mark the same area at every survey.
2. Choose ground control points and a repeatable flight path so each mapping session lines up well.
3. Plan a baseline survey that produces a clean DEM you can compare against later surveys.
4. Decide which environmental variables you will track alongside erosion, such as rainfall, vegetation, or slope.
5. Build a change-detection workflow that subtracts later DEMs from the baseline and converts height change into volume change.
6. Set a method for checking error, so you can tell real erosion apart from mapping noise.

Common Pitfalls

• Flying at inconsistent heights or angles between surveys, which breaks alignment and makes DEM differencing noisy.
• Skipping ground control points, which can make the map shift enough to hide real soil loss.
• Measuring after major vegetation growth, which can block the ground surface and distort elevation models.
• Using different lighting or shadow-heavy conditions, which can create bad image matching and weak reconstruction.
• Comparing maps without checking error bounds, which can make small elevation changes look more certain than they are.

What Makes This Competitive

A stronger project goes beyond making a pretty map. You should quantify uncertainty, compare multiple survey dates, and relate erosion change to rainfall or site conditions. You can also test whether one part of the gully changes faster than another, or whether vegetation slows the loss. Clear controls, repeat surveys, and careful statistics make the work much stronger.

Project Variations

• Compare a grassy gully, a bare-soil gully, and a mulched site to see how ground cover changes erosion rates.
• Use a phone camera and a drone camera on the same site to compare mapping quality and measurement error.
• Track one gully after major storms, then compare those changes with a second site that drains more slowly.

Learn More

• Open Drone Map Documentation: Learn the workflow for building orthomosaics and DEMs from aerial photos, then find the docs through the Open Drone Map project site.
• USGS National Map: Find elevation data, map layers, and terrain resources through the U.S. Geological Survey mapping portal.
• NOAA Climate Data Online: Search local rainfall and storm records to connect erosion change with weather patterns.
• NASA Earthdata: Explore free remote sensing and land-surface resources through NASA Earthdata search tools.
• QGIS Training Materials: Use the free QGIS documentation and tutorials to learn raster alignment, clipping, and DEM differencing.