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Washington State University

Floods – Engager: Skill Level Two


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ENGAGER – Skill Level: Two

Damage caused by heavy water flow


“Percolation Exploration” & “The 100 Year Flood”


Objective: Identify areas susceptible to flooding
Life Skill: Responsibility, Communication
Science Skills: Design a Chart, Collect and Interpret Data, Make Prediction

Preparation Activities:
Call your local County Public Works Department, DOE Storm water Specialists or a local meteorologist to find out about areas close to you that are known for flooding during heavy rains, and study the local map in “It’s All Connected”.

What You Will Need:

– Metal can (or other cylinder) with two open ends
– Pitcher or empty jug for pouring water
– Measuring cup
– Stop watch or watch with a second hand
– Pencil, Paper, Ruler or a software program for making a grid
– A flashlight might be helpful for peering into the can
– Access to the Internet

Activity: Percolation Exploration

A surface can be impervious (incapable of being penetrated) or permeable (open to penetration). When it rains, the ground can help by soaking up rainfall, or runoff is created. Run off that has little opportunity to soak in anywhere creates one of the conditions that can lead to flooding.

Have the youth read the following activity from beginning to end, and then have them design a data collection sheet to use for this experiment. The data they record will depend on the variables they choose to investigate. Once explored, they might also hypothesize and investigate other variables that affect permeability.


1) Find various land surfaces around your home or neighborhood such as grass, gravel, packed dirt, loose dirt, pavement, wood chips, a leaf pile, etc.
2) Put your cylinder on each surface that you’ve chosen. If you can, twist the cylinder into the surface a little.
3) Pour a measured amount of water, say 1/4 cup into the cylinder. Using your stop-watch, time how long it takes for the water to soak into the ground.
4) Using the same procedure, test the other ground surfaces you’ve chosen. Make sure to use the same amount of water and to record the time it took for the water to soak in to each surface.

Which surfaces soaked up water most quickly? Which soaked up the water most slowly? Did all of your surfaces soak up the water? Based on your observations, what do you think would happen in these areas during a small rainstorm? What about a big rainstorm? What other variables might affect how long it takes water to permeate a surface? How could we add those variables to our data sheet?

The “Hundred Year” Flood

Given what the youth have discovered about the movement of water and impervious surfaces, ask them to utilize the internet resources in Explore More and It’s All Connected to identify which areas in their neighborhood are more likely to become flooded.

What times of year does our area usually experience floods? What was the largest recorded flood you can find for our area? What does the term “100 Year Flood” mean?

Search the internet for information and images about large floods in your area. Weather forecasters and scientists usually classify large floods based on how often they occur.