Science · 6th Grade · Human Impact and Engineering · Weeks 28-36

Engineering for Flood and Landslide Mitigation

Students design and test systems to reduce the impact of floods and landslides.

• Common Core State Standards
• MS-ESS3-2
• MS-ETS1-2

About This Topic

Flood damage costs the United States roughly $8 billion per year, and communities from coastal Louisiana to mountain towns in Colorado are actively designing and rebuilding infrastructure to reduce that toll. This topic asks students to move from analysis to design: given the science of how floods and landslides work, what engineered systems can reduce their impact? Students investigate solutions including levees, retention ponds, permeable pavement, bioswales, terracing, and retaining walls , each of which addresses the problem differently and carries different trade-offs.

Aligned with MS-ESS3-2 and MS-ETS1-2, this topic emphasizes the full engineering design process: defining the problem, specifying criteria and constraints, building and testing prototypes, and iterating based on failure analysis. Students learn that effective mitigation must account for cost, available materials, land ownership, downstream effects, and community context , no single solution works everywhere or for all hazard conditions.

Active design-and-test cycles are the natural fit for this topic. Students learn more from watching their prototype drainage system fail and asking why than from reading about it, and iterative redesign reinforces the central insight that engineering is a process, not a product.

Key Questions

1. Design technologies that can help us predict and prepare for floods.
2. Evaluate the effectiveness of different flood control measures.
3. Justify the selection of specific materials for a landslide prevention structure.

Learning Objectives

• Design a model system to mitigate the impact of simulated flooding based on specified criteria and constraints.
• Evaluate the effectiveness of different flood control measures, such as levees and permeable pavement, using quantitative data.
• Compare and contrast the advantages and disadvantages of at least two different landslide mitigation strategies.
• Justify the selection of specific materials for a landslide prevention structure, considering properties like strength and permeability.
• Explain the scientific principles behind flood formation and landslide triggers relevant to engineering solutions.

Before You Start

Forces and Motion

Why: Understanding concepts like gravity, friction, and pressure is foundational for explaining how landslides occur and how mitigation structures work.

Water Cycle and Weather Patterns

Why: Knowledge of precipitation, runoff, and the factors influencing extreme weather events is necessary to understand flood causes.

Properties of Matter

Why: Understanding material properties like strength, permeability, and density is crucial for selecting appropriate materials for engineering solutions.

Key Vocabulary

Levee	An embankment, usually made of earth, built alongside a river or stream to prevent flooding of the adjacent land.
Permeable Pavement	A type of pavement that allows water to pass through it into the ground below, reducing surface runoff and helping to recharge groundwater.
Bioswale	A vegetated channel designed to slow down, absorb, and filter stormwater runoff, often used in urban areas.
Retaining Wall	A structure designed to hold back soil or rock, preventing landslides or erosion on sloped terrain.
Runoff	The flow of water over the land surface, which can increase during heavy rainfall or snowmelt and contribute to flooding.

Watch Out for These Misconceptions

Common Misconception

A bigger or taller levee always provides better flood protection.

What to Teach Instead

Levees create a false sense of security and, when they fail, often cause more catastrophic damage than if no levee existed , because development has densified in the protected area. The US Army Corps of Engineers cites this dynamic as a primary reason the 2005 New Orleans flooding was so severe. Students benefit from analyzing levee failure case studies alongside success cases to understand the risk-risk trade-off involved in levee construction.

Common Misconception

Good flood mitigation engineering is about stopping water completely.

What to Teach Instead

Effective flood mitigation is about slowing, storing, filtering, and redirecting water , not eliminating it. Trying to stop all flow completely tends to concentrate force and fail catastrophically. Students who run multiple design-test iterations in the lab often arrive at this insight themselves when they discover that distributed infiltration systems consistently outperform solid barriers on the same test.

Active Learning Ideas

Design Lab: Model Flood Control System

Student teams receive a tray with soil formed into a landscape with a marked 'town' at the base of a slope. They design and build a flood mitigation system using available materials (gravel, sponge strips, clay, cardboard) and test it by pouring a measured amount of water at the top of the slope. Teams measure how much water reached the town, analyze their failure points, and complete at least one redesign cycle before presenting their final system.

55 min·Small Groups

Collaborative Analysis: FEMA Flood Zone Maps

Students examine real FEMA National Flood Hazard Layer maps for a US city available on the FEMA Map Service Center and categorize key areas by flood risk zone. Groups identify which critical infrastructure , schools, hospitals, bridges , sits in high-risk zones and propose one evidence-supported engineered mitigation measure per site, explaining why they chose that approach over alternatives.

40 min·Small Groups

Think-Pair-Share: Bioswale or Levee?

Present students with two mitigation options for a neighborhood prone to flash flooding: a network of bioswales (moderate initial cost, ongoing maintenance, ecological co-benefits) versus a concrete levee (high initial cost, periodic maintenance, no ecological benefit). Pairs evaluate trade-offs using a provided cost and effectiveness table, then share their reasoning. The discussion surfaces how both cost structures and community values shape engineering choices.

20 min·Pairs

Real-World Connections

• Civil engineers in New Orleans use their knowledge of hydrology and structural design to maintain and improve the city's extensive levee system, protecting it from storm surges and hurricanes.
• Urban planners in cities like Portland, Oregon, incorporate bioswales and permeable pavement into street and parking lot designs to manage stormwater, reduce localized flooding, and improve water quality.
• Geotechnical engineers assess the stability of hillsides and design retaining walls and other stabilization structures for highway construction projects in mountainous regions like Colorado to prevent landslides.

Assessment Ideas

Quick Check

Provide students with a diagram of a neighborhood prone to flooding. Ask them to identify at least two potential areas for flood mitigation and sketch a simple engineered solution for each, labeling key components.

Discussion Prompt

Pose the question: 'If you had to choose between building a large levee or implementing widespread permeable pavement for a town, what factors would you consider to make your decision?' Facilitate a class discussion where students justify their choices based on cost, environmental impact, and effectiveness.

Peer Assessment

Students build simple models of landslide prevention structures using materials like clay, sand, and small rocks. After testing their models with water, they swap with a partner and use a checklist to evaluate: Did the structure hold? What material seemed most effective? What could be improved?

Frequently Asked Questions

What engineering solutions are used to prevent flooding in US cities?

US cities use a combination of gray infrastructure (levees, floodwalls, underground storage tunnels, stormwater pumping stations) and green infrastructure (bioswales, retention ponds, permeable pavement, wetland restoration). Major cities including Chicago, Houston, and Philadelphia have invested heavily in underground retention systems. The trend in modern flood management is toward hybrid approaches that combine structural protection with nature-based infiltration.

How does permeable pavement reduce flood risk?

Permeable pavement allows rainwater to infiltrate through the surface into a gravel layer below, where it either soaks into the ground or is slowly released into drainage systems. This reduces peak runoff , the sudden surge of water that overwhelms drainage and causes flash flooding. It's most effective for managing small-to-moderate storms and is increasingly required in new commercial development in flood-prone US cities.

What is the difference between a levee and a retention pond for flood control?

A levee is a barrier that keeps floodwater away from a protected area by blocking it. A retention pond temporarily stores excess stormwater and releases it slowly after peak flow passes. Levees protect against river flooding; retention ponds primarily manage stormwater runoff. Retention ponds are lower-risk if they fail because they drain gradually; levee failures are sudden and often catastrophic. Most flood-resilient urban systems use both.

How does hands-on engineering design help students learn about flood mitigation?

Flood mitigation is fundamentally about understanding water movement through landscapes , something that is genuinely difficult to grasp from text or diagrams alone. Physical models let students see how water flows, pools, and infiltrates in response to design choices. The iterative design cycle also teaches a key engineering habit: failure is data, not defeat. Students who redesign based on observed failure understand the engineering process at a deeper level than those who read about it.