Watersheds, Wetlands and the Watercycle


California Science Standards:
5th Grade, Earth Sciences (3a,b,c,d,e)
Water on Earth moves between the oceans and land through the processes of evaporation and condensation.

Objectives:

  1. Students will understand the parameters of a watershed by building a model and running water through it.
  2. Students will understand that the water cycle is a continuous path of water flowing down the land by gravity, and then returning to high elevations through evaporation, condensation and precipitation.
  3. Students will recognize the difference between point source and nonpoint source pollution by introducing red food coloring and cocoa power to the watershed model.

Introduction:
            Waterways like rivers, lakes, and streams are a vital expression of the water cycle in a watershed. The rain and snow that falls on the land seeps into the water table or travels across the surface to the sea. Some water evaporates or finds its way into plants and transpires back into the atmosphere to form clouds and precipitation again.
           With this picture of the water cycle and the rarity of this vital resource, it is important that communities recognize the path of water across the surface of the land as well as under it.
Watercycle Image
           A watershed is an area that is drained by rivers and streams and includes geographical structures like mountains, valleys, and man-made structures like buildings, parking lots and highways, and it also includes a rich biodiversity that is supported by the ecosystems within. As water travels through the watershed many types of pollutants may be carried downstream to places where wildlife thrives.
           Land-based marine pollution can either be from a “point source” or a “nonpoint source.” Point source pollution originates from a specific place such as an oil refinery or a paper mill. Nonpoint source pollution, on the other hand, is contaminated runoff originating from an indefinite or undefined place, often a variety of places (e.g., farms, city streets and parking lots, yards and landscaping, construction sites, and logging operations). The soot, dust, oil, animal wastes, litter, sand, salt, pesticides and other chemicals that constitute nonpoint source pollution often come from everyday activities. They are washed from lawns and streets into storm drains that often lead directly to nearby bodies of water such as streams, rivers and oceans. Pollution from contaminated runoff can affect aquatic ecosystems and cause the ocean to be unsafe for swimming or fishing.

Materials: Procedure:
  1. Assign students to groups of 3-4 students, discuss background information, and distribute materials.
  2. Allow students 20 minutes to build their watershed.
    1. Lay down paper towels on one end of the pan to represent wetlands.
    2. Use crumpled newspaper or cardboard to represent mountains.
    3. a.Place sand in the middle of the pan to represent urban and rural landscape.
    Model of Watercycle Image
  3. THE FIRST RAINFALL (before human development)
    Using the spray bottle, soak the crumpled paper on the top of the watershed.
    Let the water flow downhill and choose it’s own path through the sand to form rivers and streams. Describe the path of water through the model as it relates to elevation.
  4. Build a neighborhood using pennies, and a factory using one plastic bottle cap. Use pieces of wax paper to represent parking lots.
  5. Place a drop of red food coloring on each penny to represent non-point source pollution coming from individual homes, and a small pile of cocoa powder or ice tea mix on top of the bottle cap to represent point source pollution directly from a factory or landfill.
  6. THE SECOND RAINFALL (after human development)
    Using the spray bottle, soak the model. Let the water flow off the urban landscape and into the river, marsh and ocean. Describe the path of pollution through the model.
Questions:
  1. Where does a watershed begin and end? Does the water cycle begin or end?
  2. Using a map of your neighborhood, trace the path of water from the top of your watershed to the bottom. What are sources of pollution along the way?
  3. Why is non-point source pollution more difficult to control than point source pollution?
  4. If you were the mayor of the community in your watershed model, what would you do to stop pollution?
Condensation in Watercycle Image

Be Hydro-Logical


FACT: More water is used in the bathroom than any other place in the home.
ACTION: Turn off the water when you brush your teeth. Install low-flow toilets, shower heads and faucet aerators and you’ll save thousands of gallons/liters of water a year. It’s a savings that should reduce your water bill.

FACT: Today there are more people using the same amount of water we had 100 years ago.
ACTION: Don’t waste water. Use it wisely and cut back wherever you can.

FACT: A dripping faucet can waste up to 2,000 gallons of water a year. A leaky toilet can waste as much as 200 gallons of water a day.
ACTION: Check your plumbing and repair any leaks as soon as possible.

FACT: What’s dumped on the ground, poured down the drain, or tossed in the trash can pollute the sources of our drinking water.
ACTION: Take used motor oil and other automotive fluids to an automotive service center that recycles them. Take leftover paint, solvents, and toxic household products to special collection centers.

FACT: On average, 50% - 70% of household water is used outdoors for watering lawns, gardens and washing cars.
ACTION: Make the most of the water you use outdoors by never watering at the hottest times of the day or when it’s windy. Turnoff your sprinklers when it’s raining. Plant low-water use grasses and shrubs to reduce your lawn watering by 20% - 50%.

FACT: Lawn and garden pesticides and fertilizers can pollute the water.
ACTION: Reduce your use of pesticides and fertilizers and look for safer alternatives to control weeds and bugs.



Learn more by visiting www.epa.gov/safewater/kids/behyrdological.html