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 Difficulty Time Required Very Short (≤ 1 day) Prerequisites None Material Availability Readily available Cost Low ($20 -$50) Safety Adult supervision recommended for cutting materials that can create sharp edges, like plastic cups.

## Abstract

This project is inspired by the Banaue Rice Terraces, 2,000 year old structures carved into mountainsides in the Philippines. See if you can recreate the water flow of this ancient marvel, often called the Eighth Wonder of the World, using just household materials! The 2017 Fluor Engineering Challenge is over but you can still try out the project and compare your design to the high scores, or use the idea for a science fair or classroom activity.

## Objective

Build a model of a terraced irrigation system that uses flowing water to transport plastic beads. Beads start in the top layer and must flow through each lower layer until they are retained in the bottom layer.

## Credits

Ben Finio, PhD, Science Buddies

This project is based on the "Phil It Up" friendly competition designed by employees of Fluor Corporation located in Manila, Philippines.

General citation information is provided here. Be sure to check the formatting, including capitalization, for the method you are using and update your citation, as needed.

### MLA Style

Finio, Ben. "Follow the Flow." Science Buddies, 9 May 2018, https://www.sciencebuddies.org/science-fair-projects/project-ideas/CE_p025/civil-engineering/water-flow-system?class=AQUB9GhqIpSmA7cnenfKWfuCPH8GaofOLE-UMGbsOQE1Gz31lPOdrB4khN2W3cwuPgjbpvzfvsCtMT-DcTnGUqJiw6v0FreiOtn_w_OuvRU_hE5SXCInoyLzzsxPguFhIeE. Accessed 25 May 2019.

### APA Style

Last edit date: 2018-05-09

## Introduction

The Banaue Rice Terraces (Figure 1) are flat layers carved into the sides of mountains in the Philippines, which allow farmers to grow rice on the otherwise impossibly steep mountainsides. Amazingly, these structures are 2,000 years old—meaning they were made entirely by hand and without modern construction equipment!

Figure 1. One view of the Banaue Rice Terraces, an ancient engineering marvel in the Philippines.

The terraces were watered by an irrigation (the artificial application of water to plants for agriculture purposes) system that channeled water from mountain springs and streams down through the layers. This means the irrigation systems were powered entirely by gravity (the force that pulls things down towards the earth) as the water flowed down the mountainside.

In this project, your goal is to build a model of the Banaue Rice Terraces using some common household materials (Figure 2). You will design your terrace structure so plastic or wooden beads will be carried down from the top layer by running water, simulating the irrigation system in the real rice terraces. The beads are buoyant, meaning they float in water, because their density (mass per unit volume) is lower than the density of water. They get dragged along because water is viscous, meaning it exerts friction (a force that resists motion) when it flows past or around an object.

Figure 2. An example model of the Banaue Rice Terraces.

Designs entered in the 2017 Fluor Engineering Challenge had to be built using a limited list of materials and follow a specific set of rules. Move on to the Materials section to see the materials that are allowed if you want to compare your design to those in the contest. The rules are outlined in the Procedure. If you are just doing the activity for fun or for a science fair, you can choose your own materials.

## Terms and Concepts

• Irrigation
• Gravity
• Buoyant
• Density
• Viscous
• Friction

### Questions

• What purpose did the Banaue Rice Terraces serve?
• How were they irrigated without the use of electricity or modern equipmet?
• What determines if an object will float in water?

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## Materials and Equipment

• Designs entered in the 2017 Fluor Engineering Challenge (now closed) were limited to the following list of materials. Maximum allowable quantities are in parentheses. Scoring is explained in detail in the Procedure. If you want to compare your design to the high scores from the challenge, follow the same rules and scoring. Otherwise, use your own materials.
• Large (approx. 18 oz) paper or plastic cups (10)
• Small (approx. 9 oz) paper or plastic cups (20)
• Aluminum foil; cut a larger roll into pieces no larger than 10.75 by 12 inch sheets (27.3 cm by 30.5 cm) or buy pre-cut sheets from Amazon.com
• Popsicle sticks (50)
• Scotch® tape (1 roll)
• To test your machine, you will also need:
• Approx. 12 mm or 1/2 inch diameter wooden or plastic beads (10), available from Amazon.com or a craft store. The beads can have holes in them. Do not use glass marbles or metal bearings; they will sink!
• 1 liter (or 32 oz) plastic water bottle
• Tap water
• Metric ruler
• Large, shallow plastic tub to catch water if you are doing the project indoors, or an outdoor area where it is OK to spill water.

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## Remember Your Display Board Supplies

 Poster Making Kit ArtSkills Trifold with Header Poster Lights

## Experimental Procedure

### Overview

The objective of the 2017 Fluor Engineering Challenge was to build a gravity-powered irrigation system modeled after the Banaue Rice Terraces in the Philippines. While the contest is over, you can still follow this procedure for a fun science fair project or classroom activity. Watch this video for a complete overview of the 2017 challenge:

This project is a modified version of the annual "Friendly Competition" held between Fluor employees, which has stricter rules. The following slideshow shows some designs from the Fluor employee competition. You can use some of these pictures to get some ideas for your design, but note that the official Fluor competition had a different materials list than the student version of this project.

### Rules

Entries in the 2017 Fluor Engineering Challenge had to follow these rules. Entries that did not follow the rules were disqualified from winning prizes. You can follow the same rules if you want to compare your design to the high scores from the challenge.

1. Your model can only be built from items listed in the Materials section. No other materials are allowed.
2. There are no restrictions on the shape of your layers, and layers do not have to be the same shape. However, each layer must hold at least 1 cm of water at its deepest point (see Figure 3).
3. Your model must have a minimum of 2 and a maximum of 10 layers.
4. The bottom of each layer must be higher than the top of the next layer down (see Figure 3).
5. All ten beads must start from rest in the top layer, with no water already in the model.
6. You can only pour water into the topmost layer. There are no limits to how quickly or slowly you pour the water.
7. You cannot touch the model or any of the beads during operation. However, there is no limit to the number of attempts you can use to try and get a high score. If your model breaks or does not behave as expected, you can reset it (pour out all the water and put the 10 beads back in the top layer) and start again.

Figure 3. Side view of an example terrace structure.

### Scoring

Your total score is calculated using the equation:
• Bead points: each bead is worth 100 points per layer that it moves down. See Figure 4.
• For example, a bead that moves from layer 0 to layer 2 (counting from the top, so the uppermost layer is layer 0) is worth 200 points because it moved two layers. This means that the more layers your structure has, the more points you can get.
• Beads that fall out of the model are not worth any points; even beads that roll out of the last layer.

Figure 4. Layer numbering and bead scoring.
• Materials points: each item in the materials list has a "point cost" assigned to it, summarized in Table 1. Since more points are awarded when beads move down more layers, this means there is a trade-off: building a taller structure with more layers can earn you more bead points, but will require more materials. Note:
• Only materials used in your final design count towards your score. Materials used during the testing and prototyping phase do not count.
• Point costs are not pro-rated. If you use any tape, you are charged the entire 100 points. If you cut a popsicle stick in half and only use half of it, it still costs 10 points. Each 10.75 by 12 piece of aluminum foil counts as one full sheet, even if you do not use the entire sheet.
Item Maximum Quantity Point Cost (each)
Large plastic or paper cup (approx. 18 oz) 10 100
Small plastic or paper cup (approx 9 oz) 20 50
Aluminum foil, 10.75 by 12 inch (max) sheets 20 50
Popsicle sticks 50 10
Scotch® tape 1 roll100
Table 1. Materials and point costs.

To calculate your score, you can use the equation above, or use this paper scoring sheet or Excel score sheet to help you with the calculation.

### Testing Procedure

When building your model, you can test it and modify your design as many times as you would like. You can always re-test to try and get a higher score. There is no limit on the number of tests you can do, but you can only submit one score for the contest. When you are ready to do an official test to calculate your score, follow these steps:

1. Drain all the water from your model.
2. Place 10 plastic beads in the top layer of your model. Make sure they are not moving or rolling around at all before you continue.
3. Fill a 1 liter (or 32 oz) plastic bottle with water.
4. Pour the water into the top layer of your model.
1. There are no limits for how quickly or slowly you must pour the water.
2. You can only pour water into the top layer. Do not pour water into any of the other layers.
3. You do not have to use all of the water, but you cannot refill the bottle.
5. Wait until water has stopped flowing and all of the beads have stopped moving.
6. Calculate your score using the "Scoring" section.

### Tips for the Engineering Design Process

The Fluor Engineering Challenge is a good chance for students to learn about or practice the engineering design process. To use the engineering design process for this project, follow these steps:

1. Define the problem: What is the problem you are trying to solve, or what objective are you trying to meet with this project? (Hint: The objective is defined for you pretty clearly in the Overview section).
2. Do background research: Read the information in the Background section, check out the references in the the Bibliography, and do some additional research on your own.
3. Specify requirements: Are there any specific requirements your model must meet (Hint: See the "Rules" section)? Are there any additional requirements you want to define? For example, "the model should use a minimal amount of materials" or "the model should be sturdy and not fall apart when you pour water into it." Write down all the requirements you can think of for your model.
4. Brainstorm, evaluate, and choose a solution.
1. Brainstorm: Think of different possible designs for models that you could build. Make sketches of the different designs, and make a list of materials that will be required to build them. Try to come up with at least three different designs.
2. Evaluate: Compare your different designs. Which one do you think will satisfy your requirements the best? For example, does one model use fewer materials than the others? Does one look like it will be sturdier?
3. Choose a solution: Pick one design based on your evaluation.
5. Develop and prototype the solution: Build a prototype of your model, testing it out as you build. At this point, the engineering design process becomes iterative. That means you might need to go back to a previous step and start over from a certain point. For example, you might realize as you build your model that it is not sturdy enough, and you need to change your design. You might test your model by pouring just a little bit of water into it at a time, or placing the spheres in different starting locations to see where they flow easily and where they get stuck. It is okay if your model does not work perfectly on the first try. This happens all the time in real engineering.
6. Test the solution: When you think your model is ready, do an official test run by following the steps in the "Testing Procedure" section. Calculate your score using the the "Scoring" section.
7. Does the solution meet the requirements? Does your model follow all the rules of the contest? Does it meet any additional requirements that you set for yourself? How high is the score, and do you think you could do better? Continue brainstorming, prototyping, testing, and trying to improve your design until you are happy with your score.
8. Communicate results: If you are doing this project as part of a class or club, then in addition to submitting your score to Science Buddies, prepare a brief presentation or demonstration to show the rest of the class how your model works.

## If you like this project, you might enjoy exploring these related careers:

### Civil Engineers

If you turned on a faucet, used a bathroom, or visited a public space (like a road, a building, or a bridge) today, then you've used or visited a project that civil engineers helped to design and build. Civil engineers work to improve travel and commerce, provide people with safe drinking water and sanitation, and protect communities from earthquakes and floods. This important and ancient work is combined with a desire to make structures that are as beautiful and environmentally sound, as they are functional and cost-effective. Read more

### Environmental Engineer

Environmental engineers plan projects around their city or state—like municipal water systems, landfills, recycling centers, or sanitation facilities—that are essential to the health of the people who live there. Environmental engineers also work to minimize the impact of human developments, like new roads or dams, on environments and habitats, and they strive to improve the quality of our air, land, and water. Read more

### Sustainability Specialist

Are you passionate about the environment? Do you like developing and implementing new ideas? Do you enjoy talking with people about how humans impact nature? If these things are true about you, then you may be the ideal candidate for a job as a sustainability specialist. Sustainability specialists work in large and small corporations and universities to design and execute energy and resource conservation programs that reduce their employers' impact on the environment. This is a great career for people who enjoy working on teams, are socially responsible, and like to get things done! Read more

### Soil and Water Conservationist

Soil and water are two of Earth's most important natural resources. Earth would not be able to sustain life without nutritive soil to grow food and clean water to drink. Soil and water conservationists foster the science and art of natural resource conservation. The scientists work to discover, develop, implement, and constantly improve ways to use land that sustains its productive capacity, and enhances the environment at the same time. Soil and water conservationists are involved in improving conservation policy by bringing science and professional judgment to bear in shaping local, state, and federal policy. Read more

## Variations

Note: These variations are suggestions for students doing a regular science fair project. They are not eligible for the Fluor Challenge.
• Can you use your model to show how sediments are transported down the mountainside? What happens if you fill the top layer with dirt instead of using plastic beads? Can you see why erosion might be a problem for the rice terraces?

## Share your story with Science Buddies!

### Materials

Q: I cannot find 12 mm diameter wooden or plastic beads. Can I use something else?
A: The beads you use do not need to be exactly 12 mm in diameter, but should be as close as possible. However, other materials, like Styrofoam®, are not allowed because they may float better and provide an unfair advantage.
Q: Do I have to use red plastic cups?
A: No. Any large cups (paper or plastic) of any color are acceptable.
Q: I cannot find 10.75 by 12 inch aluminum foil sheets. What can I use instead?
A: If you do not have, or cannot find, precut aluminum sheets you can cut your own. The maximum size for each sheet is 10.75 by 12 inches (20.3 by 30.5 cm). There is no minimum size; smaller sheets can be substituted.
Q: Can we substitute any of the materials?
A: If you just want to do this project for fun or for a science fair, you can use whatever materials you want. In order to qualify for the 2017 Fluor Engineering Challenge, you must use only the materials listed in the Materials section.

### Scoring

Q: Is there a limit to how many tests I can do to calculate an official score for the 2017 Fluor Engineering Challenge?
A: No. You can re-test as many times as you want, but you can only submit one score per team.
Q: When scoring, what do I do if a bead falls out of the machine?
A: Beads that fall out of the machine do not count towards your score, even if they made it all the way to the bottom layer before they fell out.

The Ask an Expert Forum is intended to be a place where students can go to find answers to science questions that they have been unable to find using other resources. If you have specific questions about your science fair project or science fair, our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.