Call yourself a Geographer ?

If so, can you tell  me what’s wrong with this answer taken from a question asked in the House of Lords via the excellent theyworkforyou website…

UK: Coastline

House of Lords

Written answers and statements, 23 June 2010

Lord Laird (Crossbench)

To ask Her Majesty’s Government what is the length of the United Kingdom coastline in miles at (a) low, and (b) high, tide; and what are the lengths of the coastlines of (a) England, (b) Northern Ireland, (c) Scotland, and (d) Wales.

Baroness Hanham (Parliamentary Under Secretary of State, Communities and Local Government; Conservative)

Information provided by Ordnance Survey for Great Britain and by Land and Property Services, an agency of the Department of Finance and Personnel for Northern Ireland, indicates that the lengths of the coastlines at mean high water (MHW) and mean low water (MLW), (mean high water springs [ordinary spring tides] and mean low water springs in Scotland) are:

Country Length of Coastline at Mean Low Water (MLW) [Miles] Length of Coastline at Mean High Water (MHW) [Miles]
England 8,417 9,462
Northern Ireland 620 542
Scotland 14,675 13,186
Wales 2,323 1,999
United Kingdom 26,035 25,189

These coastal lengths include all offshore islands, and land areas which are above MLW.

The precise length of coastlines will vary from time to time due to natural and gradual changes arising from coastal erosion and silt deposition.

Written and submitted from Warsaw Airport (52.177N, 20.974E)

24 replies on “Call yourself a Geographer ?”

I was trying to think if there were any coastal features in particular that give rise to this. For instance, is there anything at low tide which means that the perimeter (?) around it is less? If the low-tide-means-straight-lines is true, it should be true across NI, Wales and Scotland too. Given that the Thames and Severn are the largest estuaries, I wondered if it was to do with this and the prevalence of sand (which gives a straight coastline at low tide) vs. cliffs (which may give the same answer – if the sea always meets cliffs).

But in the end, I’ve calculated the ratios of each, and they’re roughly 1.12-1.14. Except for England, which is -1.12. So my guess is that it’s a typo.

The length of coastline is entirely dependent of the granularity of measurement, so varies depending on the size of your ruler. For every division by 2 of the length of measurement the coastline increases in proportion by a factor of two. Any locus is made of a number of datum points, the greater the frequency of datum points the greater number of measurements between them. As demonstrated by those fine chaps on BBC’s Coast.

Clearly it depends : Faversham Creek for example, at very low tide the sea water stretches only a few metres up the mouth of the creek, whereas at high tide the sea water goes inland a few miles. All depends what you consider the coastline the minimum and maximum intertidal zone? what saline measurement is used for brackish water? The answer is a lot more the closer you look and each section will have more or less coast depending on the height of the tide, it may actually be an impossible question to answer without a lot of caveats.

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