Slope Measurement

It’s time to get out and do some fieldwork.  Fieldwork is all about investigating things: finding out for yourself.  You could just go and look, but if you take some measurements then you have proof to back up your conclusions.

We’re going to be learning some fieldwork techniques that can be used to investigate coastal environments, so you can look forward to some days at the beach.  But first you need to gather some equipment.

You will need:

  • 2 long garden canes
  • Some coloured tape
  • Protractor
  • A drinking straw
  • A piece of thin string with a weight tied on the end
  • A 10 metre length of string (or a tape measure)
  • Clipboard, paper and pen

The garden canes need to be turned into ranging poles.

To do this, stand them side by side and wrap a piece of coloured tape around each pole at the same height.  (Tip – do it at about the eye height of the smallest person who will be using them!)

The protractor, straw and weighted string need to be turned into a clinometer.

If your protractor has a hole at the point where all of the lines converge then that is where your string needs to be tied.  If there is no hole you will need to tape it into place.  The tape needs to hold the string so that the weight can pull it taught to line up with any of the lines on the protractor.  (Ignore my loose end)

 

Check it at both ends of the scale and reposition if necessary.

 

Finally tape the straw so that one of its edges is in line with the 90° on the protractor.

If you’ve got a 10 metre long tape measure, then great – use that.  If not, use a shorter tape measure or ruler, to measure a 10 metre length of string or rope.

Clipboard, paper, pen…that’s it.  Are you ready?  Find a slope and let’s have a practice.

You’ll need at least one helper but it is best to have two.

Start at the bottom of the slope and lay out your 10 metre string, rope or tape measure, going directly up the hill.

Give one of your poles to one of your helpers and ask them to stand and hold it in place at the uphill end of the 10 metres.  Make sure the pole is vertical and resting on the ground.

Take your other pole to the bottom end of the 10 metres and position it in the same way.

Now take your clinometer and hold it by your pole so that the straw is in line with the top of the coloured tape.

Look through the straw until you can see the top of the coloured tape on the pole up the hill.  Then freeze.

Keep your eye on the top pole, through the straw, while your other helper checks that the straw is still in the right place on the bottom pole and then makes a note of the angle by reading the scale on the protractor.

This one shows 10°

Tricky!  That’s why it’s worth practicing before you get to the beach.  We’ll talk more about that next week.