6. Tour of the CBW Courtesy of NASA/Goddard Space Flight Center Scientific Visualization Studio
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Hinweis der Redaktion
Procedure: Introduce program. Move through the slides asking questions to draw the answers out of the students. This section is to meant to be done fairly quickly to get all the students on the same page for basic knowledge that they can apply to watershed studies.
Discussion: Natural Resources occur in nature What are examples of things made by humans? What are some examples of NATURAL things? Are essential or useful to humans – this leads right into the next slide, so ask the students for examples
components of the water cycle Condensation Evaporation Precipitation Transpiration Point out the 3 states of matter.
Discussion: The Chesapeake Bay Watershed (CBW) has its headwaters (beginnings) in western New York, and covers parts of Pennsylvania, Maryland, Delaware, West Virginia, Virginia, and the District of Columbia.
Discussion: The CBW is 64,000 miles in area, so all of the people, plants, and animals living in or near this watershed feel the effects of all the types of human impact on the watershed (urban development, toxic dumping, deforestation, pesticide use, etc.) The Chesapeake Bay hold 27 trillion (that’s 27 and 12 zeroes!) gallons of water. That sounds like a lot of water, but remember that the whole watershed is only 1/5 the size of the Mississippi River watershed. Since there is less water to filter pollutants, we have to be even MORE careful about keeping the rivers and tributaries clean and reducing the impact humans have. The health of the Bay, the aquatic life, and our water supply depends on it. Historically, (colonial times) the CBW was about 90% forest. Remember how important trees are to reducing pollutants in the water and air. Today, the CBW is only about 58% (just over half) forest. The more trees we take down to construct buildings, the fewer pollutants we remove. What we build in place of the trees also adds pollutants to the water and air.
Procedure: Show the 5 2-liter bottles – they represent the water in the ocean. The beaker with 260 mL of water represents all the water not in the oceans. Pour half the water from the beaker into an empty cylinder. This represents the ground water on the Earth. Pour approximately 1/3 of this back into the first graduated cylinder. The remaining amount represents the fresh ground water in the Earth. Discussion: If a person drinks too much salt water, they will die of dehydration. The salt keeps the water from reaching the places in the body necessary for the body to function properly. So the oceans are not a good source of drinking water. There are certainly not a lot of glaciers near Virginia now (though they were in the past ice ages). Even if there were nearby glaciers, mining liquid water from a glacier is difficult and time consuming, making it not a good choice for feeding the ~300 million people in the USA. Ground water is the primary source of fresh water consumed by people. Only 1.7% of all the water on the planet is fresh ground water, so it is a precious natural resource . Procedure: Dip the dry sponge into the pitcher or paint tray so it absorbs a little water and starts to swell at the bottom. Discussion: You can’t see the individual water drops but you know they are held in the spaces in the sponge. You can squeeze the water out to use it. The sponge represents the aquifer, or the area of rocks that hold the water in the ground.
Procedure: Ask students to identify all the natural resources they see in the picture. Ask the students to think about their school yard. Identify the natural resources there. Discussion: This could be any river in the CBW. Water connects all the natural resources that we have (because there is so much of it all over the world).
Procedure: Point out the HRBT, MMBT, James River Bridge, etc. and the VASC to help students orient to this radar image. Ask students if they can tell where people have changed the landscape. What kinds of changes do people make? (Buildings, factories, harbors, clearing land for farms, pastures, etc.) Note: This is not a true color image, so you may want to also mention that the water is not really purple. Discussion: Paved surfaces block the recharge of the water into the ground, creating RUNOFF. Think of water running off the street during a storm – would you drink this? No! It’s full of oil from the street, bacteria from our waste, etc. All this water forced to other areas, creating flooding problems with dirty water. Growing crops and raising herds for food and other supplies uses a lot of pesticide and fertilizer. These chemicals get absorbed by water and can then contaminate the water table when it is absorbed into the ground. Factories, construction, and other industrial processes create waste that is toxic to humans. Historically, one way to “get rid” of these waste products was to dump them in rivers, streams, etc. Now we know that this kills fish, plants, and wildlife in and around our watersheds and forests, polluting our water and air. Now it’s up to us to monitor our water supply and keep it from be polluted whenever possible.
Discussion: Scientists monitor the health of the CBW in many ways. The water, plants, and animals are tracked and studied for changes. Dissolved oxygen is amount of oxygen in the water available to fish and plants for breathing. pH tells how acidic or basic the water is. Most plants and animals have a small range of acidity that they can live in. Toxic substances in the water can change the pH and kill plants, animals, and people. Too many nutrients = too much algae growth = blocking the sunlight = dying bay grasses which other aquatic life uses for food. Toxic substances kill the aquatic life. Turbidity is a measure of how much sediment is suspended in the water. Muddy water blocks sunlight to aquatic plants. Too much or too little bacteria make people, plants and animals sick. Days that the beaches are closed are usually due to too much bacteria in the water. This often happens after there has been a lot of runoff after a storm.
Discussion: We must reduce the pollution Contribute less pollutants to runoff, recharge Slow urban development in the watershed Clean up polluted areas – remove toxins Stop overuse of aquifer – conserve water! RECYCLE! – this is something everyone can do! We must increase the removal of pollutants Planting trees helps to filter pollutants Slowing development in forested areas Use environmentally-friendly construction Support cleanup projects
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