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What happens when rain hits the ground? Imagine a rainstorm in a wetland, such as the Delta. Grass, reeds, soil and vegetation act like a sponge, soaking up the water into the floor of the wetland. Imagine the same rainstorm on a road or an asphalt parking lot. These surfaces are solid and water has nowhere to go. As it flows along, it gains speed and is able to pick up and carry nutrients and chemicals that might be on the land. Soil not protected by vegetation is easily eroded or washed away by fast moving water. In this activity you will work in pairs to build a model of a wetland and test how wetlands act as a buffer and filter as they trap pollutants from city runoff flowing towards the estuary. Step I: Build your watershed and wetland 1. You will build a watershed with the supplies provided. Spread the modeling clay over half the pan. Leave half the pan empty to represent the bay or Delta. Shape the clay so that it slopes down to the bay. Smooth the clay along the sides of the pan to seal the edges. You can also form meandering rivers or creeks in the clay that lead into the bay. Be creative! 2. Next, create a wetland along the low edges of the land. To do this use the pieces of cut sponge or florist foam to completely fill the space across the pan along the edge of the clay. Make sure any gaps are filled in under and in between the sponges. 3. On top of the layers of sponge, lay down a layer of carpet to simulate wetland plants. Step II: Investigate the effects of rain on land with a wetland 1. Predict what will happen to the water when it rains. ____________________________________________ ____________________________________________ 2. Create rain on the land by spraying water on the upland area. 3. Record your observations: What happened to the water as it hits the wetland? ____________________________________________ ____________________________________________ Step III: Investigate the effects of rain on land with the wetland removed 1. Predict what will happen to the water when it rains on the upland. ____________________________________________ ____________________________________________ 2. Remove the sponge and carpet layer from your model and spray water in the upland area. Record your observations. |
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