Defining a Watershed: Geographic Features

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1 What Is a Watershed? Key to the Sea Connection The concept of watersheds is the foundation of the entire Key to the Sea program. Ocean pollution problems and solutions start within our watersheds. Focus f If I say the word watershed, what do you picture? A shed or a little building with water inside? Something else? f Do you think you re part of a watershed? Background No matter where you live, you live in a watershed. A watershed is the area of land that sheds or drains water into a given river, river system, or larger body of water. It is the area of land from which water and pollution drain through a series of channels into a common outlet. In LA County, all watersheds drain to the ocean. 4. Infiltration or Runoff. Infiltration means water soaks into the ground. Runoff is when water flows from high points to low points, due to gravity. Defining a Watershed: Geographic Features Watersheds include areas of land that have mountains, creeks, streams, rivers, cities, streets, paved areas like parking lots and channelized rivers, and many other geographic features. The geographic features that define watershed boundaries include mountains, hills, slopes, headwaters and valleys. Water that falls on one side of a boundary flows downward with gravity into one watershed, whereas water that falls on the other side of the boundary flows downward with gravity to an entirely different watershed. Watersheds include natural and unnatural features. Natural watersheds have mostly natural features, such as mountains, trees, shrubs, grasses, dirt, and free-flowing streams and rivers. Water Cycle & Watersheds In order to better understand watersheds, let s review the water cycle. Water on earth is all connected in the water cycle. The SAME water has been cycling the planet since the beginning of time. The water cycle follows these steps: 1. Evaporation happens when heat is added to water molecules and causes them to slowly transform from liquid into vapor. 2. Condensation occurs as water vapor rises in the air with cooler temperatures and begins to transform back into its liquid state, forming clouds. 3. Precipitation occurs when clouds get heavy and water molecules collide, causing them to fall out of the sky as rain, sleet, snow, or hail. When water falls on the ground, it has two options: infiltration or runoff. 1 On the other hand, urban watersheds have unnatural features created by people. For example, parking lots, city streets, schools, buildings, and channelized rivers are part of the urban watershed. In most of LA County, urbanized watersheds dominate the landscape.

2 L.A. County Watersheds In Los Angeles County, we have five main watersheds: 1. Santa Monica Bay Watershed is bounded by the Santa Monica Mountains to the north, the Ventura-LA County line to the northwest, Griffith Park to the east, and Palos Verdes to the south. Water and pollution from within this large land area drain to the Santa Monica Bay. Within the Santa Monica Bay Watershed, there are many subwatersheds, or smaller drainage systems, which flow to the same body of water. One example is the Malibu Creek Watershed. 2. Ballona Creek Watershed drains parts of Sherman Oaks, West Hollywood, Beverly Hills, and Culver City. Water and pollution from within this area ends up in the Santa Monica Bay. 3. Los Angeles River Watershed extends from the eastern side of the Santa Monica Mountains and Van Nuys in the west to Pasadena in the east, San Gabriel Mountains to the north and Long Beach in the south, where its water finally empties into San Pedro Bay. One example of an LA River subwatershed is the Compton Creek watershed, which is mostly a concrete-lined channel. 4. Dominguez Channel Watershed drains water from portions of Hawthorne, Lawndale, Torrance, Carson, and Lomita, into San Pedro Bay. 5. San Gabriel River Watershed drains water from the San Gabriel Mountains, Pomona, Baldwin Park, and West Covina into the San Pedro Bay. The drainage path follows the 605 highway, down to San Pedro Bay. Vocabulary Bay body of water with land on three sides Channelized cemented over, refers to a pathway of water that is concreted over with steep channel walls versus a pathway of water that is natural and free-flowing Condensation transformation of water molecules from vapor to liquid Evaporation transformation of water molecules from liquid to vapor Geographic Features physical components of the environment which includes landforms such as hills, slopes, mountains, and valleys Headwaters the beginning of a stream or river Infiltration when water soaks into the ground Natural Watershed watershed comprised of natural features Precipitation rain, sleet, snow, or hail Runoff when water drains off the ground Subwatershed smaller drainage system that empties into a particular body of water Urban Watershed watershed comprised of unnatural features Water Cycle cycle that describes how water goes through the process of evaporation, condensation, precipitation, infiltration, and runoff Watershed area of land that drains water into a particular river, river system, or body of water Polluting our Watersheds Human actions influence watersheds. For example, urban development can threaten the water quality in Santa Monica Bay and San Pedro Bay. Channelized rivers were originally designed for flood control in the 1930s. Since many natural watersheds have been paved and channelized, including stretches of Ballona Creek and Compton Creek, water and pollution flows more quickly to the bay. Ground surfaces, urban runoff, the storm drain system, and ocean pollution will be examined in future lessons. It all starts with your watershed. No matter where you live, it all drains from your watershed to the ocean! 2

3 Activity: What Is a Watershed? Objectives Students will be able to: Define a watershed Describe the geography of local watersheds (such as mountains, rivers, and paved streets) Locate on a map and/or describe the watershed in which they live Name the final destination to which all watersheds drain in our area (ocean) Materials Wax Paper Spray bottle with water Watershed worksheet Colored pencils Procedure ACCESS PRIOR KNOWLEDGE 1. Review the water cycle, in order to set the stage for understanding watersheds. 2. Draw a diagram on the whiteboard of the water cycle, including the steps: evaporation, condensation, and precipitation. 3. Have students call out key terms (evaporation, condensation, precipitation) as you point and discuss each step of the water cycle. INTRODUCE NEW CONCEPT: Watershed 1. Write the word watershed on the board. 2. Break it down into two separate words. Draw a vertical line between water and shed. Connect this word with what students know about compound words. water shed 3 3. Tell students, We know what water is. Now ask students, What does shed mean? 4. Relate the verb shed to when animals lose their fur. Where does the fur end up? (On the ground). Guide student responses to come up with a definition of watersheds. 5. Define watershed as: the area of land that sheds or drains water into a larger body of water. Draw your own or show the Watershed worksheet/map. Geographic Features of Watersheds 6. Describe the geography of local watersheds. Note boundaries that separate watersheds such as mountains, slopes, and headwaters. 7. Tell students watersheds include not only geographical features we find in nature, like mountains and rivers, but also features made by people like streets and sidewalks. 8. Have students use whole body movement to show geographical features. For example, make a mountain peak with your hands, snap fingers to make sound of rivers, walk in place for city streets, etc. Demonstration: Wax Paper Watershed 9. Conduct a demonstration, to show how water flows in a watershed. a. Wad up and unfold wax paper, so that it has several creases and wrinkles. b. Arrange your wax paper on a desk. It should be 3-D. It should have high points and low points, creases symbolizing rivers, and other folds representing mountains, valleys, and geographic features. c. Use a spray bottle to spray water on it. What happens? (Water flows down and collects in the lowest points.) d. Have students come to the front of the class and spray water on the wax paper watershed. e. Make conclusions about the watershed (Water collects in low points, it runs off the wax paper, etc.)

4 GUIDED Activity: PRACTICE What Is a Watershed? UPPER (continu GRADES ed) 1. Pass out watershed worksheets to small groups or partners. 2. Describe the geographic features on your worksheet. Find cities, rivers, and the ocean. 3. Have students place their finger on a city or river. 4. Help students trace the path with their finger from: your city or river, to: a larger river and down to the ocean. While tracing the path, note larger rivers, highways, and other things on the map. 5. Prompt students, It all drains to the.... Have students shout out as a class, ocean! 6. Have students follow the directions on their worksheet to complete it. Evaluation/Assessment Ask students questions about watersheds. Here are some suggestions: How would you describe a watershed? What geographic features does a watershed include? (Mountains, rivers, streets) What separates one watershed from another? (Boundaries such as mountains) Have students make and describe their own wax paper watershed model. Have students complete their own worksheet as an independent activity. Grade Level Modifications To understand watersheds and the final destination to which water drains, use real-life examples. Here s one: If it rains in Pasadena, where does that water flow? Name the: 1- watershed in which the rain lands, 2- river that carries the rain from the watershed down to the ocean, and 3- bay in which the rain ends up. Fill in the blanks with other occurrences and other locations. Here s another example: If it snows in the San Gabriel Mountains, where does it flow? As a prelude to future lessons on storm drains and pollution, fill in the first blank with pollutants. Here s an example: If there s trash on the ground in Pasadena, where does that trash flow? Here s another example: If there s dog poop on the ground in Pasadena, where does that dog poop flow? Have students write a descriptive story of a water drops journey through the watershed. CA State Standards K E.S.3.a,3.b 2 P.S.1.e 3 L.S.3.c,3.d 5 E.S.3.b,3.c notes LOWER GRADES Spend more time reviewing the water cycle. Draw picture cards of land, clouds, and bodies of water to show each step. Use whole body movement for understanding features of a watershed through head, shoulders, knees, and toes. Head = Mountain tops, shoulders = streams, knees = rivers, and toes = ocean. Use the worksheet as an overhead. Draw a water drop. Have students verbally explain the path of the water drop through the watershed. 4

5 Where s my watershed? Name: Date: Use the watershed map to find the name of your city. If you can t find your city, use a freeway or a nearby city to help find your location. 2. Put a X with a marker or pencil on the location of your city and write it in the space below. My city is: 3. What watershed is your city in? Go to the legend and use that color to determine the name of your watershed. My watershed is: 4. Trace a line from your X to the nearest water way within your watershed. Draw an arrow along the water way down to see which bay your watershed drains into. My bay is: 4 5 LEGEND 2 1. Ballona Creek watershed 2. Dominguez Channel watershed 3. Los Angeles River watershed 4. San Gabriel River watershed 5. Santa Monica Bay watershed Watershed divide Freeway Waterway (river, creek, or channel)