1 EAGLETON NOTES: How Long Is A Coastline?

.

.

Saturday, 20 April 2013

How Long Is A Coastline?

It's amazing what comes out of very simple thoughts.  I was embarking upon a post on A Hebridean in New Zealand with the statement that the coastline of New Zealand is [a number to be looked up] kilometres long.   When I came to look the figure up I discovered that it's not quite as simple as I thought.  The coastline of NZ varies in the Wikipedia article on List of countries by length of coastline from 9th place with a coastline 15,134 km long using one source to 17th place with a coastline 17,209 km long using another.  The first source was The World Factbook and the second The World Resources Institute.  If you happen to be interested in more detailed information then you can follow the links.  I've just spent a very interesting time doing just that.  It all boils down to the use of straight lines to measure the coastline and the length of those lines.  The shorter the line the more accurate the figure and the longer the coastline.

For those who play in pub quiz teams (here's one for you Meike) Canada has the longest coastline using either measurement.

How about this for an interesting (and totally useless) piece of information:  The country with the coastline to highest land mass ratio in the world is the Coral Sea Islands with a landmass >3 km², a coastline of 3,095 km and a land/coast ratio of  >1,000,000.  Next, wait for it, comes the Spratly Islands with a landmass >5 km², a coastline of 926 km and a land/coast ratio of  ≥200,000.

The where?  I have to confess never even having heard of the Spratly Islands.  It turns out that they are not a country as such and have no native inhabitants.  However about 45 of the islands are occupied by relatively small numbers of military forces from China, the Taiwan, Vietnam, the Philippines, and Malaysia.

Well didn't you just want to know all that?

10 comments:

  1. What does that say about me when I confess that I absolutely LOVE knowing such things?
    Graham, if the coastline-question ever comes up in a pub quiz and our team will be victorious because of this special knowledge, I'll send our prize (bottle of Tullamore Dew) to you!

    ReplyDelete
    Replies
    1. Well I may live in Scotland but I'm not so proud that I wouldn't accept an Irish Whisky! (I've a funny feeling I've made a grammatical booboo there somewhere.)

      Delete
  2. A simple way to think about this is to imagine drawing a circle using an increasing number of straight lines (which will get shorter the more you have) where each line has to start and end on the circle you are trying to approximate. The more lines you use the closer you get to a circle (a triangle clearly isn't very circle like), the larger the area, and the longer the circumference becomes. It's another of these weird things I happen to know because of computers (curves always consist of a set of square pixels, so you are always essentially drawing lots of straight lines -- although even drawing straight lines using small dots isn't entirely straightforward).

    ReplyDelete
    Replies
    1. Ta Mark, You summed things up very succinctly.....GB has also started delving into 3D modelling as well....He should get out more. Land mass be blowed. He'll be giving dissertations on mountains next. I can't understand folk who spend hours trying and in my case failing to make computers do things they shouldn't, in a simple world, be capable of.

      Delete
    2. Lines is simple Adrian. Well it is compared with PS6 and all the things you play with. Head-banging stuff I'd find it.

      Delete
  3. I'm not sure if I would use a straight line to measure a coastline...being a quasi-perfectionist, I'd probably be measuring every single inlet no matter how small, to get the measurement just right.
    Never heard of the Spratly Islands until now...now I know.

    ReplyDelete
    Replies
    1. I would have said that was easier said that done Virginia. However see CJ's comment below.

      Delete
  4. There is currently a survey going on in either Scotland or Britain as a whole (it was on the BBC programnme 'Coast') in which the coastline is being measured in three inch (again I'm not certain of the figure but I know it was that sort of figure)units. The surveyors were shown wandering along a peice of rocky coast at the tide line measuring with tiny rulers. (Don't ask me what they do about the bits no human can reach). The point was made there that the end result will show the coastline to be infinitely longer than the figures currentyl being used but that even then the figure would be notional because if you used a two inch rule instead it would be longer again...

    ReplyDelete
    Replies
    1. Thanks for that piece of information CJ. I'm surprised that it isn't being done by GPS. I've just thought of that as a possibility.

      Delete
  5. Oh PERLEEEEEESE! Nuff said.

    ReplyDelete