Beach Profiles

Have you been out to measure a slope yet?  Maybe you’ve been to the beach but if not you can practice these fieldwork skills on any slope.

Here’s my results sheet.

Each measurement is the average slope angle for each 10 metre length.  (We are ignoring any changes in slope that happen between your two poles.)  So the first thing we can do is find an average for the entire slope.

How many measurements did you collect?  I’ve got 8.

Average is all of the measurements added together and divided by the number of measurements involved.

So I’ve got 2+5+3+3+7+10+12+4 = 46

and then 46÷8 (because there were 8 measurements).

So my average is 46÷8 = 5.75

Calculate the average with your results.

Now let’s try something a bit more complicated. We are going to draw the shape of the beach.  It’s called a beach profile.

You will need a sheet of graph paper or squared paper, a protractor, a ruler, a pencil and your results sheet.

Have your graph paper in landscape position and draw a line straight across near the bottom.  This is your base line.

You will need to choose a scale for your base line so that your measurements are evenly spread out but they all fit onto the paper.  Remember your poles were 10 metres apart each time.

 

Line up your protractor with the left hand end of the base line.  My first slope measurement was 2°.  I’ve used the scale on the protractor to mark 2° with a dot.  Do the same for your first measurement.

Now line up your ruler so that it is on the left hand end of the base line (where the centre of the protractor was just now) and also in line with the dot.

Draw a line from the base line towards the dot, but keep an eye on the lines that are printed on the paper and stop when you are at 10 metres on your scale.

You may not get to the dot or you may need to go beyond it, it depends on the scale that you have chosen and the size of your protractor.

This was the position of your second pole and the start of your second measurement.  Use your ruler to draw yourself a new base line.  The printed lines will help you to get it straight and parallel to the first base line. (It won’t go through your dot unless the first slope was actually flat!)

The centre of the protractor now goes at the start of this new line.  Make sure the zero line of the protractor is on the new base line and put a new dot for the second measurement.

Again use your ruler, from the start of the new base line, through the dot, to draw the slope and this time stop at 20 metres.

Have you got the idea?

Keep going until you’ve plotted all of your measurements.

Now you have a diagram which represents the shape of your beach – a beach profile.

Next week I’ll give you some ideas for further investigation.