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Watershed

Tara Cumming

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The Effects of Clear-Cut Logging on a Watershed

Watershed: the larger system made up of streams, lakes, rivers, and other bodies of water:

1. Watersheds are determined by the contours of the landscape, the vegetation covering the land, soil and rock formations, and prevailing patterns of climate in a region
2. It is important to realize how we affect water as it passes by us. Everything we do affects the plants and animals using the water downstream. People who get their drinking water directly from streams and rivers, are acutely aware of upstream activities such as: cattle watering and defecating in the water course, or towns discharging effluent.

Activity: Exploring the Workings of a Watershed Materials (to build the model watershed):

1. large tray (plastic, cardboard, or wooden) cardboard rolls, boxes, scraps, etc. glue gun, tape, scissors
2. scraps of green fabric large sheet of plastic
3. 1 cm x 2cm x 2cm chunks of green florist's foam (to resemble treed forests) watering can (to produce rain)
4. 3L water
5. towels to mop up any spills

A home-built watershed.

 

Procedure:

1. Build a watershed in the large tray or cardboard box
   - begin with mountainous regions at one end, working towards flat plains near the bottom
   - form a river or stream down the centre, with a lake or pond at the bottom
   1. use cardboard to build mountains and other terrain
   2. cover the entire works with the green fabric, then the sheet of plastic
   3. after dipping straight pins in melted glue, pierce plastic to stick pins in
      -these pins will be used to hold the 'trees'
      -place pins on upper mountainous regions
   4. place chunks of florists' foam onto straight pins, to resemble trees

    

2. Go through the following scenerios one by one, monitoring the water quality and volume at the bottom of the watershed after each.
   1. The mountains are covered with trees, when there is a great downpour.
      
      **Place a tree on each pin, and shower the mountains with I L of water. **
      
      What do you think will happen? Observe.
      
      Record the level of water in the pond: ____ mm
      
   2. A private logger selectively logs one of the mountains. There is a great downpour.

      **Remove saturated trees, and replace with half as many new ones. Shower with I L of water. **
      
      What do you think will happen? Observe.
      
      Record the level of water in the pond: mm
      

   3. c) Macmillan Bloedel gains ownership of the mountains, and clear- cuts all of them. There is a great downpour.
      
      **Remove all saturated trees, but do not replace any. Shower the mountains with IL of water. **
      
      What do you think happens now? Observe. -
      
      Record the level of water in the pond: mm
      ~
      

   Conclusion:

   -Everything that happens in a watershed will eventually effect the workings of the watershed downstream. We must be careful with our watersheds, in order to ensure a safe living environment downstream.