Wetlands Walk Adelaide Botanic Garden

Transcription

1 Wetlands Walk Adelaide Botanic Garden Student Activities Middle School Adelaide Botanic Garden Globally, just 1 in every 100 droplets of water is fit to drink. Most of the rest is salty or locked up in ice. In the 3D model alongside; The large ball of water represents all the water on the planet. The small one represents the fresh water on the planet. The dot is the fresh water that is available in rivers, lakes and dams for use. Water is a precious resource. The First Creek wetland in the Botanic Gardens shows how we might capture stormwater, use mainly plants to clean it and then store it underground for later use in the Garden. 1

2 Welcome to a working wetlands! Water and Air are our most valuable asset, not gold and diamonds. It is the essence of life on earth. Clean water is probably responsible for the improvement of health in society over the last 100 years as much as modern medicine. It cleans, refreshes our environment and plays a part in the beauty of nature. We need to value and protect it. South Australia is one of the driest places on earth and Adelaide is a growing city in that environment. The Water Cycle You are about to enter into a working wetlands to discover how it can act like a giant water cleaning and water storing machine. On your journey you will discover how plants are the beating heart of wetlands helping them to clean and conserve our scarce water supplies. Wetlands also add to the variety of life in our environment, provide valuable habitat for animals and insects and provide us with quiet places of natural beauty to enjoy. Use the map on the last page to locate the stations to visit. 2

3 Enter the Working Wetland Location: Bridge near National Wine Centre Water that enters this wetland starts in the Adelaide foothills, travels through Waterfall Gully and eastern suburbs then enters the Botanic Garden near where you are standing. (a) Where else might the water come from? (Hint look at the sides of the creek) (b) What problems might this pose for the wetland? Look upstream towards the Wine Centre walkway. (c) How do you know this is now an artificial waterway rather than a natural creek? (d) How do the changes to the natural creek affect the flow of water? (e) Sketch how the creek bed might have looked over 200 years ago before it Europeans arrived? 3

4 Look downstream near the bridge. Find the trash racks. (a) Explain how they work? (b) What material would get through? (c) Explain the benefits of trash racks, not just nearby but much further downstream? (d) Why were the trash racks positioned at this point in the Garden? (i) What has to be done regularly to them to keep them working properly? Look further downstream. (g) Is the creek more natural or artificial here? Why? (h) What do the big rocks do? (i) Is there a more natural looking way of doing this? 4

5 2. Location: Wetland water intake. On the vineyard side of the creek walk upstream and find where water is diverted from First Creek into the wetlands. DANGER: Keep away from the edge of the creek wall. (a) Explain how water gets diverted. (d) Why is there a cage here? (d) Is the shape of the cage important? Explain. (e) Suggest reasons why only some of the water from the creek is diverted into the wetlands? 3. Location: Gross pollutant or Sediment trap Water travels underground from First Creek to the gross pollutant trap buried under your feet. Look at the diagram on the steel plate that explains how it works. (a) Point in the directions of where the water enters and leaves the trap. Does all the class agree? (b) Explain in your own words to someone else how the trap works. (c) Is the trap designed to capture small or large particles before they reach the wetland? Explain. 5

6 4. Location Wetland - Settling pond Look over the railing at the first of THREE major ponds that make up the wetland. This is the settling pond. (a) Is the water still or fast flowing here? (b) How do the high banks help? (b) What happens to sediment after it has been in still water for a while? (c) Over time what problem might this cause in the pond? (d) Would the water be clean enough for safe use after leaving this pond? Why? 5. Location: Wetland Crossing - Filter pond On the trash rack side of the pond, walk next to the wetlands until you see to the rock crossing. DO NOT go across until directed to do so by your supervisors. Water flows from the settling pond to the filter pond. This crossing and another mounded bank further down divide the filter pond into three sections (a) List the differences you can see between the filter pond and the settling pond? (b) Count how many different types of plants can you see in the ponds? 6

7 (c) Do many of the plants have common features? If so what are they? (d) Most of the plants might be classified as: (circle one) Trees / herbs / bushes / reeds / vines 6. Location: Reeds Filter pond DANGER: If it is safe to do so walk carefully with your supervisors to the reed sculpture in the middle of the pond. You are now in the middle of the working heart of the wetland surrounded by mainly reed-like plants. (a) What problems might wetland plants face living here.) (b) Look closely at nearby reeds and soil. Why are the following features important for living in wetlands? Tall narrow stems. (c) Why are the flowers high up on the plants? (d) On the base of the plant, why do they have horizontal underground stems (rhizomes) and clumping roots? (e) As a class group look at the metal information sign closest to you to find which one of the following is the water cleaner. (Circle one.) An animal / an insect / bacteria / a plant (f) Reeds slow down / speed up the flow of water through wetlands. (Circle one) (g) How does slowing down the speed of water help clean the water? You are standing on one of two mounded rock banks which divide the filter pond into three sections. Finish crossing the wetland and walk up onto the lookout. 7

8 7. Wetlands Lookout Pumps and Storage From here you can see the filter pond divided up into 3 parts by the rock walls. Water is pumped from the deep end of the filter pond to be stored underground. (If you turn around you can see the large pumps behind the red three storey building.) The diagram on the lookout gives the best idea of how the water flows through the system. (a) Water taken from the filter pond goes through mechanical filtration including ultra violet like before it is pumped underground. Why do you think this is the case? 8. Plant ponds Water Loving Plants Walk down past the small trickling waterfall to the plant ponds. Water plants have many different features to help them survive in water of different quality. Stop and enjoy looking at and learning about just a small fraction of the world s water plants. Feature Plant Name Floating leaves Carnivorous Grey Rush Thrives in poor quality water Provides food Native to South Australia (a) Complete the following table using the signs on display. (b) Name one threat to our native water plants. 8

9 9. Web of Life Underwater viewing Walk down to the glass viewing panels next to the biodiversity panel. Did you know that there is more life in a healthy wetland than in almost any other habitat? Look for water creatures (macro-invertebrates) through the glass panel near the surface and in the water. (a) Draw one of the animals. (b) Can you find a match with any animals you see on the wall panel? YES / NO (circle one) (c) From observing the wetland and the wall panel, make up a wetland food chain on the diagram below. 10. Bridge - Storage pond The water in the storage pond is ready to be pumped to the garden to water the plants. (a) Where was water pumped from to get into the storage pond? (b) What are the benefits of only storing water here for a short period of time before using it on the Garden? (c) How might it be different to water coming directly from First Creek? (d) What are some of the benefits of using this recycled water? Water is so important to all life and has a special beauty that many people have written about it. Some ideas are inscribed on the metal circles on the bridge. 9

10 11. Rock sculpture Storing water underground in an aquifer On your way to the sculpture, stop at the pump-house and look at the different pumps that draw water from underground into the storage pond and then into the garden. (a) What are the advantages of pumping water from this wetland rather than from the River Murray onto the Garden? Walk over and stand in the middle of the rock sculpture. Imagine you have become a microscopic drop of water and you are 100 metres under the ground here, the blocks surrounding you are tiny sand grains! (b) Can you fit between the blocks? YES/NO (c) Can your class or group all fit between the sand grains (blocks)? YES / NO The rock sculpture is a model of an aquifer (or underground water storage), the spaces between sand grains or cracked rock fill up with water seeping from the ground above. (d) What are the advantages of storing water in an aquifer rather than tanks or reservoirs? (e) What might be any disadvantages? In the future it is expected that 100 megalitres of water per year will be pumped from the aquifer to water the Botanic Gardens. (e) Describe a space that is about 1 megalitre. 12. Floods good and bad Nearby find the creek depth flood marker. (a) Using the height marker for a 1 in 100 year flood, predict what surrounding areas would be worst affected. (b) What could be done to prevent this area flooding? (c) How can flooding be good for the natural environment? 10