Floods

®Vol. 24, No. 12

Dangerous WaterDanger – flood warning! Floods can harm

people, animals, buildings, and crops. Justeighteen inches of water can carry a caraway! Flood water can be only severalinches high, or reach the tops of houses. In the United States, about 130 people diein floods each year. Throughout the world,floods kill more people each year thanhurricanes (hur-ri-canes), volcanoes(vol-ca-noes), and lightning combined.

What Causes Floods?Floods happen when land that is

normally dry gets covered with water. Some of the worst floods occur when riversoverflow. This can happen after heavy rainor from quickly melting snow. Strong windsand heavy rain from hurricanes can raisethe sea level many meters, causing oceanfloods. Flash floods can develop quicklyafter heavy rain. The soil and plants can’tabsorb all the water from the storm. Flashfloods can be especially dangerous becausethey happen with little warning. Even a smallstream or creek can flood and suddenlybecome deadly.

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Protecting Against FloodsDams and levees (le-vees) can help

stop rivers from flooding. Sea walls canprotect people and buildings fromfloods in coastal (coast-al) areas. Somehouses are built on stilts to keep themdry in case of a flood. Sometimes, adam or levee can fail. During HurricaneKatrina in 2005, the sea level rosearound 25 feet. The levees thatsurrounded New Orleans broke, and thecity flooded. After two years, manyhomes and businesses ruined byflooding still have not been rebuilt.

Level C

houses on stilts

flash flood frommelting snow

broken levee

DID YOU KNOW??

Just 6 inches of

moving water can

knock a person down.

SCIENCE WEEKLY, Level C (ISSN 8756-1778), March 21, 2008 is published monthly in August, November, December, February, April and May; and, twice-monthly in September, October,January and March. Copyright © 2008 (Level C) CAM Publishing Group., Inc., 2141 Industrial Pkwy., Suite 202, Silver Spring, MD 20904-7824 U.S.A. (301) 680-8804 (800) 4-WEEKLY.Classroom subscription rate: (minimum 20 subscriptions to same address): $4.95 per student, per school year. Individual rate for orders less than 20 subscriptions: $19.95 per student,per year, payable in advance. Periodical postage paid at Silver Spring, Maryland and additional mailing of fices. Postmaster: Send address changes to Science Weekly, Level C,P.O. Box 70638, Chevy Chase, MD 20813-0638. Visit our web site at www.scienceweekly.com.C-2

Vocabulary

Weekly Lab

1 2 3

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5

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1. A structure built across a river to control floods

2. Houses are built on these to keep them dry during floods

3. Hurricane that hit New Orleans

4. Huge storms with strong winds that can cause floods

Another word for sea wall is: .

Step 1: Using the modeling clay, make a dam down the center of the meat loaf pan. Make it almost as high as the top of the pan.

Step 2: Fill one side of the pan with water. Did your dam keep the water on one side?

Step 3: Now press your thumb into the clay to make an indentation. What happened?

Step 4: Empty the pan. Make sandbags by filling the socks with sand.

Step 5: Wrap rubber bands around the socks as shown.Step 6: Stack the socks tightly around the sides of the

pan extending above the top of the pan.Step 7: Fill the pan with water. Now add some more.

How did your sandbags work?

clay, pan

sand

rubberbands

socks

water

water

Adult Supervision Recommended

Fill in the blanks. The letters in theyellow boxes will spell another word for sea wall.

How do dams and sandbags help people control water andprotect from floods? Build a dam and make some sandbags.

Use your science journal. Do you think the clay or the sandbags will workbetter? Which do you think will control water flow better? Write your

hypothesis.You need: a meat loaf pan, modeling clay, old children’s

socks, sand, rubber bands, water

DID YOU KNOW??Many bridges in placeswhere there are lots offloods have loud alarmsthat go off when a riveris about to flood.

Published by CAM Publishing Group, Inc., Silver Spring, MD • Publisher/Editor, DR. CLAUDE MAYBERRY, JR. •• Associate Editor, DR. LAURA GEHL • Writer, TRICIA ACTON • Artist, LINDA KING • Graphic Design and Production, LINDA KING • • Materials in this issue may not be reproduced in whole or in part in any form without special permission from the publisher.DISTINGUISHED

ACHIEVEMENTAWARD WINNER

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Writing in ScienceWhat supplies would you need to have if a flood were predicted whereyou live? What steps could you take to keep safe? Write a paragraphexplaining what you would do if a flood were coming.

MathThe strong winds and heavy rains of hurricanes often cause floods.Floods are expensive. After floods, homes, buildings, and roads mayneed repairing. Look at the circle graph below to answer the questions.

1. What was the total amount of damage from the hurricanes?

2. What was the amount of damage from thehurricanes other than Katrina?

3. What hurricane caused 7 times more damage than Dennis?

Now check the web site ofFederal Emergency Management at:http://www.fema.govto find their recommendations.

Dennis $2 billion Ivan $14 billion

Frances $9 billion

Katrina$125 billion

Rita$16

billion

Charley$15

billion

Wilma$16

billion

“What do a yo-yo, a swing, and a baseball bat have in common?”

“They are all pendulums!”“You will learn about pendulums in our next issue.”

ChallengeSome states have lots of flooding each year. Some states have less. It isexpensive to rebuild after floods damage cities and towns. Look at the map,below, then answer the following questions. You may need extra paper.

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Puzzle

1. Which states have the mostflood damage each year?

2. Which states have the leastflood damage?

3. Find your state on the map.Do you live in a state withlots of flooding?

Solve the rebus to find out something to do if a flood is coming.

$0.47 to $18.38

$197.8 to $682.3

$27.3 to$65.06

Average per Year spent on Flood Damage by State (Millions)Source: Center for Science and Technology Policy Research,

Data based on most current available$85.73 to $156.8

DID YOU KNOW??

Waves from a tsunami

can reach over 40

meters (131 feet) high.

DID YOU KNOW??The waves of a tsunami

can travel at 800kilometers (496 miles)

per hour.

Flood Costsin Millionsby State