Calculating Loss – Water Calculating Loss – Water RunoffRunoff

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What is your prior knowledge of What is your prior knowledge of groundwater?groundwater?

Turn to your shoulder partner and Turn to your shoulder partner and answer the following questions:answer the following questions:

1.1. Does your family have to haul water? Does your family have to haul water? If so, how often and how much at a If so, how often and how much at a time do you have to haul?time do you have to haul?

2.2. Do you know someone who hauls Do you know someone who hauls water? water?

3.3. Do you know where your water comes Do you know where your water comes from?from?

4.4. Have you ever run out of water?Have you ever run out of water? 22

Calculating RunoffCalculating Runoff

Think, Pair, ShareThink, Pair, Share•Where do we see water running off Where do we see water running off after a rainstorm?after a rainstorm?•How can we calculate how much How can we calculate how much water is lost due to runoff?water is lost due to runoff?

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Groundwater – What are we Groundwater – What are we doing to our planet?doing to our planet?

In order for groundwater to be replenished, precipitation must be absorbed by the ground. People, worldwide, realize there is a need for stable and adequate water supplies. Yet, in many countries, including the US, people are creating more urban areas. The development of our rural land into cities is one cause for a lack of a stable and adequate fresh water supply in the future.

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Why is this important to Why is this important to you?you?• Most of the water in the ground comes Most of the water in the ground comes

from precipitation that infiltrates from precipitation that infiltrates downward from the land surface.downward from the land surface.

• Large amounts of water are stored in Large amounts of water are stored in the ground.the ground.

• Today we will calculate the yearly Today we will calculate the yearly runoff created by a parking lot, and runoff created by a parking lot, and calculate the loss of water that would calculate the loss of water that would have entered the groundwater system.have entered the groundwater system.

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Explain to your face Explain to your face partner ..partner ..

• What is meant by groundwater?What is meant by groundwater?

• How does it get into the ground?How does it get into the ground?

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Calculating RunoffCalculating Runoff

• Square inches or cm are AREA Square inches or cm are AREA measurements, as is an acre. But, if square measurements, as is an acre. But, if square inches are multiplied by another inch (or inches are multiplied by another inch (or cm), the resulting unit is a cm), the resulting unit is a CUBICCUBIC inch, which inch, which is a unit of volume, just like gallons, liters, is a unit of volume, just like gallons, liters, etc. etc.

• This volume unit is what we need to find. This volume unit is what we need to find. Since cubic inches do not translate into Since cubic inches do not translate into gallons, we must convert inches to cm, cm gallons, we must convert inches to cm, cm to liters, then liters to gallons.to liters, then liters to gallons.

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Here are the conversion units Here are the conversion units you will need.you will need.

1) 1 inch = 2.54 cm1) 1 inch = 2.54 cm

2) 1 cubic inch = (2.54 cm)2) 1 cubic inch = (2.54 cm)33

3) 1 cm3) 1 cm33 = 1 ml = 1 ml

4) 1000 ml = 1 liter4) 1000 ml = 1 liter

5) 1 gallon = 3.8 liters5) 1 gallon = 3.8 liters

6) 1 foot = 12 inches6) 1 foot = 12 inches

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Conversion exampleConversion example

• 96 eggs = ?? Dozen96 eggs = ?? Dozen• we know that 12 eggs = 1 dozenwe know that 12 eggs = 1 dozen• 96 eggs 96 eggs x x 1 dozen1 dozen = the eggs unit cancel = the eggs unit cancel 1 12 eggs1 12 eggs• 96 96 1212• 96 dozen96 dozen = 8 dozen = 8 dozen 1212

Now we have successfully used a Now we have successfully used a conversion factor to go from one unit conversion factor to go from one unit to another!!to another!!

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ConvertingConverting

Step one: Step one: Convert inches of rain into Convert inches of rain into cm of raincm of rain

• _____________ (inches per year of rain) _____________ (inches per year of rain) x 2.54cm = ______________cm of rain x 2.54cm = ______________cm of rain per yearper year

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Step 2: Converting acres into cm2

•# acres x 43650 ft2 x (conversion #6)2 x (conversion #1)2 = # cm2

•_________ acres x 43650 ft2 /1acre x (12 inches/1ft)2 x (2.54 cm/1 inch)2 = ___________________ cm2

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Step 3: Finding the volume in centimeter and in milliliters

•Step 1 answer x Step 2 answer

•___________ cm x _________ cm2 = __________________________ cm3, which is the same as milliliters.

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Step 4: Converting cm3 to liters

•Step 3 answer x conversion 3 x conversion 4 = liters

•____________ cm3 x 1ml/cm3 x 1 liter/1000 ml = ________________________ liters

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Step 5: Converting liters to gallons

•Step 4 answer x conversion 5 = # gallons

•_______________ liters x 1 gallon/3.8 liters = _______________________ gallons

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..

Step 6: Finding the absorption amount

•Step 5 answer x percent absorption = # gallons lost to runoff

•________ gallons x 50% absorption = _______________________ gallons

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Pair upPair up

• For one minute share what For one minute share what surprised you most about how surprised you most about how rain runoff affects groundwater.rain runoff affects groundwater.

• Be prepared to share with the Be prepared to share with the class.class.

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HomeworkHomework•You will need to measure the base of

your house and any driveways, storage building, etc., that would keep water from soaking into your ground.

• Then you need to measure the total size of your lot. If you live in a multifamily dwelling (example: an apartment), approximate the size of the land in the complex that would be your yard.)

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Ticket Out the DoorTicket Out the Door

Write 3-5 sentences about…Write 3-5 sentences about…

•Why we should worry about runoff?Why we should worry about runoff?

•How we could design parking lots to How we could design parking lots to help solve the problem of water loss help solve the problem of water loss through runoff and help replenish our through runoff and help replenish our groundwater system?groundwater system?

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